#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 Which in turn allowed the blade tip to scratch the handle as it was retracted into it.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