Category: repair

#0035: repair and analysis of a talon style folding lock knife

Otto

#0035: repair and analysis of a talon style folding lock knife

Preamble

I was recently given this folding lock knife to fix for someone. The internal mechanisms of which I found mildly interesting, so I figured it would be worth the time to document it. It may also prove useful for future reference incase I come across something similar.

Initial observations

The first thing that I noticed whilst examining this unit is the unusual blade shape. This is a talon type blade. It is a single edged, crescent shaped blade that curves forwards and terminates in a single point. It’s crescent shape, coupled with the blade edge being on the inner concave curve: give it both a visual as well as function resemblance to the talons of birds of prey. The blade is designed to roughly function in the same way: to pierce and then to hook. This shape of blade can easily convert slashing motions into pierces, due to the blade tip being the leading contact point.

The blade description above may lead you to think that the pictured example knife is a deadly weapon. And that would be the case, at least if not for my second immediate observation. Which is that this knife is a mass produced (I assume) chinese special tacticool toy knife.

It is rather cheaply made, and only really aesthetically resembles the weapon that it is aping. This pictured knife is just a box cutter. That is also it’s literal function currently. Its what the knife’s owner, who is a warehouse operative uses it for. It is also the only thing that it can be used for in my opinion.

Faults

The main thing that was wrong with this unit is that it was not maintained properly. The owner did not tighten the various torx screws on this thing as they worked themselves loose. This led to various joints and mechanisms developing too much play in them. This then resulted in the blade being seated at a crooked angle. Which in turn allowed the blade tip to scratch the handle as it was retracted into it.

Additionally due to the owner’s negligence: some of the various screws that loosened over time, fell out entirely and were consequently lost. This is rather unfortunate, because these fittings consisted of a paired torx screw and socket nut; that where sized to fit flush into the recesses of the handle plates. The socket nut especially is rather annoying to replace. Requiring a specific purchase as it is rather uncommon, and wouldn’t likely be present in any of my bins of miscellaneous salvaged hardware.

The blade itself also has an issue. The main one being that it is made from a miscellaneous soft junk metal; and the second one is that it was currently dull. So it required a basic sharpening, in order to make this knife operable. At least for the relatively short time period that the blade’s soft metal can maintain a serviceable edge.

Parts list

A complete version of this locking knife consists of several discrete components:

  • 1 x camouflage painted outer metal knife handle plate (left)
  • 1 x camouflage painted outer metal knife handle plate (right)
  • 1 x black painted metal inner frame with spring compartment insert gap
  • 1 x black painted metal inner frame with blade locking wedge
  • 1 x black painted metal finger guard with box cutter point
  • 1 x grey painted talon style blade
  • 1 x metal spring
  • 1 x metal spring compartment
  • 2 x plastic washers
  • 4 x smaller black painted metal hex screw and blind nut set
  • 1 x larger black painted metal hex screw and blind nut set
  • 1 x black painted metal trouser clip
  • 3 x black painted hex screws for the trouser clip

Tools and materials

Tools:

  • Round edge metal file
  • Knife sharpener rod
  • Torx screwdrivers (T7, T9)
  • Tweezers

Materials:

  • plumber’s grease (or equivalent)

Repair

There really isn’t much to say on the repair itself, as its pretty straight forward. I disassembled then reassembled the knife; fixing everything dodgy about it as I went.

Actions:

  • Completed knife disassembly.
  • Bent the blade locking wedge on the inner frame so that it stops the blade from folding closed more reliably.
  • Greased the blade’s damaged plastic washers to help prevent future wear.
  • Bent the blade spring’s hook into a right angle in order to get a better hold on the blade.
  • Re-greased the blade spring within the spring compartment due to presence of dry grease here.
  • Re-tightened all the screws and socket nuts that keep the housing together.
  • Added a stand-in replacement for a missing screw and socket nut pair that consists of two screws and a salvaged threaded brass insert nut.
  • Added a plastic screw and nut to help hold frame. I chose plastic so that I could cut down the screw and round off the nut easily so that it doesn’t snag the user’s hand.
  • Performed a basic sharpening on the blade using a metal file, then honed the edge using a knife sharpening rod.

The actual repair itself is hardly anything to be proud of. It wasn’t a hard repair and didn’t even take long. However this knife has been saved from going into the rubbish bin, for at least another couple of months, and that should be the main take home. This thing is ready for work again; and should stay that way for quite a while.

Before and After video demo

Before

After

Recommended modifications

1) Grinding the blade edge and sharpening.

The knife blade could use a proper grinding and sharpening: if it to be used for anything more involved than opening boxes. I recommend grinding the blade down so that the angle of the blade edge slopes smoothly up to the mid-ridge. That way the blade can have more acutely angled edge.

This will consequently make the blade sharper than it currently is. A smaller angle will also remain sharper for longer whilst in use, due to the relative thinness of the new blade edge. Even as it dulls. Although the blade will also likely become more brittle and likely to snap as a consequence of the severe loss of material this newly angled edge will require.

2) Installing a blade backstop.

A blade backstop will stop the blade from over-rotating when it is extended. It will also prevent the blade from wobbling when extended by sandwiching it between the backstop and the blade locking wedge.

This knife likely already had a blade backstop of sorts, as it already has the screw holes where on could be mounted. However it was probably lost during use. As it is the blade overextends backwards when it comes in contact with any material that resists it.

3) Thread locker on the screws.

Thread locker such as “Locktite 243” when applied to screws prevents them from slowly working themselves loose during operation, due to factors such as vibration. This will extend the lifespan of this knife when applied to the screws that hold the frames together, as it will mean that they will (largely) no longer need to be checked and re-tightened at intervals.

And since we have already established that this knife’s owner is averse to maintaining his equipment: the lower the level of maintenance this knife needs, will be proportional to the extension of it’s operational lifespan. I.e. it will last as long as it lasts, if the thread locker can keep it together for longer, than it will last a little longer as a consequence.

4) Installation of additional retaining bolts.

I think that installing a few additional bolts and nuts to keep the frame together would greatly increase the overall structural strength of this folding knife. As it would share the strain of keeping the unit together amongst more points. This would allow this knife to be used in applications that require more force.

Although one has to be careful not to drill and install any bolts within the blades seating area within the knife handle housing, or within it’s pathway. Common sense right?

Post mod roles

As it is this knife tool is weak and too dull for any real work beyond cutting the tape off of cardboard boxes. however I theorise that if the above mods are made, then one would end up with a stronger, sharper, and more stable tool.

This would then allow the tool to used in a broader array of applications. For example light wood working, or bush craft applications. A talon style blade is good in both of those applications. The sharp hooked point is good for carving detail into wood. The concave blade is good for gripping and working with rounded objects like natural woods (sticks and branches). For example: for sharpening sticks, or for feathering wood to create tinder. It is also good for harvesting (in this case smaller) plants; as the concave blade helps bundle the stems together when cutting. Like a miniature sickle.

I could go on but I hope you get the point. The issue here is not with the knife’s design, it is with it’s flawed construction. If that could be remedied (or at least alleviated), then this knife could actually become a useful tool. It just requires work to get there.

Closing thoughts

Honestly, I actually rather dislike these types of low-cost low-quality mass produced items. This knife for example: it’s low-cost promotes replacement rather than repair: as it can very quickly make many repairs in it’s owner’s eye deemed as uneconomical. And that is assuming that the owner has a mend-and-make-do mentality to begin with. Most contemporary consumers do not. They have a use and replace mentality.

The main reason why a person may want to repair these things in my mind: is either philosophical (i.e. environmental conscientiousness, fiscal responsibility, anti-consumerist sentiments, etcetera); emotional sentimentality (e.g. hand-me-down from a relative); or if they are in severe financial strife and literally can’t afford to replace a £3.99 work knife.

Now look at it’s cheap build and materials. This factor exacerbates the issue above. Chiefly because it lowers the tools operational lifespan. This is the time it is in use, before it somehow breaks on it’s owner. Hence sooner putting them in a position to make the call on whether or not to either repair or replace the tool.

I do consider a knife like this to have been built with planned obsolescence in mind. Even though the term is hardly used for mechanical hand tools like knives; as it is usually reserved for electronic or computer products.

However, consider this: if the user does no maintenance on this knife. Then there are only so many operational hours that it is capable of before completely falling apart, or at the very least becoming inoperable. It’s shoddy build quality purposefully limits this simple hand tools lifespan. And when it is over, the user is expected to then purchase another one. That is a form of planned obsolescence.

I hate preaching, but please consider not buying this kind of shite. There are better alternatives available. Such as buying second hand quality tools. I always advise that people do the requisite research first. Then spend what they can afford in order to get the best value tools that they can, for their specific use case.

I said “Best value”, not most expensive. A chrome-vanadium spanner is a chrome-vanadium spanner at any price. Just because a person pays more for a brand name, doesn’t necessarily mean that their chrome-vanadium spanner is better than the off brand one.

Nowadays, it’s rather likely that they were both made in the same factory from the same material stock. An idea that would be laughable, if it wasn’t also true. Many brands on the market don’t manufacture anything. They purchase orders from the same OEMs then label the products as their own.

*proceeds to mount high horse.

If you absolutely have to purchase at the bottom of the market because you absolutely have no more money to spend. Then spend time instead. Time upgrading, fortifying, and maintaining your tool. This is so that it can last as long as you need it to. Or at the very least extend the time intervals between new purchases.

That being said, it is an unfortunate reality that most people who do mindlessly purchase bottom of the market products like this knife: are either unable; or more commonly, unwilling to invest time in their tools. They are in many cases content to use the shoddy tool in the short time until it breaks. Then purchase another bottom of the market shoddy tool to replace it with. Repeating this loop of short-sighted wasteful false-economy ad infinitum.

*proceeds to dismount high horse.

I feel that I should somewhat qualify my rather negative sentiments against these types of bottom market products. In the past I have worked within a small recycling facility, one that primarily serviced my local community on behalf of the local council, as well as the surrounding areas. (The point is that we weren’t shipping it’s garbage in.) I worked there as a materials sorter.

It gave me a certain perspective on the sheer volume of material wastage people engaged in. For a supposedly poor community, the amount of waste of useful materials was astounding. Every night I came across hundreds (not hyperbole) of very useable tools of all kinds. Everything from: screwdrivers, knives, drill bits, and spanners, to pots, pans, skillets, as well as whole bicycles some nights. All of that thrown away for recycling.

Many of these things were in decent conditions. Conditions that required either basic maintenance such as: sharpening, some hammering, replacing a handle, or realigning, or even a simple old fashioned cleaning. Gasp! Working there made me dislike a lot of these products; as when I now see them new: I think of where they’ll likely end up in less than a years time … In the fucking trash.

I just don’t like companies purposefully making tools/products that have such a short lifespan designed into them. I doubly don’t like it when these same products are purchased, used, and then wastefully discarded, by people whom I have heard a thousand times: claim poverty. But that’s another rant entirely.

Thank you for listening. It really helps.

Term glossary

OEM – Original Equipment Manufacturer

#0034: Repair and analysis of a tap cartridge

Otto

#0034: Repair and analysis of a tap cartridge

Preamble

I recently had to repair a constantly dripping kitchen faucet, and thought that I may as well document it. Especially since I found the construction of the cartridges within the tap to be rather interesting. Although I must say that the title does make me feel a bit silly.

Tools and Materials used

Tools:

  • crescent wrench / 17mm wrench
  • nylon spudger / pry tool
  • phillips screwdriver
  • soft bristle toothbrush
  • plastic container
  • pipette
  • teaspoon

Materials:

  • petroleum jelly / plumber’s grease
  • vinegar
  • water

Tap cartridge inspection

I’d like to start by examining the water faucet’s cartridges themselves, as this information will be relevant later during the repair. The two pictured cartridges were taken from a quarter turn kitchen tap. This is a tap that only requires the handle to be turned 90 degrees around it’s axis, in order for it to go from a fully shut to a fully open state, and vice versa.

This type of cartridge is designed so that water flows into it from the central hole at it’s bottom inlet. This water then flows up inside it’s shaft, and through the two holes within the first ceramic disc. It is then diverted out through the two radial holes on it’s side via the second ceramic disc. At which point the water has a direct route to the faucet head.

This particular type of cartridge has two ceramic/plastic discs within it, that in conjunction with each other operate as a single water control valve. They do this by establishing a water tight seal between them; a press fit seal that is created by the two discs merely pressing against each other in a way that eliminates any gaps between them.

This seal is demonstrated within the video below, where you can see a suction effect take place between the two discs. This suction helps the two discs adhere to each other when wet. This is only possible due to the absolutely smooth surface of the first disc, coupled with the hollow cups present on the second disc’s contacting surface.

These two ceramic valve discs are both keyed to fit into their brass metal shaft in one particular orientation. This orientation has the bottom disc operate as a fixed or stationary valve. Whose job it is to split the ingressing water into two separate streams. It does this via the two distinct triangular quarter-circle holes within it. This lower disc is keyed to fit into the inner wall of the cartridge’s cylindrical housing in a way that makes it immovable.

Whereas the top disc is keyed into the rotating tap handle cylinder attachment. This allows the tap handle to control the rotation of the upper disc. This upper disc is cut in a way that either blocks the two water channels provided by the bottom disc when closed; or when open: diverts water from the holes of the bottom disc outwards to the radial holes in the cartridge housing. This water is then further diverted up and out of the tap for use.

The reason why it only takes a quarter turn to fully open the water channels of this type of cartridge: is due to the placement of holes and channels within these ceramic discs. The first (bottom) disc has two oppositely placed holes within it. Each taking up approximately a quarter section of the circular valve.

This quartering is then reflected within the top ceramic disc. Which consists of two opposing cupped flat plates, and two opposing angled wedges: which veer off to the radial holes within the brass cartridge housing. And since these channels take up opposing quarters of their discs – it only takes a quarter turn to either align both holes of the bottom plate with the upper disc’s water outlet ramps, which then allows water to pass; or with the flat plates, which then blocks the water at both holes.

Cartridge operation demo video

Valve operation demo video

Suction effect demo video

Dripping fault Analysis

Dripping fault cause theory

The fault that causes a dripping tap can be due to a number of different factors. Probably the most straight forward scenario includes water simply making it’s way around the rubber o-rings and/or water gasket. This could happen if the rubbers have gotten old or heat damaged, and started contracting or cracking as a result. Alternatively, they could’ve been disturbed or are otherwise not seated correctly in order to form an effective water barrier.

This means that whatever water does manage to get around these seals can then bypass the cartridge altogether and shortcut it’s way to the faucet head. The severity of the leak in this case would be directly proportionate to the ineffectiveness of the rubbers to seal out water.

Another issue could be within the cartridge itself. With water entering the cartridge and then passing through the cartridge valve by squeezing between the two ceramic disc plates due to an imperfect seal. This pressure fit seal between the two disc plates could be undermined by a number of different factors.

The most likely of which are a build up of limescale on the the ceramic discs themselves. Limescale is a broad term to encompass residual build up of the carbonates present in drinking water; such as calcium and magnesium carbonate. Water rich in minerals like this is often referred to as “hard water”.

Limescale build up on the contact surfaces between the ceramic discs, can cause them to then become uneven as the limescale adheres to them. Specifically the drip issue is caused because the valleys in this now uneven surface provide the water a small pathway across the pressure seal’s threshold when it is closed.

Another issue that could cause the valve to no longer function effectively is scoring of the inter-disc surface. Essentially scratches that then allow some water to pass through their valleys when the valve is closed. A likely cause of this could be something as basic as wear and tear. The two discs grinding each other down over an extended period period of time due to standard use. This happening with just the minor friction created from repeated opening and closing over time, eventually compromising the watertight seal as disc surface material is lost.

Before moving on, I should mention that this section is largely speculation. Basically educated guesses based on my observations during the disassembly. That being said these theories above are the one’s that I went into this repair with.

Dripping fault effect

A continuous drip may initially seem like a minor fault, because it is. However, this fault incurs a waste of resources. A slow but continuous one, that is hard to easily assess. Simply put it wastes water, and probably more than you might expect as well. Just because it only wastes a drop at a time, it doesn’t mean that it isn’t wasting a lot cumulatively. It just makes it difficult to easily see the totality of wastage.

Sampling methodology

Let’s try to get a rough idea of how much water is lost due to this fault. Note that this is not going to be very scientific. It is just a test to get a rough idea of water wastage. With that in mind, there are two discrete pieces of information that are required: 1) is the average water droplet volume; and 2) the number of water drips within a set period of time. In this case the sample time will be 1 minute.

I captured a single drop using a teaspoon. Then sampled it using a random plastic pipette that I had on hand. I repeated this a few times and found the droplets to be rather consistent in volume. Unfortunately, due to the pipette’s lack of precision, I was forced to visually estimate this volume between it’s labelled increments.

Collected observations

  • This leaky tap consistently provided around 13 drips within any one minute period.
  • With each drop having a volume of approximately 0.3 ml each.

Water drip rate and predictive volume lost

  • 1 minute: 13 drips @ 3.9 ml
  • 1 hour: 780 drips @ 234 ml
  • 1 day: 18720 drips @ 5616 ml (~5.6 litres)
  • 1 week: 131040 drips @ 39312 ml (~39 litres)
  • 1 month: 524160 drips @ 157248 ml (~157 litres)

Leaking faucet demo videos

Droplet sampling demo video

Leak conclusion

Interesting result. If a household either has a limited water supply (e.g. off-grid), or is on a metered supply where they pay for water by volume; then 157 litres lost in wastage in a single month by a single tap is not insignificant.

I hope this has illustrated how important it is to fix even minor faults such as this as soon as possible. 157 litres of water used could very well cost a metered household more money on the fault’s first month on the household’s monthly water consumption bill, than a complete cartridge replacement for that tap otherwise would have.

Repair process

Getting at the parts

First thing first. Common sense. I switched off the water by closing the main water valve for the house. This was located under the kitchen sink for me. This is an essential step in the same way as one would switch off the electricity before working on an electrical outlet, one needs to turn off the water before working on a water outlet. You’d think that was common sense right? But I have seen too many plumber fail videos online that say otherwise.

After giving the kitchen faucet a once over, and looking online I decided that the tap cartridges are the most likely suspects for the drip, so I set upon getting at them. Since I have never taken a kitchen sink tap apart before, I engaged in what I call an exploratory disassembly. Prodding and poking the device looking for hidden clips and screws.

To cut to the point: I used a nylon spudger to pry open the (metal coloured) plastic screw cover on each tap. I recommend using a plastic pry tool to avoid scratching the finish off of any part of the tap. Next. I unscrewed the phillips metal screws which attached each tap handle to the rotatable cartridge cylinder section below them. After setting aside the tap handles, I then removed the full cartridge assembly from the faucet housing using a wrench. As for disassembling the cartridges themselves, they come apart toolessly in-hand. That’s it. Easy.

Inspection

Like every repair, this one begun with a thorough inspection. A basic visual inspection did not reveal anything obviously wrong with either cartridge to my eyes. However once I disassembled both hot and cold units, I noticed that the internal plastic disc valves on the cold water side felt rough to the touch. Likely indicating a build up of limescale. Most notably this was even apparent on the surfaces between the two valves. And since these two surfaces come together to form the press fit seal that controls water flow: I concluded that this was likely the specific cause to this particular leak.

Limescale build up is nothing unusual for my particular location, as I do live in a heavy water area. However the odd part was that all the limescale build up was on the cold water side cartridge of our kitchen tap. With little to none on the hot water cartridge. This is really unusual in my opinion because I believe that higher temperatures should exacerbate limescale build up. The average water kettle should be a testament to this theory. However in this case the limescale build up was only sufficiently present on the cold water side.

A working theory I have concerns the on demand water heater which directly supplies this tap – a boiler which my household recently (1.5 years) had professionally installed. I believe that it has some-kind of water filter (or softener, or descaler…) that has been fitted to minimize limescale build up within the unit as it heats water. This means that the hot water provided by it to the tap would have less mineral contaminants (i.e. be softer) than the cold side. I would verify this, but it is not a pressing issue and not worth digging the unit out at this moment to confirm.

Cleaning the cartridge

Once I decided that it was limescale that was undermining the valves press-fit seal, I decided to take the already disassembled cartridges and submerged them into a vinegar solution. The idea is that the mild acid of vinegar will react with the alkaline limescale and dissolve it into the liquid solution.

After about an hour, I removed the parts and brushed them all down with a basic toothbrush in order to remove any loosened remaining debris. I did however take care not to scratch or score the plastic valves as any scoring would also undermine their ability to form a watertight seal; as this would allow water would pass through the miniscule divots that would be present on the seal’s contacting surfaces.

With regards to this method, I should note that I made exceptions for the rubber parts of the cartridges. The blue o-rings and red/blue rubber gasket. I just did not feel comfortable submerging them in an acidic solution for extended periods. I feared that it may affect the chemistry of the rubber material and ‘dry’ it out. Thus causing it to crack or split; and consequently be no longer effective as a waterproof seal. (FYI the pictures below are lying.)

Testing

After a quick rinse in tap water I decided to reassemble the cartridges and put them back into service for extended testing. Although the leaking was significantly reduced as it didn’t drip continuously as before: it still dripped regularly. This was tested by leaving an empty cup under the tap head overnight. I’d regularly find the typical coffee cup I used at least half-full come morning.

This lead me to surmise a number of scenarios:

1) That the water was making it in between the the plastic valve seals. Likely due to surface scoring caused by either my cleaning/brushing of the valve discs; or the limescale itself being ground into the discs as they operated over the years.

2) Water is making it’s way around the gaskets and o-rings, in addition to bypassing the valves. And that I have only remedied/alleviated one issue.

Greasing the cartridge components

With these conclusions I decided to then purchase some plumber’s grease. Thinking that it would be perfect for the application of assisting the plastic disc valves and rubber gaskets to form water tight seals. The Ebay listing for it explicitly stated just that.

However once the product arrived, I decided that I wouldn’t be testing it’s efficacy as I decided that it was not fit for use. The reason why: was that the little tin came with a whole host of warnings on it’s label. Warnings typically associated with poisonous chemical products.

Particularly the “Do not eat, drink, or smoke …” around this product warning gave me pause. Especially when coupled with the fact that the very vapours from this thing were an irritant. It emitted a vapour that was a mild irritant to the eyes and nose, smelling almost minty like the ointment “tiger balm”.

So despite the labelling assuring me that it is indeed appropriate for use within water faucets, I decided that this was not something that I wanted coming in contact with my drinking water – and ultimately ending up inside me. Maybe I am just paranoid. Maybe not.

Either way if an irritant chemical has warnings not to ingest it, and by using it for it’s intended purpose you are essentially guaranteeing ingestion. Maybe don’t use that chemical. Ultimately, it all just comes down to personal choice, and how much you trust anonymous Ebay sellers over your own intuition.

Personally I just found a substitute: Petroleum Jelly. A non irritant, non toxic chemical that routinely comes in contact with human skin and lips. So chances are good that it won’t do any harm if you accidentally ingest some with your drinking water.

Additionally unlike the plumber’s grease, the jelly can be used with rubbers like the o-rings and gaskets. I used to use some back in school within the science lab. A small amount was applied to the mouth of a bunsen burner’s rubber gas hose in order to help form a gas-tight seal between it and it’s brass attachment. I remember it even hydrating the dry red rubber of those hoses. Although I am pretty sure that petroleum jelly is also flammable so I’m not sure if that was a particularly safe application for it. :/

However within this application: my only concern with petroleum jelly is it’s longevity in the system, and heat resistance. However those are considerably less concerning than putting poison in a drinking tap. So after greasing everything up: the o-rings, the rubber gasket, and the plastic valve discs, then tighten everything down properly – I did note further improvement. Now the faucet barely leaks at all. Barely being the keyword here.

Jobs a gudd’un mate.

Post repair review

I left some time after the repair for observation before writing this review and it seems the leak is slowly returning after a month. A month of constant use keep in mind. I am still chalking it up as a success because this repair really only needed some basic tools and materials. The only consumables used are just household sundries like vinegar and pure petroleum jelly. So it can be done for next to nothing.

There are even more things I could do short of purchasing replacement cartridges, and that would be to use an additional o-ring under the main water ingress rubber gasket. This will put more pressure on the plastic disc valves. Squashing them together to form an even tighter pressure fit seal between them.

Although there are likely drawbacks to this, including and not limited to: firstly, a stiffer tap – the more downward pressure on the cartridge mechanism, the harder it would be to rotate it; and secondly, the higher pressure on the discs themselves would cause them to grind against each other more, and likely shorten their lifespan by promoting scraping of their contact surfaces.

Although if you are repairing it in the first place, chances are that they are already well towards their end-of-life, in which case this fix will extend it couple of months before they likely fail into a unrepairable state. At which point replacing the ceramic discs will be needed. Just my guess.

Closing thoughts

Not much to say here really, I surmised my thoughts on the repair itself within the Post repair review above. So I’ll go with a more personal note here.

I actually enjoyed looking at this tap cartridge more than I thought I would. It really is amazing what people are capable of creating through iterative design and mass production. It reminds me of the gaming concept of min-maxing: of getting the most out of the lest.

I mean look at the simple design and construction of this cartridge. It uses two plastic/ceramic discs to create a watertight seal by just pressing against each other. Undoubtedly the results of iterative cost cutting to the point of being adequate or acceptable, and little more.

I know that when I usually talk about cost cutting, especially when discussing mass produced goods: its usually in a negative light. That’s because the stimuli or catalyst for those tangential rants tends to be a product that is sub par, and in my opinion not fit for purpose. Products that I refer to as “factory fresh e-waste”.

However that is not the case here, these cartridges are fit for purpose. But they are also (in my humble opinion) built down to a price point. One that makes economical sense. Look at the bill of materials here for example: a brass housing and insert, a retaining clip for the insert, a metal washer, two o-rings, a water gasket, a metal screw, two plastic/ceramic discs, and maybe one or two additional miniscule hidden parts that I missed. That is a list that has been reduced to the absolute necessities and little more, but nothing less either. I admire the philosophy honestly.

Anyway, enough gushing about the tap. Since I repaired it: it’ll do that itself in a year or two ;). Upon looking up the Ebay prices for replacements, I noticed that they are very cheap. (At least the generic versions.) The average price for a set of two is £10; and if you wanted to repair your own two cartridges with a kit of replacement o-rings, gaskets, and ceramic discs, then that’ll set you back around £2.50. Very doable.

As a final note, if you found yourself confused as to why I kept referring to the cartridge discs as both made out of plastic and ceramic. Well, this is because the unit I was working on (pictured) felt like plastic to me. A hard somewhat brittle plastic.

However upon looking them up online, apparently they are all ceramic. I also wrote the repair section during the repair process prior to this; and I decided to leave it as plastic because that’s what I felt that material was while I was handling it. Although I am by no means an expert on such things, if the internet says that it’s ceramic then I guess it likely is.

Thank you for reading.

Links, references, and further reading

https://en.wikipedia.org/wiki/Hard_water

#0026: Preventative maintenance for laptop computers

Otto

#0026: Preventative maintenance for laptop computers

Preamble

This will be a brief guide to maintaining the hardware of a laptop computer. This is with the intent to prevent the breakdowns and computational performance loss, that is resultant of extended user negligence. It is pretty much a cleaning guide, including: necessary tools, materials, tests, parts descriptions, general methodology, and background information. This is provided with the aim to bring unmaintained units into a workable state. Although I specify this guide for laptops, most of the techniques discussed can apply to any computer. This includes: desktop PCs, game consoles, or servers. The core ideas discussed here have more-or-less universal application.

What causes negligence related breakdowns?

The short answer is that this type of breakdown, is caused by the overheating and eventual burnout of computer components. This overheating is due to the diminishing effectiveness of the machine’s cooling system over time. Although a laptop’s cooling system consists of several contiguous parts, there are only three main parts that require any degree of special attention. These are: the heatsink fins, the fan, and the thermal transfer material (thermal pads/paste).

Where is heat created within a computer?

Although technically most semiconductors can create heat when operating, there are only a few components that create enough heat to warrant the use of a cooling apparatus. These include: the CPU (Central Processing Unit), the GPU (Graphics Processing Unit), and in high power systems, this even includes the voltage regulator modules that supply these processing units.

It should be noted that any given laptop’s cooling system is already configured to attach to all the components that actually need cooling. It was configured to do so at the designed stage of product manufacture. So there is no sense in worrying about the heat output of any components that aren’t covered by the default cooling system that the laptop already has.

Laptop cooling system explained

Cooling plate: This is the initial heatsink that conducts heat out from the chips and into the heat pipes.

Heat pipes: Heat pipes are good at transferring heat from one end of the pipe to the other quickly. They do this by being filled with a liquid that evaporates and condenses readily within the pipe’s sealed system. The general idea here is that the liquid evaporates into gas on the hot side, causing it to quickly travel to the cooler side where it condenses back into liquid as it loses it’s energy to the surrounding material.

Heatsink: Heatsinks have fins that are designed to have as much surface area as possible between metal and air. This is to facilitate the convection of heat out of the cooling system and into the environment.

Blower fan: The blower fan is exactly that. It blows the hot air that the heatsink fins have warmed up, out and away from the computer. This is to maintain a constant temperature gradient, that facilitates heat energy moving out of the heatsink fins.

Why is maintaining a cooling system especially important in laptops?

The main reason why maintaining the cooling system is especially important within laptop computers over for example desktop computers, is that often the cooling system on a laptop is barely adequate for it’s computer’s needs as it is; bran new. As such, any additional degeneration in cooler system efficiency may quickly effect performance. The reason why many cooling systems can barely dissipate the heat produced by their onboard CPU and GPU is two fold.

One, laptops have a significant size limitation that desktop computers do not have. Every component that would go into a typical desktop computer, has to fit into the significantly smaller profile of a laptop. This unfortunately includes the cooling system, whose effectiveness directly correlates with size. Bigger heatsinks, sink more heat; more heat pipes, can move more heat concurrently; and bigger fans move more air. It is as simple as that. Additionally, the current market trend of making laptops thinner and lighter is exacerbating this issue.

Two, the role of the modern laptop is different than what it once was. Modern laptops have higher power requirements than ever before. This is due to them housing more powerful CPUs then ever before. CPUs which generate more heat than ever before, heat which needs to be dissipated.

Modern laptop computers have moved beyond the realm of earlier notebooks; i.e. machines designed for web browsing and clerical work. With the introduction of gaming laptops and desktop replacements, we now high performance machines; genuine portable alternatives to full desktop computers. Many of which housing CPUs comparable with their desktop counterparts. The only unfortunate part is that they don’t have the same level of cooling available. Therefore maintaining the efficacy of the cooling system that is does have is that much more important because of that.

Example of a laptop with an underdeveloped cooling system

I have in my possession a Toshiba Satellite P850 that I purchased new around 2012. This particular machine came with a socketed CPU (i.e. replaceable), and at the time of purchase I recall having to specify whether I wanted an Intel i3, i5, or i7 CPU installed. Three very different CPUs in terms of computational ability and heat output. Yet the rest of the computer was of the same design, including the built-in cooling system. I purchased the most powerful i7 package option, and consequently have always had heat related issues with the machine; having to even augment the built in cooling system with an external “laptop cooler pad” to avoid overheating when under extended loads (e.g. playing video games).

post maintenance temperature statistics for Toshiba Satellite P850 laptop (note: bottom two temps are irrelevant as they are HDDs)

Symptoms and explanations of laptops with poor cooling

Symptom list:

  • The machine is generally dirty.
  • Heatsink fins blocked up with dust, grease, food, or grime.
  • Loud fan: fan operating constantly on full throttle.
  • Fan notably vibrating or making clicking noises.
  • Fan not spinning freely (i.e. noticeably struggling to spin).
  • No fan noise at all.
  • High localised radiant heat.
  • Drop in CPU performance when under load.
  • Diagnostic software reading high operating temperatures at idle state.
  • No thermal paste present between the cooling plate and CPU.
  • Dry or hard thermal paste present between the cooling plate and CPU.

Explanations:

  • The machine is generally dirty.

If on a basic visual inspection the machine is externally dirty, it is likely to be in a similar state internally. Since dirt and dust are generally good thermal insulators, they’ll assist the machine in retaining unwanted heat energy. Additionally, general cleanliness is also a good indicator as to the level of maintenance the computer has been subjected to.

  • Heatsink fins blocked up with dust, grease, food, or grime.

Heatsinks require large surface areas, in order to transfer heat energy effectively from themselves and into the immediate local environment. In this case: air. This is done via a process called thermal convection. Heatsinks achieve their large surface area (relative to mass) by employing heat-fins. Row upon row, of often wafer thin plates that maximise the heatsink’s contact with the air around it.

In order for the heat exchange process to operate effectively: air must be allowed to move freely between the heatsink’s fins and contact it’s surfaces without obstruction. Additionally, the constant movement and renewal of the air through the heat fins maintains a thermal gradient that keeps heat energy moving out of the heatsink and into the local air. If airflow is blocked for whatever reason. Then sooner or later, the heatsink will reach a level of thermal equilibrium with the local pocket of air around it, at which point no more heat transfer will occur.

  • Loud fan: fan operating constantly on full throttle.

During normal operation, a computer will modulate the revolutions of it’s cooling fan(s) in order to maintain a stable system temperature. This modulation includes: raising the fan rev speed to decrease temperatures when necessary, and lowering fan rev speed to reduce fan noise once safe temperatures have been achieved. If the computer fan is spinning loudly at full rev continuously, it is indicative of the system sensing the presence of a consistently high temperature.

  • Fan notably vibrating or making clicking noises.

Fans vibrating or making clicking noises is a possible indicator of an issue with the fan bearings. Such as misaligned or dry bearings. This generally makes the fan spin slower than intended, or suddenly stop for a period of time, before resuming spinning as before.

This issue is twofold. One, that fan will not be able to adjust it’s rev speed to match the system’s needs in time. This is due to the unaccounted for resistance to rotation that it will encounter in it’s current state. Two, when it does spin, it risks getting stuck perhaps permanently. When electric motors like the one in these types of fans get stuck, they take more and more electric current. If it doesn’t start spinning soon, it risks overheating the motor coils and burning itself out.

A clicking fan needs to be removed, disassembled, then inspected. If it’s bearings are merely dry, then they can be re-lubricated. The fan may work fine after this. If however the bearings are damaged, then either they’ll have to replaced; or alternatively: you may have better luck simply replacing the whole fan assembly. Additionally, a strictly vibrating fan will also have to be disassembled and inspected. In this case: look for anything that may make it spin off kilter, such as a bent or misaligned central shaft or blade hub.

  • Fan not spinning freely (i.e. noticeably struggling to spin).

A sticky motor struggling to spin could be caused by anything; from hair or dust wrapped around or caked onto the central shaft of the electric motor, to the fan bearings drying out. Since a stuck motor pulls more current than a spinning motor, it also generates more heat. This heat will eventually destroy the motor. Clean the fan thoroughly and test it. If it still struggles to spin. Then disassemble it for inspection.

  • No fan noise at all.

If you have no fan noise what so ever, then chances are that the fan isn’t spinning at all. Check that it isn’t stuck, or burnt out. It should be noted that: a laptop’s cooling system needs an active air current running through it to remove the residual heat. The passive cooling components alone are often not sufficient to dissipate the heat, at least without having something to actually expel that heat from the system. With that in mind, replace or repair the fan as soon as possible.

  • High localised radiant heat.

High localised radiant heat near the source indicates that the heat isn’t being dissipated from the source quick enough. I.e. there is likely a break somewhere within the cooling system that prevents the heat energy from travelling away from the source.

  • Drop in CPU performance when under load.

Many CPUs or systems, have a thermal throttling feature where they actively limit the processing capabilities of the CPU. This is in order to limit it’s resultant heat output. Usually machines don’t limit their CPU performances in this way, unless the cooling system is proven inadequate. In order for a CPU to start thermal throttling, it needs to reach a threshold temperature that is considered potentially dangerous to the CPU itself.

  • Diagnostic software reading high operating temperatures at idle state.

Diagnostic software like Speccy and Psensor can be used to display information from the built-in system temperature sensors. Assuming an ambient temperature of approximately 20 degrees celsius: CPU temperature readings above 60-70 degrees celsius on an idle system is indicative of a poor cooling system. Additionally when the system is actually under load (i.e. doing work), these temperatures can spike to 80-90 degrees. Reaching the thermal throttling thresholds.

  • No thermal paste present between the cooling plate and CPU.

Thermal paste is a heat conductive layer between the CPU and the cooling plate (or heat sink). It is necessary to enable the most efficient conductive transfer of heat possible out of the CPU and into the cooling system. Although technically, computers can operate without thermal paste. It is not recommended, especially in higher wattage systems with more powerful CPUs. CPUs which can reach very high temperatures very quickly.

You could probably get away with not using any thermal paste on a really low power system. For example with my 2009 HP Mini 110 laptop, which has an intel atom processor inside it. Since that CPU can’t really generate enough heat to be concern. Still I wouldn’t recommend it. Now that I think about it: the only real time I ever came across a machine without any thermal paste applied, was when I purchased a “seller refurbished” unit. I.e. basically due to human error.

  • Dry or hard thermal paste present between the cooling plate and CPU.

As thermal paste ages it many become: hard, dry, and brittle where it was once a pliable soft paste. This new state means that it can no longer do it’s role of filling in the miniscule gaps between the cooling plate (heatsink) and the CPU. It also diminishes it’s effectiveness at conducting heat, due to the air gaps it likely to develop as it dries out.

Tooling

This is a small list of tools and optional alternatives to the one listed above it.

Tools:

  • clean cloth
  • bristly brush (nylon paintbrush)
  • (optional) vacuum cleaner
  • (optional) compressed air

Materials:

  • cotton earbuds
  • (optional) tissue paper
  • isopropyl alcohol
  • (optional) alcohol wipes
  • (optional) rubbing alcohol
  • thermal pads

Maintenance

Summary:

  • replace thermal paste if it is dry or contaminated with anything (e.g. dirt)
  • replace (or clean) any thermal pads that my be contaminated
  • clean out the heatsink fins with a brush
  • clean out the fan with a brush
  • make sure the fan spins freely

Specifics:

Cleaning off thermal paste

Thermal past is easy enough to remove. All you need is a tissue or an earbud dipped in isopropyl alcohol. Just carefully wipe all the residue off. Then give a final pass to make sure you remove any errant cotton/tissue fibres.

Cleaning thermal pads

Sometimes you may come across thermal pads on certain secondary chipsets around the cooling plate. These pads may be of various thickness to cover the variable gaps between the chips’ height and the cooler plate above it. Because of this it may be somewhat difficult to find appropriate replacement thermal pads.

In this case cleaning and reusing the stock thermal pads is a decent alternative. A good wiping down with an alcohol soaked tissue to remove any dust and foreign debris on the stock pads is sufficient to reuse it. Since traditionally thermal pads (especially the thicker pads) are used for chips that although produce heat, they don’t produce enough to warrant special attention. As such getting a fresh replacement for each chip is not critical.

Cleaning out heatsink fins

Using a stiff paintbrush, wipe out all the dust and debris by following the lines of the fins. With heat-fin tunnels, if they are short: stab the bristles of the paintbrush into it at both openings. Otherwise you may require air to clean long tunnels properly. Either use compressed air or a vacuum cleaner to blow or suck the dust out respectively.

If however the heatsink fin tunnels are blocked up with something sticky, like grease or dried residue from a sugary drink. Then actually immersing the entire heatsink in warm soapy water and washing it will be necessary. Just make sure it is absolutely dry before putting it back into the machine.

Applying new thermal paste

Generally I find that users need less thermal paste than what they may initially think. All you need for thermal paste is to have enough to sandwich between the cooling plate and the CPU die. All thermal paste does is smooth out the imperfections within the cooler plate surface, and fill in the small gaps between the plate/heatsink and the CPU. It does so to maximise thermal conduction by reducing the effect of the barriers between the materials. That’s all.

I find that about a pea sized amount for an average sized CPU is good enough. I also like to use a spreader to make sure that all the corners of the CPU die are adequately covered, before I mount the heatsink on. Although putting on too much paste (within reason) doesn’t really affect performance or anything. It just squeezes out from between the cooler plate and CPU, as it is tightened on.

Closing thoughts

I am genuinely surprised that I managed to write so much for what could adequately be summed up with two sentences: “Clean the damn thing! It’ll live longer.” However I think that an actual breakdown and identification of the types of faults that a laptop could develop if left uncared for, and why preventative maintenance for laptop computers is especially important: is what really gives this article some value. I hope it makes average users, regardless of skill level understand the importance of preventative maintenance and recognise some of the symptoms of when it is time to open up their computer and give it a good clean and freshening up.

Probably the biggest hurdle I think the average user would have is applying new thermal paste to a CPU. If you are in anyway daunted by the process, just keep these points in mind. One, CPUs are not made of glass (or are they?), they aren’t that fragile. Just be careful, move mindfully, and you likely won’t damage it. Also it’s good protocol to ground your hands before handling sensitive electronics. Something as simple as touching a metal chassis of a plugged in appliance would do it. This is to help prevent any electro-static discharge.

Two. Thermal paste is not expensive, don’t be afraid to “waste” some practising applying it elsewhere. Also thermal pastes are all pretty much the same stuff. Don’t worry about brand differences. Chances are you are not overclocking, so you don’t need to worry about the specialist materials like liquid metal, or the performance differences between various expensive named brand pastes. Just buy whatever you can get in your budget, and use that. It’ll do the job.

Ultimately, there really is no excuse for not cleaning your machines. Remember: take care of your tools, and they’ll be around to take care of you.

Thank you for reading.

Links, references, and further reading.

https://en.wikipedia.org/wiki/Fin_(extended_surface)
https://en.wikipedia.org/wiki/Heat_sink
https://en.wikipedia.org/wiki/Convection
https://en.wikipedia.org/wiki/Convection_(heat_transfer)
https://en.wikipedia.org/wiki/Thermal_conduction
https://en.wikipedia.org/wiki/Semiconductor
https://www.pcgamer.com/this-detailed-breakdown-of-a-high-end-motherboard-is-pretty-awesome/
https://www.tomshardware.com/reviews/vrm-voltage-regulator-module-definition,5771.html
https://www.maketecheasier.com/what-is-vapor-chamber-cooling/
http://www.nuclear-power.net/wp-content/uploads/2017/11/Convection-Convective-Heat-Transfer-comparison-min.png

#0023: Repairing short circuit damage within a ribbon cable

Otto

#0023: Repairing short circuit damage within a ribbon cable

Preamble

Sometimes you might come across damage within a ribbon cable similar to the example. The minor burn damage on the example featured was done by a liquid causing a short circuit between two exposed copper pads. As it burned, it created a break between an exposed pad, and it’s respective trace. Cutting the circuit in the process. The short also caused some of the other pads to oxidise, and some minor burning of the ribbon cable’s plastics. This will be a quick tutorial on repairing such a fault.

Please note: I have no images before the initial cleaning and prepping stage. This is because I was halfway through this repair, when I decided that it may be good to document it.

Tools and materials:

  • scalpel
  • tweezers
  • isopropyl alcohol
  • cotton earbuds
  • soldering iron
  • lead solder
  • copper strand from a wire
  • side cutters
  • multimeter

Step 1: Identifying and logging the damages

This should always be a first step before attempting a repair. The reason for this is that the initial pre-work cleaning, is likely to clean away a lot of contextual clues about the location and severity of all the damages. A good visual inspection and initial assessment can save time later on, due to not having to track down any circuit damage that got masked or hidden by cleaning.

Step 2: Cleaning the local area

First thing I did after identifying the location of any potential damage I wanted to repair, was to clean it. In this case I needed to first scrape off the more obvious patches of oxidation and burnt/melted materials using a scalpel. Then thoroughly clean off the pads of the ribbon cable using isopropyl alcohol and a cotton earbud. I paid special attention to the tiny burn hole next to the most damaged pad, making sure to remove any conductive materials from it by scraping it out thoroughly.

Step 3: Test to confirm faults

Using a multimeter in continuity mode, I tested for continuity between the pads surrounding the burnt spot. Perhaps it still contained conductors (such as pieces of the broken pad) that may cause a future short. After being satisfied that it did not; I focused on the particular pad that sustained the most damage, and tested for continuity across this pad and it’s respective trace to see if it was still connected. It was not. All other pads had continuity with their respective traces.

Step 4: Fixing confirmed faults

After identifying only a single fault; this being a break between a pad and it’s trace. I moved to repair it. Firstly I endeavoured to bridge the gap by just tinning across it from the pad to it’s trace. The thought process was that that the mere mass of the solder itself would be enough to bridge the tiny gap. It did not. After that initial failure, I decided that I required a bridging medium; something for the solder to adhere to. In this case I decided to use a single copper strand from a wire.

Using a scalpel, I removed some insulation from the ribbon cable trace above the broken pad. This was in order to have something on that side to comfortably solder the copper strand to. After which, I soldered the wire whilst using a pair of tweezers to hold the tiny copper strand down in place.

Step 5: Cleaning up after a repair

The next step involves cleaning up any messes I might’ve caused during the repair. In this case, whilst trying to initially tin the broken pad, I also tinned the neighbouring pads accidentally. In trying to remove the bulk of the solder, I caused further damage by starting to burn the plastic that the pads are set into. In the end I decided to just leave it be. The repair needed to be functional, not aesthetically pleasing. I did consider using a desoldering braid to remove all the solder, however I was very likely to cause more damage trying, so I opted to just leave it be.

In the end the after-fix clean consisted of just clipping off the excess wire with a side cutter and cleaning off any flux residue with an isopropyl dipped cotton earbud.

Please note: There is no electrical connection between adjacent pads. The burnt plastic between the pads just looks like solder. I told ya it was ugly.

Step 6: Testing the repair

Next. I performed a quick continuity test on the repair with a multimeter; both testing for continuity across the pad to it’s trace; and testing for a lack of continuity across neighbouring pads. These tests take basically no time to do and can set my mind at ease. I do these types of tests even when a visual inspection indicates that it’s not necessary.

The real test is putting the device back into service and seeing if it functions as expected. In this case the ribbon cable that I repaired was from a laptop’s integrated keyboard. Although the ribbon cable fitted more snugly into it’s receptacle or socket than I wanted. It still fitted and functioned properly. The keyboard was fully functional after this repair. Huzzah!

Closing thoughts

I apologise if this article came off as a little patronising; especially given the quality of the example repair, the missing “before” picture, and the fact that it contains mistakes front and centre. Generally, I find step-by-step guides like this one difficult to write, without sounding either needlessly pedantic or excessively didactic. Anyway, even if the exact specifics are not useful to you, I hope the general steps would be. Identify. Clean. Test. Fix. Clean. Test. Then Profit. That is if it works, if not: then go back to testing for faults.

Thank you for reading.

#0021: Repairing an LCD with missing segments

Otto

#0021: Repairing an LCD with missing segments

Preamble

This is a quick guide to repairing a specific fault found on undamaged low information monochrome numerical LCDs. Such the ones present within calculators. As such it will not go into detail about the functioning of LCDs in general, types of LCDs available, or any other information outside of the scope of simply repairing the missing displayed segments fault.

What is an LCD?

An LCD or Liquid Crystal Display, is a type of flat panel display. At its most basic an LCD operates by using the properties of liquid crystals coupled with polarisers. Polarisers are a type of optical filter that only allow light waves to funnel through them in a particular orientation. In other words, they remove light scatter; only allowing it through in a uniform manner. This, coupled with the liquid crystals’ property of altering their physical orientation when in the presence of an electric current; means that the narrow beams of light that make it into the crystal solution can either be allowed to pass through, or blocked, depending on the orientation of the crystals within the solution.

The specific type of LCDs we are dealing with are low information monochrome single line seven-segment displays. These types of simple LCDs are typically used in devices that predominantly output numbers. But may also display static symbols, such as the “E” in calculators for numbers that are too large to display without index notations. These types of LCDs are most commonly associated with pocket calculators. However they have been used with such devices as: alarm clocks, multimeters, solar charge controllers, battery monitors, household mains electricity meters; and I have even seen them used as a display on an electronic keypad lock.

I think this type of LCDs popularity is mostly due to it’s relative simplicity and low operating costs. It follows the KISS design philosophy. Keep It Simple Stupid. If a device would not notably benefit from a more complicated display, if all that it displays are simple numbers and basic symbols; then there is little reason to incur the (production and operating) costs of increasing design sophistication beyond this type of display.

As for the mechanics of how liquid crystals work, I like to (keyword) imagine a matrix of magnetic rods. At rest, the viewer can only see them from the top, and considering their microscopic size, this renders them essentially invisible. Whereas when a current is passed through them, the entire matrix of rod shaped crystals reorientate themselves to reveal the entire length of each of the rods. This greater surface area against the polarised light from the viewing angle, makes them appear opaque. There’s more to it than that, but that’s the general mental model I use to conceptualise the process. Although strictly speaking it isn’t accurate.

So how does a basic monochrome seven-segment LCD actually display information?

An LCD of this type is mapped with discrete segments. These primarily consist of seven dashes arranged in a number ‘8’ pattern. These are the core seven segments that are used to display numbers. Additionally LCDs have segments in the shape of static symbols; such as a period on calculator, or a colon on an digital clock.

Every discrete segment is given a set of electric probes. These probes are designed to allow a current to pass across the segment’s liquid crystals. This is how the liquid crystals within each individual segments are switched on and off. It operates in an analogous way to seven-segment LED displays. I.e. they both require an a electric current to be passed across each individual segment in order to activate it. Additionally, this electric current is controlled by a display controller IC (Integrated Circuit). Which translates any numerical values into display data (active segment and inactive segment map) that it uses to power it’s display accordingly.

example of an LED display
LCD segment map
segment circuit animation

Missing segments fault (on undamaged LCDs)

First of all, I specify that the LCD is undamaged because if the LCD you are attempting to repair is damaged, (e.g. has a crack across it); then chances are this fault is not the major contributor to your LCD’s malfunctions. That being said, missing segments on undamaged LCDs are likely caused by a break in the particular missing segment’s individual electric circuit supplying it.

Earlier I likened LCD seven-segment displays to their LED counterparts. This is because both require an individual IC controlled circuit that connects with each discrete display segment. Its just that with LEDs, its a lot easier for people to understand what is happening, when some of a displayed number’s LED segments fail to turn on. The failure to activate can be intuited due to a break in it’s branch of the circuit.

In this case the break in the segment’s circuit is usually caused between the LCD module and the underlying PCB; which hosts all device circuitry, including the display controller. This break usually occurs within or around the bridging material between the LCD and PCB. Namely the elastomeric connector (trade name: “Zebra strip”). This black and pink rubber like material is a soft electric conductive material that conducts electric signals across the naked pads of the PCB to the LCD and vice versa. It does this by having many tiny channels (or layers) of conductors and insulators, that alternate across it’s black strip. This black strip is then sandwiched with a pink insulator that runs the length of the outer sides of the elastomeric strip. This configuration allows the elastomeric strip to act like a large assortment of miniscule wires that electrically connect together whatever pads or traces that they touch at either of their ends.

The circuit break in this missing segments fault could be caused by two main things. Firstly, it could be due to an electric insulator getting in between the elastomeric strip and the exposed pads of the LCD and PCB. This could come in the form of a build up dust or grim, or even oxidation of the exposed PCB pads. To repair this, just clean all the pads and the elastomeric strip itself. I recommend using isopropyl alcohol and a cotton ear bud or cue tip. Just saturate the bud with the alcohol and scrub until it’s clean. Then reassemble the device and test.

Alternatively, this fault could also be caused by a separation between the elastomeric connector and it’s adjoining contacts. I.e. it has lifted off or away from the pads that is it supposed to be pressed against. This is usually caused by vibration. Typically, there will be a method of mechanically tightening or pressing the elastomeric connector against it’s pads. Such as a screw or adhesive, which with time and vibration (and maybe a little heat) can become undone enough that it allows the connector enough space to move away from it’s pads. To repair this, just re-tighten the screw or re-secure the elastomeric connector with tape if needs be.

The fault in the case with the example unit; I believe was caused by both a build up of dust between the contacts and the elastomeric connector, and also the connector physically separating from the LCD. The separation was caused by a loosening of the self tapping screws which held in place a bracing bar. This bracing bar applied pressure to the assembly consisting of the PCB, strip, and LCD, which sandwiched them together and kept them in place. That got loose, the strip moved slightly, and then dust got into the gaps that it created. After a good cleaning and tightening, it now works flawlessly.

Closing thoughts

When it comes right down to it, this is as simple as a repair really gets. No replacement of parts; just a basic disassembly and cleaning. It is essentially maintenance.

In my opinion, this type of repair is especially good for an aspiring repair tech with no confidence. The tools needed are basic, there are no additional parts (i.e. expenses) required, and the device being worked on it likely inexpensive; so there should be little in the way of consequences of failure. Such as fear of damaging a device, which may put people off from just ‘aving a go. Essentially the repair has little in the way of friction that may prevent a person from trying. It a good confidence builder.

Lastly, I just wanted to raise awareness encase you ever come across this type of fault in the future. It is easily repairable; and hopefully you’d be more inclined to at least give it a go, rather than discard the unit and purchase a new one as is usually the case for these types of cheaper mass market products.

Th-th-th-th-that’s all folks!
Thanks for reading.

#0020: Plastic welding techniques

Otto

#0020: Plastic welding techniques

Preamble

This is an introductory tutorial on welding plastics. The goal of this tutorial is to be a rather brief yet sufficient guide, that will allow the reader to be able to weld shut cracks and holes in plastic containers to the point of being water tight. It will cover welding technique, tooling, plastic types, PPE, and best practices. Everything an aspirant will need to effectively weld plastic containers.

Tools and materials

Tooling:

  • temperature controlled soldering iron or gun
  • (optional) fan

Materials:

  • appropriate donor plastic strips
  • (optional) duct tape or electrical tape

Personal Protective Equipment:

  • safety glasses
  • filter mask
  • thin rubber gloves

Core tool summary

As you can see the core tools and materials list is tiny. All you really need is a hot piece of metal to melt the plastic; and donor plastic material to flow into the various cracks and holes. This material is to reinforce and buttress the affected areas against any structural stress. That’s it.

Temperature controlled soldering iron

I specify a temperature controlled soldering iron (or gun) because you actually need relatively low temperatures to weld plastic; just enough to melt it, but not enough to burn the material. Most thermoregulated soldering irons would be too hot, because they are specced for melting solder. A material that generally has a higher melting point than many plastics. If the your iron is glowing red (even a little bit), then it’s probably a couple of hundred degrees (celsius) too hot.

Additionally, it would be beneficial if the soldering iron had a large thermal mass to enable it to maintain a stable temperature whilst it is in active use. I.e. actively transferring heat into the workpiece. A bit with a large surface area will also be useful, this is to effectively melt a good area of material at a time. Working with smaller bits makes the job more tedious. A smaller bit also concentrates the heat across a smaller surface area, which could cause heat spikes in the workpiece and consequently burn the local plastic. For the reasons above are why I chose to use a soldering gun with it’s widest tip rather than my usual general purpose soldering iron.

Plastic donor material

There’s not actually much to say about this. I like to make sure that the donor plastic is the same type of plastic as the item under repair is made of. This is to assist them in chemically bonding together more effectively. If you don’t want to purchase plastic donor strips like I have; you can alternatively just cut up similar items (i.e. items made from the same material) and use that. I have also seen many people use zip-ties as a donor plastic due to their convenient strip shape.

When selecting a donor plastic, look for a recycling symbol on the donor item (e.g. water bottle). Here it should have a few letters under it. These indicate what type of plastic the item is made from. Another thing to keep in mind when selecting a donor plastic is the food grade safety factor. To know whether or not a container is food safe, look for the knife and fork symbol. Specifically, when repairing a food grade container: do not assume that just because the donor plastic is the same type, as the food grade plastic container; that the donor is also food grade. Even if it initially is, the repair itself my change the chemical structure of the plastic to the point that it will now leech into any food (or drink) stored in it.

A good example is the container I repaired for this article. It was initially a food safe box, but now after the repair, even though it is now watertight again and I repaired it with the same type of plastic (PP); I would not use it for food, for fear of it leeching toxins into my foodstuffs.

common plastic types:

  • PET (Polyethylene Terephthalate) typically used in water bottles
  • PP (Polypropylene) general use plastic for containers
  • HDPE (High-density Polyethylene) typically used in milk bottles

Additional tools

Apart from the essentials, a fan will also help; both to blow any toxic plastic fumes away from you and to help cool the piece quickly as you work on it. Sometimes I find that as I work, an entire section of the container can suddenly soften to the point of almost liquefying, meaning that I will have to wait until it reconstitutes somewhat before work can continue. This however is an excellent state for moulding the pliable material to seal any cracks. Other than that, some duct tape may be useful to make the repair look more presentable and to give it a little more structural strength after a complete repair. Tape can also be used to hold the piece in place, as you weld the cracks.

Recommended PPE

As for PPE: I highly recommend wearing safety glasses and a filter mask. You really don’t want to risk globs of hot plastic flicking into your eyes accidentality. Especially since, if you are anything like me: chances are that your face is very close to the workpiece, in order to see every little detail. You also probably don’t want to suck up all those toxic fumes from any burning plastic either, so a cheap filter mask will help avoid that.

I would also recommend wearing a pair of thin rubber gloves. Although the plastic shouldn’t reach any serious temperatures before melting, a pair of gloves helps you comfortably shape any jellied plastic by hand; should you wish to do so.

Plastic welding techniques

I usually start by placing any loose container segments back into the gaps and holes that they broke out from. In a similar manner to welding metals, I then tack the loose segment into place. This is done by melting small spots across the circumferences of the segments; i.e. melting little bridges across the cracks. Do enough to keep each break out piece in place, or to stabilise a crack (in the case where there aren’t any breakout pieces, just cracks). For any holes where the original broken out piece has gone missing, you’ll have to use the sections of donor material to fill them in. I recommend melting the complete area into jelly, and shaping the mixed plastic mass into form. This is in order to properly blend the plastics into a watertight seal.

As an alternative to tack welds, some sticky tape can be used to hold a breakout piece in place while you weld. But this can get messy when you introduce heat near that tape. Depending on the type of tape you used, just some residual heat can cause the tape’s adhesive to turn into a sticky treacle that cakes the work area. The heat resistant kapton tape may be useful here, but it seems like a waste of resources using it for this application.

The general technique I employ in the actual repair, is by melting the donor strip onto the crack of the container. Then with the broadest side of the soldering gun’s tip, I scrap the extra material into the container’s crevasses. Like a plasterer covering a brick wall; pushing the plastic deep into it’s valleys. Then once one side is completed (exterior, interior), do the same for the other side of the fissure. That’s the short of it.

One thing to note however, this type of repair is not pretty. Although it can be very effective structurally. This is due to the repair involving melting and blending away the cracks. Then adding material to help remove any residual weak points. Weak points which tend to linger after a repair that doesn’t use any donor plastic.

The main reason for using donor plastic is because (in my opinion) plastic shrinks in the presence of heat. In other words, as you repair it with your soldering iron, the repaired plastic is actually smaller than what it was prior. This means that the repaired crack areas are actually thinner than they were originally. So consequently bolstering it with donor material is often necessary. Although admittedly it does make it look awful.

  • segment alignment
  • welding tacks
  • outer side done, inner side awaiting blending
  • inner side done
  • almost watertight after just initial fill and blend
  • container holds water well, despite drip leak

Demonstration of initial fix and seal

Closing thoughts

In summary plastic objects can be repaired should you wish to do so. It’ll require a soldering iron set to a low temperature and some donor plastic of the same type. Take care not to burn the plastic, and for goodness sake don’t breath the fumes in. Also remember that ideally any repaired food safe containers, should no longer be considered food safe. (However that could just be my general paranoia speaking.)

That’s all folks. Best of luck with your plastic welding adventures.

Thanks for reading.

#0014: Tip for reinserting self-tapping screws into plastic housings

Otto

#0014: Tip for reinserting self-tapping screws into plastic housings

What is a “self-tapping” screw?

Whenever one removes screws from a device – especially a mass produced consumer grade device with a plastic housing; then chances are that the screws that were removed were “self-tapping” screws. As the name suggests, these are screws that are designed to cut their thread into the inner diameter of the plastic hole of the device housing that they are inserted into at the factory.

All self tapping screws have a few distinct qualities in common. These include: a relatively deep thread in order to cut into and grip the plastic, and a wide pitch between these threads in order to more effectively slide into the material. Additionally most self tapping screws tend to come to a sharpened point in order to to aid in aligning the screw as it is inserted into the hole.

So what’s the actual tip?

Well, when reinserting a self-tapping screw into it’s plastic receptacle. It is good practice to initially rotate the screw counter-clockwise (loosen) until you feel it pop or click into place. This process aligns the screw with the pre-existing thread, and in doing so means that when the screw is screwed in, it will slide into the already established thread and not cut a new thread over or across the old one. When aligned correctly, the screw should screw into the hole with very little resistance.

Why use this method?

The reason why this is important, is because repeated re-boring of the plastic hole will eventually strip it out of any threading. This is because each time a new thread is cut into the plastics it removes material; which in turn incrementally widens the diameter of the hole in the process. This can continue to the point that it can no longer effectively hold the original screw within it. Avoiding re-tapping the thread every time you reinsert the screw will minimise your damage footprint when repairing/working on the same devices repeatedly. Which is always good.

Video demonstration

Please note: although it may look like I am using force to reinsert the screw, I am not. It’s just the awkward angle and set up that may make it appear that way.

What to do with an already stripped or overlarge hole?

There are a few remedies to take if this advice is coming to late. The quick and dirty solution is to use a larger size self tapping screw that then can cut a new thread into the widened hole. After which one has to then absolutely makes sure to always realign the new larger screw with it’s thread before reinserting it. This is because any further damage to the plastic hole may make it entirely unusable. E.g. a plastic stand-off splitting entirely due to it’s enlarged hole.

The more intensive repair requires filling the hole with something that the original sized screw can then bite into. The most likely materials used here are either hot glue for a “temporary” fix; or melted plastic of the same type as used by the device for a more permanent solution. If you use the melted plastic route: I recommend filling the hole entirely, then drilling a new hole of the correct diameter. Followed by finally using the original self tapping screw to cut a new thread into this virgin material.

#0013: Repair of a game controller with fatigued dome switches

Otto

#0013: Repair of a game controller with fatigued dome switches

What is a dome switch?

In order to know what dome switch fatigue is, we must first identify dome switches. Dome switches are buttons that utilise a dome made from silicon, rubber, polyurethane; or a similar material with the same elastic properties. This dome effectively acts like a spring and pushes the button back up when applied downward pressure is removed.

A typical dome switch will consist of several parts. These are: a (usually) plastic keypad key, an elastic dome, and a graphite pad. The switch key (or button) is mounted onto the elastic dome, additionally the graphite pad is attached to the concave or underside of this dome; and finally, this assembly is sat atop a patch of unconnected unmasked circuit board traces. These traces essentially function as switch terminals.

The idea is that when the downward force is applied to the key, the elastic dome is compressed; causing the graphite pad to press down on the unmasked PCB traces underneath it. This graphite pad actively bridges an electrical connection across these traces, due to graphite’s electrical conductivity.

When the connection is made across these traces, a logic level electric current (around 3.3 volts) is either pulled down to or pulled up from signal ground. It really depends on the IC (Integrated Circuit) chip that is managing and interpreting the keypad array as to the specifics. Anyway, the point is, essentially that is how the computer knows which buttons are pressed and for how long. After the pressing force is removed, the elasticity of the currently compressed dome material causes it to reset to it’s original domed profile. And in doing so it lifts the graphite pad from the traces and breaks the electrical connection.

Example of dome switches within a handset phone

Diagram of dome switch in action

image taken from: https://i.imgur.com/5K9Uy.gif

What is dome switch fatigue?

Dome switch fatigue, or more specifically dome fatigue: is when the domes within dome switches, develop a fault due to extended use that makes them no longer effectively reset their position. I.e. pop back up after they have been compressed.

The main symptom of dome fatigue is button sticking. In other words, when a button is pressed down, it either takes longer than it should to reset, or it stays down all together. This is assuming that the keypad is actually clean, as there are many reasons as to why a button might stick other than dome fatigue. Accumulated grease or oils, foreign objects (like food), and dust build up can easily cause button sticking.

Once the device has been opened, the domes themselves can be examined. Look for stress lines: thinner (often lighter) areas of material that can indicate structural weakness. I recommend comparing the suspect dome to it’s known good neighbours; adjacent domes from the same device that occupy buttons that don’t stick. Since they are from the same material stock and often from the same actual moulding as well (as is the case here), it can make spotting any actual stress signs easier. Common sense right?

As you can see in the example picture, there is a stress ring on the one of the four action button’s domes. This dome corresponds to the “A” button on an imitation USB Xbox 360 controller. Now I don’t mean to go on a tangent but I will say that imitation products like this controller are generally made to a price-point. I.e. the manufacturer cuts certain corners to bring the unit price down.

This is done in a bid to undercut the original product and sell itself as a budget alternative. In many cases the cut corners and lower quality product is mostly acceptable to the end user, as it is reflected in it’s price. However, these cuts tend to including: the sourcing of lower quality, less durable materials.

I believe this to be the issue here, although I haven’t had this controller for long. (Approximately a year.) I use this controller to mostly play platformers such as Splelunky. Since the “A” button is used to jump, it is by far the most used button; and it seems like over the time that I have owned it, I have just fatigued this particular dome. Either by some kind of repetitive flex damage (i.e. general use fatigue), or by just pressing too hard on it in moments of panic or frustration during play.

Example of “sticky button”

Example of fatigued dome

Repairing controllers with fatigued buttons

Sadly, an actual and effective repair of the dome itself is outside my capabilities. I just replaced the knackered dome with a fresh one. Well… a less knackered dome from a spares unit. As you can see I chose a third party “4 gamers” brand PlayStation2 controller as a donor unit. This is because that is all that I had on hand at the time. Additionally I am generally unwilling to purchase materials for a repair unless I have to. And to be honest, when it comes to repairing budget electronics such as this controller, it really is hard to justify spending any amount of money for materials, when one could spend a little more and purchase a new unit.

With this repair, I initially intended to replace the entire action button array (all four buttons), with domes from the spares unit. This is because the different types of domes will have different force pressure resistances, and bounce back elasticity. Which would lead to users experiencing different levels of tactile feedback or “button feel”.

At this level, I don’t mind much what the exact tactile feedback of the spares domes are; as I doubt specifying tactile feedback was much of a concern for this budget controller to begin with. Ergo this slapdash replacement wouldn’t necessarily denote a loss in overall device quality or user experience.

However I would mind if the feedback of the grouping of action buttons wasn’t uniform (or near enough). I.e. if one button was noticeably stiffer or mushier. That disparity in tactile feedback may actually become a distraction during play. It may even negatively affect a player’s performance; due to the player becoming accustomed to the tactile feedback of one button and then because of that either pressing to hard or not hard enough when they move onto another button (with a different level of resistance) in order to perform a different action. It may cause a misclick; either registering two inputs, if the new dome is significantly weaker/squishier or none at all if the new dome is significantly stiffer than the previous.

Unfortunately, I ended up just replacing the tired dome and using the rest of the three originals. Even though I have a picture of all four action button domes replaced on the controller. I dropped one on the floor shortly after that; and after 30 mins of searching. I just adapted to this strategy. In this case the new dome and the originals have similar (although not the same) level of tactile feedback to them. They aren’t different enough to be an issue. Not for me at least.

Spares unit

Application of spare dome(s)

Demonstration of device repair (before and after)

Original fatigued dome switch (green “A” button)

Although tactile feel can not be conveyed: notice the mushier, softer sound from the green “A” button when compared to the others.

Replaced dome switch (green “A” button)

The sound produced from the replaced dome is similar to the other three buttons, although they are not uniform themselves. There is an acceptable level of difference within tactile feedback across the buttons. The sound of the buttons when pressed reflects this.

Final thoughts

To sum up my basic ethos when it comes to repairing a device with fatigued domes. One, one has to replace the domes. As far as I can tell the domes themselves are irreparable. Two, When replacing the domes, it may be better to replace known good domes in a bid to get a uniformity of tactile feedback on all the buttons on a device, or at the very lest on a significant button grouping. Such as action buttons or directional (D-Pad) buttons. That’s the takeaway.

That’s all folks. Thanks for reading.

References, links, further reading

“Diagram of dome switch in action” gif taken from: https://i.imgur.com/5K9Uy.gif
https://www.mechanical-keyboard.org/advantages-and-disadvantages-of-mechanical-keyboards/
https://en.wikipedia.org/wiki/Keyboard_technology#Dome-switch_keyboard

#0008: Repair and Analysis of USB Micro type-B cables

Otto

#0008: Repair and Analysis of USB Micro type-B cables

picture of a dissected USB Micro B plug

If you are anything like me you probably have a sizeable collection of broken Micro USB cables neatly spooled onto a hook, or into a bag. Alternatively, you may even have them tangled into a rat king in a box or drawer somewhere … that is if you are a barbarian. You know who you are. So in an effort to lighten my ‘Spares & Repairs’ bin short of throwing things away (perish the thought!). I though it’d be good to repair a few. I know crazy right?

How and where do Micro USB cables typically break?

In order to repair something, we must first asses the damage. Where is it and how much is there? Well, with regards to the generic male USB 2.0 type-A plug to male USB Micro type-B plug cable: the damage is predominantly focused in the male Micro USB plug. Please note I will be using the term ‘Micro USB plug’ as shorthand for ‘male USB Micro type-B plug’ throughout this article.

picture of a bent USB Micro B plug

Initially, I used to get annoyed whenever a cable broke and rebuke the relatively delicate Micro USB plug as poorly designed. However, on reflection it is actually rather good that the weakest point in the pairing of the plug and socket: is in the plug and not the socket. Especially since after such incidents, the device socket tends to end up with little if no damage at all.

This is assuming that the majority of accidental breakages happen under certain conditions. These include: firstly, that the Micro USB plug is inserted into it’s respective socket on the device at the time. Whereupon it comes into acute mechanical stress by something akin a sudden impact (e.g. from a fall); or by a particularly vicious cable snag. This stress consequentially puts a lot of pressure on the connection between cable and device. Which in most cases causes the cable’s plug to give in before the device’s socket. Sometimes both are damaged if the impact is strong enough. However in a more typical scenario the plug breaks first, and in such a way as to leave the socket relatively unharmed.

Although my knee-jerk reaction is irritation whenever I perceive something as genuinely designed to break; I think in hindsight it is better that the cable’s plug is designed to break before the device’s socket. Since the cable is far easier (and consequently cheaper) to either replace or repair than the device would be. After doing some research, it seems that this is a conscious design decision (citation needed) and not one based on anti-consumer avarice, which (as a long time purchaser of consumer grade electronics) is the assumption that I have been conditioned to have in these types of scenarios. “Think Different”, Think Planned Obsolescence.

In this case, it is actually an iterative improvement on it’s predecessor: the Mini USB standard. Which suffered from port damage due to the shape and structural strength of the male plug, coupled with the fact that the retention and locking mechanism is located within the socket in the Mini USB standard. Whereas within the Micro USB standard, all such fragile and consequently breakable parts are located cable side. Having said that though, it still sucks when useful tools break so let’s try fixing them.

picture of a USB Mini socket. It shows the retention clips within the socket.
USB Mini socket

Structure of a male USB Micro type-B to male USB 2.0 type-A cable.

The male USB Micro type-B (or Micro USB) plug on average has typically four or five pads at it’s cable side and five interface pins that mate with it’s counterpart female socket. Please refer to the pin out diagram.

diagram depicting the wiring and pinout of a male USB 2.0 type-A to male USB Micro type B cable.

USB type-A:
Pin | Name | Wire Colour | Function
1 | VBUS | red | +5 volts supply
2 | D- | white | Data-
3 | D+ | green | Data+
4 | GND | black | Ground

USB Micro type-B:
Pin | Name | Wire Colour | Function
1 | VBUS | red | +5 volts supply
2 | D- | white | Data-
3 | D+ | green | Data+
4 | ID | no wire | ID pin for OTG functionality
5 | GND | black | Ground

Its simple really, pins 1 and 5 are used for power. Pin 1 supplies the +5 volts and pin 5 is it’s ground. Pins 2 and 3 are used for transmitting the data signals for communication. And finally, pin 4 is an identification pin, which is used for USB ‘On The Go’ functionality. It essentially tells the device that it is connected to, whether or not it is to act as a host system or a slave device when communicating with the device on the other end of the cable.

hyperlink: post_#0009:_Brief_guide_to_creating_a_USB_OTG_cable

Its a very similar setup with the male USB 2.0 type-A plug on the other side of this cable, except that it lacks an ID pin. Pin 1 is the V bus carrying +5 volts, pin 4 is the signal ground, and pins 2 and 3 are the negative and positive data pins respectively.

The reason the USB type-A plug lacks an ID pin is because any device that has a full sized female USB type-A port is already assumed to be the host system. Finding a peripheral device such as a keyboard (with the exception of USB pass-through), or mouse, or even a smart phone with a full sized female USB type-A socket is non-standard; as are the male USB type-A to male USB type-A cables needed for them.

The wikipedia.org article (“USB hardware”) mentioning this cable labels it as ‘proprietary, hazardous’. If I were to guess as to why that is, I’d say its because it allows the connection of two host systems (e.g. 2 personal computers), with no protocol to decide the role either system has to play. Additionally the input of power into a host system via it’s USB ports may cause damage (e.g. to it’s USB controller) because it may lack short circuit or input protection.

The Repair

Now that we have a basic understanding of the structure of the Micro USB plug and where the damage typically is. We can proceed to repair one.

Recommended tooling:

  • soldering iron
  • hot air station / heat-gun / lighter
  • hot-glue gun
  • precision knife
  • third hand clamps (handy grips, etc.)
  • testing adapters
  • female USB type-A socket breakout board
  • female micro USB type-B socket breakout board
  • multimeter
  • pliers

Consumables:

  • hot-glue
  • heat-shrink
  • Micro USB male plug kit
  • (lead-free or leaded) solder
  • rosin flux
  • electrical tape

P.P.E.:

  • safety glasses
  • light heat resistant gloves

The list above is just as a guide the the types of tools and consumables that you may need. Most of them are optional and are subject to personal preferences and circumstance.

Methods of repairing items

Most real world cable repairs I think broadly fall into one of the three categories or ‘methods’ I outline below. They all have advantages and disadvantages. Some allow for saving more time than money and other’s vice versa. Which ones are most appropriate to use will predominantly be based on the repair technician’s personal preference, available materials, and circumstances.

For example one could if one had two good candidate cables, splice them together into a working unit (i.e. method #1) using minimal tooling: just a knife to strip the wires, several unsoldered pig tail splices for the connections, and some electrical tape to isolate the USB wires from each other. And it would work fine. How long for? Who knows – but it will work for the moment and that may actually be enough. I give the example just to illustrate that things can be repaired a number of ways depending on either the person’s (in this case low) resources, and preferences; which can the run the gambit from the “just get it working for now” repair (shown above), to the perfectionist who wants a permanent repair that will outlast the product.

Method #1: splice two cables together

Probably the quickest method of repair involves simply splicing together two cables. This involves cutting the damaged parts off, then joining and soldering the four pairs of wires together according to their colouring. Red and red, green and green, white and white, black and black; and even sometimes the foil metal shielding if present. Simple. However, be mindful to first electrically isolate each of the four individual pairs, then cover over with a larger gauge heat shrink (for neatness) or electrical tape (for cheapness) to group everything together. I recommend a soldered Western Union splice as a method of joining the wires in the pairings. This is due to it’s relatively low profile and due to the mechanical strength of the resulting connection. Which means that in the case of any future tension on the cable such a sudden hard snag; chances are good that the new connection will not break. Nothing hurts my pride quite like having to repair one of my prior repairs. Consequently, I tend to do it properly the first time round.

hyperlink: post_#0003_Basic_techniques_for_connecting_wires

Now, there are obvious limitations to this method. The most pressing is that cables tend to get damaged in the same spot as each other. Especially when used in the same environment (or by the same people!), and in the same applications. So this method is not applicable in these cases. However in cases where it is applicable it is the shortest and easiest route to creating a reliable and viable cable. Primarily because it effectively bypasses the often finicky business of repairing the actual Micro USB plug.

Method #2: mend and make do (with salvaged spares)

So, like I mentioned above: most of these cables break at the same point. Namely, the male Micro USB plug. So unless you want to end up with a bunch of double ended (full size) male USB type-A cables. Splicing together the good ends of your broken cables isn’t going to do you much good.

So what now? Well first things first. We need to understand the extent of the damage itself. When you examine a broken Micro USB plug. If the metal outer shielding of the plug is present, then chances are that the metal plug itself is bent out of alignment by a fair few degrees across it’s broader sides. In this configuration, the state of the plug’s internal pins is unknown; or more to the point: it is unknown as to whether there is continuity across the pins (i.e. are they snapped or broken). By using a pair of pliers you can carefully correct the angle of the plug. I recommend doing this slowly before trying any other fixes. It needs to be slow, in order to give the delicate internal pins time to bend back into alignment. If the cable works after this, then that means that the internal pins were merely bent and not broken; and it also means that the repair is effectively done.

Alternatively, if after angle correction there is no continuity across the cable. Either by buzzing it out using various adapters and a multimeter — or just by plugging it into (hopefully inexpensive) devices and seeing if the devices recognise each other. Then it is time for a more invasive solution. I stipulate ‘inexpensive’ because many devices with USB ports don’t have adequate protection in cases of hard shorts to ground. It’d be pretty disheartening if a person, for example killed that USB 3.0 port on a their wiz bang gaming rig, because the wires were accidentally soldered incorrectly or shorted on that cheap shit cable they were trying to mend. I doubt that would actually happen, but better safe than sorry.

With a sharp knife, slice into the rubber or plastic sides of the plug. Create a broad slice from where the metal Micro USB plug’s base is (or was), all the way across the plug housing and up close to the strain relief. Peel back the rubber or carefully pry open the plastic to reveal the base of the Micro USB plug. Here you should be able to see where the four wires (for a data cable) or two wires (for a power cable) connect to the Micro USB plug’s base internal section.

This area of the cable: where cable meets Micro USB plug; tends to be either injection moulded with plastic or rubber, or filled with a type of hot glue. It is very easy to do more damage to the plug trying to get to it, then the damage that caused the cable to become inoperable in the first place. So if you intend to repair the Micro USB plug (rather than replace it), I advise proceeding with caution here.

Once you have made it to the base of the Micro USB plug. You many notice that the metal outer shield of the Micro USB is sometimes removable. If yours is, then it should be held in by a clip of some sort. Unclip it. Continue carefully dissembling the plug until you find the fault. In my case the internal pins broke as the plug was bent. I could try to re-solder them together or I could replace the Micro USB base with one from either another plug or a spares kit. Since this is the ‘mend and make do’ method, let’s say I went through the tedium of realigning the tiny pins and soldering them – and without melting their plastic housing or shorting them together no less … What I actually did was just replace the plug base with a known good one, for time and reliability.

Reassemble the plug. Then fill in any cavities you may have carved out on your way in, with hot glue. Close the cable head up, then wrap it in electrical tape. Done.

The strength of this method is that you can repair the cable without necessarily having to purchase additional parts. However the disadvantages are that it is very time consuming and finicky work. Work that could ultimately leave you with a plug that is structurally even weaker than the one you started with. So it may soon break again if not handled with care going forwards.

Make sure to do a through continuity test before pressing this cable back into service. Especially when it comes to testing for shorts across the pins. This includes pin 4, which depending on the testing adapter socket you are using, might be inaccessible. In this case I used to use crocodile-clip leads and needles as probes to test the pins on the exposed male plug without a female adapter. Although, I actually recommend just purchasing (or creating) a female Micro USB socket breakout board. It makes life so much easier than faffing about with a bunch of random low quality adapters or needles … which is what I used to do, and don’t really recommend. But sometimes you have to just use the tools in front of you.

  • picture of a dissected USB Micro B plug

Method #3: use a spares kit

This is probably the simplest actual repair after splicing two appropriate cables together. This method involves using a kit to replace the entire Micro USB plug assembly, including the strain relief. After cutting off and discarding the Micro USB head, remove the outer insulation of the cable, strip the the USB wires within and tin them. If the outer insulation is a fabric braid type, then melt the tip of the insulation with heat to stop it from unravelling.

  • picture of a bag of USB Micro B plug heads
  • picture of a USB Micro B plug in parts

Next up, slide on heat shrink (for cable bend relief), and then the Micro USB plug housing. This stage is probably easiest to forget. I can’t count the number of times, I have made a really nice soldered connection, only to undo it because I didn’t remember to slide on heat shrink beforehand. It’s funny, it only really happens on the more permanent joints, like the Western Union splice. I think its because I tend to be too preoccupied with making a good strong connection, that consequently: these types of things tend to slip my mind at the time. So take your time and do things methodically.

Just as an aside: heat shrink, in my opinion makes a good form of bend relief for a cable because it makes the cable a little stiffer along the length leading into the plug. This gives it resistance to bending to extreme angles, or allowing repetitive bend or flex damage to concentrate on a singular point on the cable. As for strain relief for the solder joints on the plug base: adding heat shrink to the cable does little. Id est it doesn’t prevent tugging force on the cable from exerting strain on the soldered connections between the cable’s wires and the Micro USB base’s pads. I’d carefully tie the cable end into a loose overhand knot (if it is of a thin enough gauge to do this), making sure not to cause any acute stress points in the wires as a result. This knot will act as a stopper against the insides of the Micro USB plug’s plastic housing. I am not sure whether or not this is generally advisable protocol, I am just stating what I tend to do. The loose knot offers some resistance to a tugging force as it tightens against the hole in the plastic housing. This in turn relieves the solder joints of some of the strain. Alternatively, filling the Micro USB plug’s housing with hot glue will also act as a decent form of (tugging) strain relief for the solder joints. These two methods do this by redirecting the pulling force away from the solder joints and into the housing and general superstructure of the plug.

Moving on. Now with everything in place, solder the USB wires to their respective pads on the Micro USB plug base. This includes the cable’s outer conductive shielding if present. In order to know which pads correspond to which pins: refer to any user guides or datasheets that may have been shipped with your spares kit. Alternatively test the continuity of the pads to the pins using a multimeter and a female Micro USB breakout board.

To connect the cable’s shielding: roll the loose strands into a cord. You may need to wrap this cord with another wire to extend it enough to reach the Micro USB plug’s outer metal housing. Which is a little further away than the USB solder pads on the example kit I have. I needed this extension to the shielding cord because when I cut the cable, it made all the internal wires and strands equal in length, so an extension was necessary in my case. After scratching off the finish on the part of the Micro USB plug’s metal housing that you intend to solder onto. Apply a small patch of electrical tape to insulate the USB wires from the shielding connection. Next, solder the shielding cord to the metal housing. You may need to apply solder to the twisted shielding cord to harden it and fuse the extension if necessary.

Now. Isolate the internal USB wires from each other, by injecting hot glue over and between the four wires. I use the electrical tape from before as a backing for this. I chose to have the adhesive side facing the USB wires, because I intended to wrap it around them at this stage. After this, pull the heat shrink into position then apply heat. Pull the plastic housing over the plug base and align the plug so that it is straight. I used the plastic cap to set the plug’s position. Once satisfied with the plug’s position within it’s plastic enclosure; remove the plastic alignment cap again and inject hot glue to fill any cavities between the plug base and the enclosure. Reapply the alignment cap. Then carefully apply some heat to the now closed plastic housing to make the hot glue within the enclosure melt into all the crevices and hold the alignment cap on. Be careful here because using too much heat can easily damage the plastic enclosure and alignment cap. Once that is done you are effectively finished.

  • picture of a USB 2.0 type A to USB Micro type B cable. The USB Micro B cable has been replaced with a plug kit.

Testing Phase

Although I tend to test at each discrete stage of a repair, for things such as bridged connections between pins or for consistent continuity across connections. I also recommend a final testing phase where we test the resistance of each wire using a USB 2.0 type-A female breakout board and a USB Micro type-B breakout board; or whatever the appropriate boards for the cable you are testing are.

The reason why I do this is to make sure that all the lines are of appropriate conductivity. In other words there aren’t any spikes in resistance in any of the lines that may cause problems when in use. This is especially true for data lines, where resistance will damage signal integrity. Although it is also important for power lines in use-cases involving higher current draws (around 2-3 Amps), such as those used in ‘fast chargers’. If there is sufficient resistance on the VBUS here it will retard the device’s ability to draw power across the cable.

Examples of improvised testing adapters

picture of a partially repaired USB cable inserted into some adapters for testing.
picture of 2 USB type A plugs. One has been stripped of insulation to be used for testing.

It’s generally good protocol to have a control test for comparison when testing your repaired cable(s). In this case I used a Samsung brand, model: U2 APCBU10BBE data cable that came new with a smart phone purchase. Please note: the control cable used here is not designed for higher current draws, it’s device needed a maximum of around 700mA to 1 amp when charging.

(Control) Samsung (U2 APCBU10BBE) data cable:
VBUS: 0.2 ohms
D-: 0.3 ohms
D+: 0.3 ohms
GND: 0.4 ohms
Shielding: none
Cable length (approx.): 1 meter

(Testing) Repaired w/kit yellow cable:
VBUS: 0.2 ohms
D-: 0.3 ohms
D+: 0.5 ohms
GND: 0.6 ohms
Shielding: 0.1 ohms
Cable length (approx.): 1 meter

(Testing) Repaired w/spares red braid (‘fast charge’) cable:
VBUS: 0.2 ohms
D-: 0.3 ohms
D+: 0.2 ohms
GND: 0.1 ohms
Shielding: none
Cable length (approx.): 2 meters

picture of a new USB 2.0 type A to USB Micro type B cable, connected to some breakout boards used for testing. This cable was used as a Control test.
picture of a spares repaired USB 2.0 type A to USB Micro type B cable, connected to some breakout boards used for testing.
picture of a spares repaired USB 2.0 type A to USB Micro type B cable, connected to some breakout boards used for testing.
picture of the USB type A female socket breakout board and USB Micro B female socket breakout board used for testing.
picture of a kit repaired USB 2.0 type A to USB Micro type B cable, connected to some breakout boards used for testing.

As you can see, they tested close enough that I feel that the cables that we repaired are of an appropriate quality, at least for me to have enough confidence to press them into service. Alternatively instead of using a control test for comparison, if you manage to find a datasheet for a particular cable you wish to replicate. The data from the datasheet can be used as a target instead. I just found it easier to see how my everyday cable fairs, then try to ape it’s stats. Consequently I do not have a concrete idea of what the resistance tolerances and acceptable margins are for these cables to maintain signal integrity while in use. But I am confident from the comparisons with the control cable that we are within them.

However, if say a cable tested (pulling numbers from my … hat) 15 ohms on a data line. I would inspect the repair, if it seems fine: then the problem could be with the cable itself. For example: such as in a wire where many of it’s hidden internal strands have broken due to repeated localised flex damage. So all the current is having to pass through just a few strands at that point, causing an invisible bottleneck. This should have been tested for at the initial stages of a repair when the cable was first cut and the wires exposed. But still, finding this fault at this stage, allows you to make the informed decision on how to go forwards, either demote it to a power only cable (and mark it as such), scrap it for parts, or find and fix the newly discovered fault.

Eventually, once you reach a stage where you are confident in a cable’s performance, the repair is truly complete and it is now ready to use. Done. This time for real. Thank you for reading.

References / Sources / Further Reading:

https://en.wikibooks.org/wiki/Serial_Programming/USB#What_is_USB?
https://en.wikipedia.org/wiki/USB
https://en.wikipedia.org/wiki/USB_hardware
https://en.wikipedia.org/wiki/USB_On-The-Go
https://en.wikipedia.org/wiki/USB_(Communications)#Signaling_state
https://www.ifixit.com/Guide/Micro-USB+Port+Replacement/73401
https://www.portplugs.com/how-to-repair-a-loose-micro-usb-port/
https://www.youtube.com/watch?v=36CKsP9YQ1E [why does USB keep changing – NostalgiaNerd]
https://goughlui.com/2014/10/01/usb-cable-resistance-why-your-phonetablet-might-be-charging-slow/
https://www.mschoeffler.de/2017/10/29/tutorial-how-to-repair-broken-usb-cables-micro-usb-including-data-transfer/
https://www.mouser.com/pdfdocs/HiroseZX62Datasheet24200011.pdf
https://www.howtogeek.com/670644/what-is-fast-charging-and-how-does-it-work/

#0007: Restoring metal tools

Otto

#0007: Restoring metal tools

side by side picture of a pair of mini-nippers before and after cleaning.

A little while ago I received a bunch of tools for free from a friend, due to them downsizing their home. Unfortunately these tools were stored improperly and suffered weathering damage as a result. They were essentially stored in a puddle, in a bucket, in a leaky shed. Basically leaving everything rusted to one degree or another.

I took the loot home and sorted the good from the bad. And just as I was about to discard the rest; the sheer volume of rusty crap gave me pause. I wondered as to how much of it I could actually save and refurbish to a useable state. However, I should also mention that I was largely unwilling to actually spend any money on this project. I wanted to see what I could do with the tools and resources I have on hand. Consequently I used household sundries like vinegar instead of a rust remover product, and would’ve used some-kind of random household oil (such as cooking oil or bicycle lubricant) instead of WD40 to loosen any seized tools if I didn’t already have it to hand.

example of rust remover product
picture of 5 litre jug of evaporust branded rust remover product

Okay, let jump in. These are the tools and materials I used:

Tools:
    - plastic container
    - wire brush
    - (ball point) hammer
Consumables:
    - water
    - vinegar
    - WD40
PPE:
    - safety glasses
    - thick gloves
    - apron

It’s a nice small list. So there is little in the way of barriers to entry. Meaning that the strength of this method is that it allows people with very limited resources to simply add salvaged tools to their resource pool whenever they find them, and consequently increase their effectiveness.

picture depicting a collection of tools. A wire brush, a spray can of WD40, and a pair of thick gloves.
picture depicting a blue plastic tub and a bottle of inexpensive vinegar.

Basic Method:

I created an acid bath by mixing water and vinegar in a 1:1 ratio into a (barely) large enough container. Added the tools and waited a couple of days (7+) for the acid to fully react with the rust until the solution formed a thick brown foam on it’s surface. Then removed the items from the bath and scrubbed them down with the wire brush until all traces of rust has been removed.

After which, I finished each item off by it wiping dry with a rag. Then wetting it with another rag laced with WD40, and working the solution into the tools’ various crevices to help expunge any traces of moisture and to provide some protection against any further corrosion.

  • picture depicting an acid bath with tools submerged within it. A large amount of caramel coloured foam has formed on the solution's surface.
  • picture depicting the plastic acid bath tub after the submerged tools have bben removed from it.
  • picture depicting a rusted pair of garden shears with it's blades half covered in the caramel coloured foam from the vinegar bath.

Notable specifics:

Acid Bath:

The reason why I use an acid bath is to react with and consequently remove the the rust. Rust is a form of iron-oxide compound; the acid reacts with the oxygen in the compound and breaks it as a result. Any residual rust left over after the submerging period will in all likelihood be structurally compromised (softened up) and consequently easier to remove manually with a wire brush.

The reason why I use vinegar is because: one; as mentioned above, I didn’t want to spend money and vinegar was a readily available household sundry; and two, vinegar is a very weak (and consequently safe) acid that will return good results if left to work for a long enough time period. I submerged the tools in it for more than a week before I worked on them. Had I used a stronger acid (such as phosphoric acid) or a product (such as evaporust) I would’ve been done within the day and would not in all probability have to work on the tools with a wire brush.

However by successfully using vinegar, it illustrates that it can be done at little cost. Funnily enough it also adheres to that old adage “you can have it done fast and cheaply, but not good; cheap and good, but not fast; or good and fast, but not cheap.” Vinegar would be the second option in that adage.

Additionally, vinegar is such a weak acid that the chances of it damaging the good metal underneath the rust is said to be minimal. Hence less care and attention is needed with it’s application. However having said that, it seems that vinegar does indeed remove material from the tools (as can be seen within the photograph of the partially dipped shears). Whether or not it started to eat away at ‘healthy’ metal or simply removed a thick layer of rust (including the patina) is hard to tell. What I can say definitively is that more material is lost from the tool in the process of using an acid bath over just scrubbing with a wire-brush.

As a final note on this, a good way to immerse items that are perhaps a little too big for the tub you have on hand; is by using rags to wet the areas of tools that are above the waterline. You don’t even have to dip the area below the water level. As long as the rag touches the solution; the capillary effect of the cloth will draw up the liquid towards the areas of the metal that you have wrapped the rag around. Using wet rags is also a good way to avoid a case that requires using voluminous amounts of solution to fill up a big enough container to submerge large or awkwardly shaped items.

example of rags used in an acid bath
  • picture depicting a screwdriver and a large drill bit wrapped in rags.
  • picture depicting a rag wrapped metal tool in an acid bath. The rag is wicking the vinegar up and around the parts of the tool that are above the water level.
  • picture depicting a rag wrapped metal tool in an acid bath. The rag is wicking the vinegar up and around the parts of the tool that are above the water level.
  • picture depicting a rag wrapped metal tool in an acid bath. The rag is wicking the vinegar up and around the parts of the tool that are above the water level.
  • picture depicting a rag wrapped metal tool in an acid bath. The rag is wicking the vinegar up and around the parts of the tool that are above the water level.
  • picture depicting an acid bath with tools submerged within it. A caramel coloured foam has formed on the solution's surface.
screwdriver before and after
  • picture depicting a flat head screwdriver pitted with surface rust
  • picture depicting a flat head screwdriver pitted with surface rust (close up on the rust)
  • picture depicting a flat head screwdriver's shiny yet pitted metal finish after a clean
  • picture depicting a flat head screwdriver's shiny yet pitted metal finish after a clean (close up)
  • picture depicting a flat head screwdriver's shiny yet pitted metal finish after a clean (close up)
comparison between bathed and scrubbed metal and just scrubbed metal
  • picture depicting a rusted pair of garden shears with it's blades half covered in the caramel coloured foam from the vinegar bath.
  • picture depicting a garden shear the has been partially cleaned. The shear's blades have been cleaned and brushed only halfway to illustrate the difference between clean and rusted.
  • picture depicting a medium close up of a garden shear's blade that has been partially cleaned. The shear's blades have been cleaned and brushed only halfway to illustrate the difference between clean and rusted.
  • picture depicting a close up of a garden shear's blade that has been partially cleaned. The shear's blades have been cleaned and brushed only halfway to illustrate the difference between clean and rusted.
  • picture depicting a very close up of a garden shear's blade that has been partially cleaned. The shear's blades have been cleaned and brushed only halfway to illustrate the difference between clean and rusted. Two layers of metal removed can be seen.

Mini end nippers:

Anything with a seized mechanism such as the pictured mini end-nippers; required WD40 to be applied and allowed to soak into the joints of the mechanism. After allowing it to soak in, I worked the handles again and again until the joints started moving. I continued this until the rust inside the mechanism was macerated by the WD40, and worked out by the repeating opening and closing of the joint.

A hammer might be needed to apply sudden force to either the tool’s (let’s say pliers) jaws, handle, or the joint mechanism itself to loosen it up in the case of a strong seizure. I used a ball point hammer to help localise the hit just to the specific joint without pointlessly impacting the frame of the tool. A hammer punch will also be very effective in directing and localising applied force. Sharpening the nipper’s jaws with a file is also recommended as a final touch.

washed and scrubbed but mechanism still seized
  • picture depicting a close up on a rusted pair of mini end nippers
  • picture depicting a rusted pair of mini end nippers inhand
  • picture depicting a rusted pair of mini end nippers covered in the caramel coloured foam from the vinegar bath
  • picture depicting a close up of a rusted pair of mini end nippers covered in the caramel coloured foam from the vinegar bath
  • picture depicting a close up on a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism looks seized closed.
  • picture depicting a close up on a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism looks seized closed.
  • picture depicting a close up on a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism looks seized closed.
mechanism lubricated and made operable
  • picture depicting a disassembled and partially cleaned pair of mini end nippers
  • picture depicting a partially assembled clean pair of mini end nippers
  • picture depicting a pair of mini end nippers with a ball point hammer next to it
  • picture depicting a close up on the mechanism of the mini end nippers. A lot of debris wet with WD40 has been worked out of it.
  • picture depicting a close up on the underside of the mechanism of the mini end nippers. A lot of debris wet with WD40 has been worked out of it.
  • picture depicting a close up on the underside of a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism looks loose and functional.
  • picture depicting a close up on a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism is loose and functional.
  • picture depicting a close up on a cleaned pair of mini end nippers, its very pitted yet shiny. The jaw mechanism is loose and functional.
  • picture depicting a cleaned and assembled pair of mini end nippers

Drill bits:

With these I found that holding the brush in the left hand and scrubbing with (i.e. in the same direction as) the thread is the best way to get deep into the bits valleys and remove the rust as efficiently as possible. After the bits are cleaned, they also need to be sharpened with either a small file or some kind of specialised bit sharpener.

complete before and after comparison
  • picture depicting a collection of drill bits for comparison. Half of them are fully cleaned and brushed and the other half are in their original rusted condition.
  • picture depicting a close up on a collection of drill bits for comparison. Half of them are fully cleaned and brushed and the other half are in their original rusted condition.
drill bits after acid bath, before scrubbing and oiling
  • picture depicting a collection of drill bits post acid bath but prior to wire brushing.
  • picture depicting a close up on a collection of drill bits post acid bath but prior to wire brushing.
after scrubbing and oiling
  • picture depicting a close up on a collection of cleaned and oiled drill bits.
  • picture depicting a collection of cleaned and oiled drill bits.
  • picture depicting a collection of cleaned and oiled drill bits.

Personal Protective Equipment:

This is something that is often overlooked by people, however I do think that personal safety is something that people should take into account on any and all projects. Well, as long as you don’t go overboard to the point of the sometimes overbearing British “Elf and Safety” silliness. I have seen people on job-sites with overbearing rules go the complete opposite direction as a form of rebellion as soon as the manager is out of sight. Discarding basic things like gloves and eyewear in the process. Its sad honestly.

I am getting off topic. In this case, the apron keeps the rust vinegar mix off of your clothes as you brush down the items (if you care); and more importantly the safety glasses keep that stuff from flicking into you eyes in a moment of inattention. That’s probably the main reason why I wear these things for everything from soldering to this. Its because I am aware that my attention ebbs and flows as I perform tasks, I am not always in the moment 100% and that’s when accidents happen.

So for me at least. Safety glasses are a must, I don’t want to take any chances with my sight. However everything else is largely optional. I also added gloves to protect the hand that is holding down the workpiece from the wire brush. I put these on to allow me to work quickly and effectively.

The point is, there needs to be a mindful reason as to why and when (and when not) to use PPE in projects, even mundane ones such as this.

References, Sources, Further reading:

https://en.wikipedia.org/wiki/Iron_oxide
https://en.wikipedia.org/wiki/Rust
https://en.wikipedia.org/wiki/Patina
Geoffrey Croker – Rust Removal Methods Explained [https://www.youtube.com/watch?v=Qi-tK1jwO-k]
Slavscribe – How to remove rust? Acid vs. Bolt | AcidTube-Chemical reactions [https://www.youtube.com/watch?v=k9OYNPCnLNs]