Modifying EDC Folders

J

jencarlos

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Hey, guys. This is my first post in a while. I'm glad to be back! I'm in the process (disassembly stage) of doing some minor modifications to two of the folders I carry. Both are old-school Japanese Cold Steel (Scimitar and Custom Series Black Talon). This is my first time doing anything to a folder, so I'm not going to go too crazy. It will probably be limited to phosphorous bronze washers (to replace the plastic ones) and new screws. The washers are really easy but I'm having trouble with the screws and I was wondering if any of you could be of help.

1. Screw sizes: I'm not well-versed in this area and I don't really know how to look for screws by size. I'd assume knife screws mostly come in standardized sizes to keep things simple in the industry, but I have no clue if mine are metric or imperial. Does it matter? Will measuring them with a caliper tell me what I need to know?

2. Screw types: I'd like to change all of the screws to Torx Plus, but I haven't been able to find any. Does anyone know a place? I'll settle for regular Torx if Torx Plus is unavailable. Also, I'd like to increase the bit size either way. The Black Talon currently uses T6 for the scales and T10 for the main pivot. I'm fine with the main pivot (though I'd prefer T15 or T20), but I'd really like to upgrade the scale screws to T8 over T6. I just don't know if it's possible. That's what started all of this anyway (long story short, a T6 came loose in the Black Talon and driving it back in stripped it). The Scimitar uses hex (I found a spare Allen key that fits the scale screws perfectly but I have no clue what size it actually is). The main pivot was undone with a 2.5mm hex.

3. Thumb stud: The Scimitar has an ambidextrous volcano thumb stud. It's slotted on one end. I tried turning it but I couldn't get it to move (Loctite probably?). I'll hit it with a hairdryer and try again. The goal is to change to a right-hand only stud that's more cylindrical. If anyone has any other ideas for removal in the meantime, I'd definitely appreciate it.

4. Final concerns: On both knives, there is a metal washer that sits between the scale/bolster and the screw of the main pivot. Is this a necessary piece? How so?

Sorry for the long read and thanks in advance!
 
Just an update. I removed the thumb stud on the Scimitar with no problems. The hairdryer did the trick.
 
Knives made in Asian countries, even ones made for American companies for sale in the US, tend to use metric screws. And yes, it does matter which ones you use, although 2.5mm screws (metric) and 3-56 screws (SAE) are virtually identical and interchangeable (I'm using 3-56 screws in place of 2.5mm handle screws in some of my customized Cold Steel Ti-lites). But I believe that is the only SAE/metric crossover, so don't expect to be able to replace other metric screws with SAE.

My advice is to buy a screw sizer. It's just a plate of metal or plastic with threaded holes that you can use to determine the types and sizes of screws.

Or, you can take the screws to a hardware store, they tend to have screw sizers in their fastener departments, but their screw sizers don't always go down to really small screw sizes like knife handle screws.

As far as trying to find larger torx sizes and switching to torx plus, when you figure out the correct screw sizes check McMaster-Carr.com, they sell a wide variety of screws, but you might have to purchase them in larger numbers than you need, they rarely sell individual screws.

EDIT- I just checked, and McMaster-carr has a large selection of stainless steel metric screw sizes with torx plus drives.
 
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Thanks K killgar I'll get a sizer. I'm on McMaster's website right now looking at screws. Each one has a dimension given that I can only assume is the length of the screw. Do you know if that refers to the overall length or just the length of the shaft?
 
jencarlos said:
Thanks K killgar I'll get a sizer. I'm on McMaster's website right now looking at screws. Each one has a dimension given that I can only assume is the length of the screw. Do you know if that refers to the overall length or just the length of the shaft?
Click to expand...

You're welcome.

When McMaster refers to "length" in their description of a screw, they are referring to the threaded portion of the screw, or "shaft" as you say (of course some screws are only partially threaded, but again, their use of the word "length" refers to the entire shaft, threaded or unthreaded).

In the description of the screw there is a separate column/description for the height of the screw head (as well as the diameter of the screw head).

And if you click on a specific items part number (blue numbers), then click "Product Detail" (also in blue, lower left corner of the pop-up box), they provide a detailed schematic of the item with all dimensions listed.
 
Since I don't have a sizer at the moment, I made all of the other measurements of my Scimitar screws using a caliper.

Scale Screws (5)
(ALL) 2.2 mm Shaft Thickness
(ALL) 4.3 mm Head Width
(2x) 8.9 mm OAL
(2x) 6.9 mm OAL
(1x) 4.9 mm OAL
The differing OAL values are due to handle taper.
(ALL) ~2 mm Head Height (as a portion of OAL, hard to measure)

Main Pivot Screw (1)
4.9 mm Shaft Thickness
7.5 mm Head Width
6.1 mm OAL
~2 mm Head Height (as a portion of OAL, hard to measure)

Are those values useful for determining whether I'm dealing with metric/imperial screws, or does the metric/imperial distinction only apply to the thread pitch?
 
For metric screws, all measurements, including thread pitch, are metric. For example- the handle screws on the Cold Steel Ti-lite 6 are M2.5 X 0.45. "M" stands for major nominal diameter, 2.5 is the width of the threaded shaft in millimeters, and 0.45 is the thread pitch in millimeters (as opposed to SAE thread count- threads per inch). A thread pitch of 0.45mm means there is 0.45 millimeters of space between threads. The pivot screw of the Ti-Lite 6 is M4 X 0.70. But of course Cold Steel uses different size screws for different knives. Based on your measurements I'd wager the screws you described are M2.5, (2.5mm, handle), and M5, (5mm, pivot).

The problem with trying to size screws with calipers are- if the calipers are the slightest bit off, you'll get an odd measurement. Also, screws are mass-produced, so there can be slight variations in size from one run to another that can affect a caliper reading. Also, once a screw has been used the threads can get slightly flattened/deformed, which can affect a measurement. The screws used for knives are very inexpensive, and as such, they aren't made to a high degree of consistent precision, it's not like they're made for NASA.

The best way to size screws is to use a quality screw sizer, or test with screws that you already know the sizes of. Commercial grade screw sizers aren't NASA grade precision either, but when you try to thread a screw into a series of threaded holes, and the screw threads into one of the holes but not any others, then you'll have a good idea what size it is.
 
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K killgar thanks again for all of your help. I really appreciate it! I ordered a screw sizer online but I'm still going to take a trip back to the hardware store to see if they have any I can use there. I only have one piece of the puzzle left. Do you (or anyone else so I'm not just bothering you :D) know the purpose of that little washer that sits between the head of the main pivot screw and the countersink of the bolster (in the Black Talon) and the scale (in the Scimitar)? If it's a necessary component, is there any upgrade there that's possible? I wouldn't think so, but I figured I'd ask while I still have the knives disassembled all the way.
 
You're not bothering me . I like to help where I can :).

I don't know the inner workings of those two knives, but I'd say it's a safe bet that if Cold Steel put those washers in there, and spent money to put them in there, then they need to be there.

On a different topic- in regards to the internal pivot washers, finding bronze phosphor washers that are an exact match to Cold Steel washers can be difficult to impossible. Once again, the diameter of the pivot barrel will be metric, and aftermarket BP washers tend to be made with SAE measurements. The washers used in Cold Steel knives are likely made specifically for them.

To use the Ti-lite 6 again as an example, the stock washers do not match any of the aftermarket washers I have ever purchased, and I keep a wide variety on hand for knifemaking (a pic of my assortment below). In the past, when I wanted to change or add an aftermarket BP washer in a Ti-lite, I had to either go with a larger size, or customize a smaller size (like enlarging the hole with a very fine round file).

And then there is the thickness of the washers. They come in a variety of thicknesses, and you'll need the correct thickness. It can be tricky to determine the exact thickness, so once you figure out the outer and inner diameter washers you need, you might want to purchase a few different thicknesses so you can test until you figure out the best fit (one reason why I keep such a large assortment). Fortunately BP washers are not expensive.

And now a word about washer material-

I'll start with a little story- Quite awhile back I decided to replace the white Teflon washers in a Ti-Lite 4 with bronze phosphor washers, believing the BP washers were superior. With the Teflon washers in the knife it opened easily with a flick of my wrist. But with the BP washers it didn't. The BP washers never produced the same slick opening as the Teflon, so I switched back.

I did some research to try and understand this, and as it turns out, the coefficient of friction, or COF (how slipperiness of material is measured) of bronze phosphor is 0.35, but the COF of Teflon is between 0.05 and 0.20. In other words, Teflon is more slippery.

So why do many knifemakers use bronze phosphor washers? Perhaps because they are more durable that Teflon, and will last longer (wear) with less chance of deformation if the knife is used in a stressful manner. But many others use Teflon or Nylatron.

My point is- if you switch from Teflon washers to bronze phosphor washers, it's possible it may affect the the action of the knives.


BrFy33x.jpg
 
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Yeah, it's definitely interesting. On the Scimitar, the scale screw holes all have a tapered countersink (cone shape), which makes perfect sense because flat head screw heads themselves are tapered. The scale screw bushing holes all have a flat spot (flat tire shape), which also makes perfect sense because the screw bushings have a flat spot and this stops them from spinning while you're mounting the screws from the other side. The main pivot doesn't make sense in comparison. The main pivot screw hole doesn't have a tapered countersink (even though the main pivot screw itself is a flat head screw just like the scale screws) and the main pivot screw bushing hole doesn't have a flat spot (even though the main pivot screw bushing itself has a flat side just like the scale screw bushings). Who knows why?

It's almost the opposite case on the Black Talon (pan head screws all around), but just like on the Scimitar, the main pivot screw of the Black Talon also seems mismatched to its countersink. So the only thing that I can come up with as being the purpose of that extra washer (that sits in the countersink between the scale/bolster and the main pivot screw) on both knives is that it gives the main pivot screw head extra surface area to sit on. Maybe that's important.

I got to the hardware store again and I was actually able to fit the main pivot screw into their screw sizer. It was a perfect fit in the M4 x 0.70 slot, just like your Ti-Lite. However, it was also a good fit in the standard 8-32 hole either. Just out of curiosity, what kind of scale screw does your Ti-Lite use?
 
The stock handle screws for a Ti-lite 6 are M2.5 x 0.45, but I also use SAE 3-56 screws, which are a perfect fit.

I have a large assortment of brand new 8-32 screws which I use for things other than knives, and none of them would fit in any M4 x .70 pivots that I tried (I tried four pivots).

I tried to thread several M4 x .70 screws in a variety of 8-32 nuts, and although they easily threaded 1/8th of an inch into the nuts, they then came to an abrupt stop. Neither the diameters nor the threads of an M4 x .70 screw are a perfect match to a 8-32 screw. Those are my findings anyways.

It's my understanding that both the original Black Talon and Scimitar folders were made in Japan, and Japan uses the metric system. That's not definitive when it comes to screw sizes, but I'd wager the screws of both knives are metric.
 
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My screw sizers finally came in!

Black Talon:
Main Pivot - M4 x .70
Scale - M2.5 x 0.45
Pocket Clip - M2.5 x 0.45

Scimitar:
Main Pivot - M4 x .70
Scale - M2.5 x 0.45
Pocket Clip - SAE 4-48

The main pivot screws and scale screws were pretty much exactly as expected. However, I was not able to thread the scale screws into the SAE 3-56 slot on my sizer. They more or less just slipped through. The other odd thing was the pocket clip screws on the Scimitar. They were not metric. Maybe Cold Steel installed the pocket clips here in the US back in the day?

Also, does anyone have any advice on where to find PB washers for a pivot that measures roughly 5.5mm in diameter? Never mind. It seems 7/32 washers should do the trick?
 
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