Friction folder questions...

Chiro75

Chiro75

Joined
Feb 4, 1999
Messages
5,786
I am playing with the idea of making a friction folder. This would be the first knife I have done on my own. The idea comes from Wayne Goddard's articles, of course, but I did have a few questions... I would assume the following design: blade, pivot pin, stop pin, open back if possible, dual stainless liners, and scales over the liners. The questions:
1) What material for the liners? I have a sheet of pretty thin stainless, but I don't know the "pedigree". Probably 300 or 400 series. Is this good enough?

2) What size and material should I use for the pivot pin and stop pin? I have a good selection of stainless rod stock available at the hardware store, as well as "music wire" which is hardened carbon steel.

3) Should I consider a pivot screw for adjustable tension rather than a pin?

4) Should I use screws or pins to hold the handle scales in place? I don't have any tapping equipment. Also, in terms of using screws, how does one countersink the area around the drilled holes so the screw head fits below the surface of the handle material? Is it sufficient to just use a larger drill bit and drill partially into the material or would I need some sort of bit that does a more precise job? I do have a drill press, now, so that helps!
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5) I had trouble understanding Wayne's drawings. Where does the the friction to keep the blade open come from? Will this type of folder have slow, resistant opening?

6) What should I use for washers, and where can I get these materials?

Also, if anyone has any materials they would care to donate for this project, please let me know. I would compensate shipping and possibly trade services for the stuff. I think all I really need, assuming my liner material will work, is a piece of steel for the blade. i was thinking of something fairly short and broad. A piece of steel around three inches long by 1.25" wide or so would work fine. I want this knife to cut well, so I would need it to be pretty thin. I also wouldn't mind something like 01 or 1095 or something like that that I could heat treat myself using crude methods (i.e. torch and homemade quench). Stock of 1/8" or the nect thickness up would be fine. Also it would cut down on the amount of work I would have to do to make the blade, which will be done with hand tools and a little help from a 6" bench grinder with a 60 grit wheel. Anyway, this is a side-project that will take some time, but if you have a scrap of steel that will work for me, I would gratefully accept! Any information would be much appreciated, too.

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My Custom Kydex Sheath page:
http://www.geocities.com/CollegePark/Lab/1298/frames.html
Palmer College of Chiropractic
On Two Wheels
agocs_s@dd.palmer.edu
Madpoet (Mel Sorg, Jr.) Tribute page:
http://www.geocities.com/CollegePark/Lab/1298/madpoet/main.html

 
Chiro,

I'm hardly an expert since I'm working on my first two friction folders now (both from Mel Sorg blades bought at the auction recently), but here goes:

1) Since they'll be flat and not required to provide springs of any kind, the material for the liners is (I think) non-critical. I've seen may old friction folders with no liners at all.

2) The two blades I bought have different size pivot holes. One is 1/8", the other 1/4". I'm guessing that one was intended for an adjustable pivot, the other for a staked pivot. As far as stop pins, 1/8" (although not much less) should be sufficient unless you anticipate really heavy usage or you plan on a very large blade. A lot will depend on the folded vs. unfolded blade positions of your design, and the amount of space in between for locating the stop pin.

3) I plan on using an adjustable pivot on both of mine, even if I have to use a carbide drill to open up the hole in one blade. Goddard's articles describe staked pivots. It depends on whether you're trying to get a reasonably authentic reproduction, or a knife that you don't have to "tweek with a hammer and punch" when you want to adjust the tension. All of the antiques I've seen have been staked.

4) See 3) above. I plan to use screws. You can find countersink bits to use in your drillpress after drilling the body hole in the scale. You may also be able to get an all in one drill that drills the body hole and has a countersink of the right size at the top. You can also use socket head cap screws by using a piloted counterbore or counterbore drill. Most of the knife making supply houses have at least some of these. Davenport should also have an industrial supply house with a walk-up counter where all of these things can be purchased. As far as tapping holes, there are several expedients for making sure the tap goes straight. The easiest is to use your drill press to drill a hole just a little larger that the outside diameter of the tap in a block (metal, micarta, hard wood) tall enough to keep the tap upright. Locate the block over the hole to be tapped, insert the tap and tap with "great care and sensitivity" as my shop teacher used to say.

5) Tension in the pivot provides the friction. Also, your hand serves to hold the blade in place while you're holding the knife in a conventional manner. (I know. It's the antithesis of the modern lockblade.) Some friction folders have what's called a "saddle lock" to keep the blade from folding. One of the folders in "knives 2000" has one. There is also nothing to prevent you from incorporating some more modern lock into the design. I may or may not do this with mine. The vast majority of the antiques I've seen have nothing but friction and the web of your hand keeping the blade in place.

6) Most any of the knife maker supply houses have bronze and teflon washers in various sizes. Also the industrial supply houses.

Again, you may get posts from folks with far more friction folder experience than I. You would do well to listen to the more experienced hands.

Good luck,
Bob Couture
 
Okay, thanks. I took a second look at my proposed liner material and it is PLENTY tough! Some other things pop up...I have some extra REKAT scale screws, which are really tiny. These are the ones found on the Carnivore, Pioneer, etc. Anyone have any idea what the size is for possible tapping? I MAY be able to use REKAT's method for joining everything together, if I can find a tap that fits those screws as well as tubing that is the right diameter for the tap as well. I could cut spacers from this tubing, tap it, and use that for the screws to thread into. This is how the two REKAT folders I mentioned work.
Because this is far from a repro project, I would like the knife to be as usable as possible. Considering the friction comes from the pivot/tang joint and not from elsewhere, this means that I could copy Sean Perkins and forego the "tail" on the tang. Also, what do I need to do to make the pivot adjustable. When taking folders apart, it looks like the pivot pin is exactly the same size as the hole in the blade, and the pivot is sized such that it doesn't fit flush on the both ends. The action of tightening the pivot screws, then, tightens the scale and frame to the tang, thus causing the necessary friction to keep the folder somewhat safe to use. Is this how it works or am I missing something?
Basically, then, the challenges will be as follows: grinding a decent blade on a crappy setup, heat treating the blade, and finding the necessary taps, screws, and countersinks. What a project!

------------------
My Custom Kydex Sheath page:
http://www.geocities.com/CollegePark/Lab/1298/frames.html
Palmer College of Chiropractic
On Two Wheels
agocs_s@dd.palmer.edu
Madpoet (Mel Sorg, Jr.) Tribute page:
http://www.geocities.com/CollegePark/Lab/1298/madpoet/main.html

 
Chiro,
Make sure to post some pictures of your first folder. There is nothing like the feeling of accomplishment when you actually do something on your own for the first time.

Good luck with your endeavor!

C Wilkins
 
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