Pivot and screw ramble!

D

Don Nguyen

Joined
Oct 4, 2011
Messages
1,043
I decided to try to make a friction folder, so I ordered a couple things from USAKnifeMaker, including a 3/16" pivot w/2-56 threads. The description said it had 1/4" TORX button head screws included.

I got some screws, but the screw head diameter is 5/32 - smaller than the pivot itself. Apparently the 1/4" is the length of the screws, according to customer service.

What's the point of having screws with smaller diameter than the pivot itself?? Am I missing something here? Do I have to counterbore the inside of the scales for the pivot, or buy separate screws?


Just aggravated. I messed up a potential friction folder yesterday too :(
 
You may have ordered the wrong ones or they made a mistake in shippig. As well 1/4" long may be too short . I just ordered sone 3/16 X 1/2" withe the 4 -40 screws. It's just another item. I did get the wrong ones myself once . Frank.
 
I am just confused. This is the one I ordered.

http://usaknifemaker.com/folding-kn...l-3-16-x-1-2-l-for-folders-w-2-56-thread.html


big_pivot1-8_3-16.jpg

Pivot 3/16" x1/2"L Barrel

Drilled and tapped for 2-56 Button Head
2ea 1/4" Button Head TORX screws included.
These are precision machined and stainless steel that have been heat treated.

Note: similar to picture
Click to expand...

I just assumed the included screw head was going to be larger in diameter than the pivot (looking at the picture, and reading 1/4" button head TORX screws in the description).

Customer service told me that they sell that pivot with the 2-56 screws, 1/4" length, 5/32" diameter screw head.


I'm new to all this stuff, but it just doesn't make sense to have the screw head size smaller than the pivot. Is this just the case with the 2-56 thread? Should I avoid that from now on and go with something else?
 
Last edited:
That's just the case with 2-56 screws.
The heads are smaller than 3/16
Screws are always described by Diameter (#2) Pitch (56) and Length (1/4") very seldom is head diameter mentioned.

If you want 1/4" head diameter look for a pivot with a 6-32 thread.

I can send you a few if you want, as I just got 500 made and in the shop yesterday.
 
Brian, that would be awesome! I really appreciate your generosity :)

I guess I wasn't thinking through when I initially bought them. I've already forgot stuff my machining classes taught me :(
 
I'm also curious, since I got a pack of the same ones unwittingly- where would you use these?
Only way I can think of right off would be with an exposed screw head on a bolster type folder.
Usually on a liner lock I use a hidden pivot screw head and spend some time getting the pivot length just right so that when the screws are cramped down on it the tension on the blade is where I want it.
With these, you couldn't do that, they have to go through some material smaller than the pivot, and just drilling a hole for the screw through liners wouldn't be a close enough fit to make the lockup solid.
Any ideas?
Andy
 
Don,
Anytime you get anything from us and it isn't what you want, send it back for a full refund. No problem.

These pivots are designed to be counter sunk into a liner with a through hole just large enough for the screw. The screw head may be countersunk as well. The idea with this size pivot was a be a bit stouter than a more typical 1/8", have it countersunk into a liner for a very strong pivot hold and the screws were a bit on small side simply for looks. It's an old, simple design and there are better pivots for today's bigger tactical folder. These maybe best used for oversized slip joints.
t


Don Nguyen said:
I am just confused. This is the one I ordered.

http://usaknifemaker.com/folding-kn...l-3-16-x-1-2-l-for-folders-w-2-56-thread.html


big_pivot1-8_3-16.jpg



I just assumed the included screw head was going to be larger in diameter than the pivot (looking at the picture, and reading 1/4" button head TORX screws in the description).

Customer service told me that they sell that pivot with the 2-56 screws, 1/4" length, 5/32" diameter screw head.


I'm new to all this stuff, but it just doesn't make sense to have the screw head size smaller than the pivot. Is this just the case with the 2-56 thread? Should I avoid that from now on and go with something else?
Click to expand...
 
Thanks tmickley, fully appreciated. I'm just new to this altogether, and it was only a single pivot so it didn't justify a refund in itself. It's been a learning experience for me.

I have a better idea of how these knives work now, so I should be able to make better educated purchases in the future, hopefully :)
 
I suspected there was a really sensible way to work with these, I had just never considered countersinking into the liner for some reason.
Thanks to Don and T for expanding my bag of tricks! I look forward to trying this on my next batch of folders.
Andy G.
 
Either countersink them into the liner/frame with a counterbore drill for a #2 screw, or just butt the pivot against the liner. The through hole should be .093".

The advantage of using this setup on a simple folder is that the clearance of the pivot between the liners/frames is always constant. Tightening the screws tight does not over-tighten the blade.You can grind the pivot shorter as needed to get the desired fit. Once the pivot length is very close to perfect, changing the washer thickness will allow the blade tension and fit to be fine tuned.
 
Thanks, Stacy-
Do you find that there's any play in the lockup using this system? I like having the liners/bolsters bear directly on the pivot pin, but if I drill an .093 hole in the liner for the pivot screw, then the tightness of lockup would depend on the liner bearing upon the threads of that screw. If it works it works, but it seems that it might wear or loosen before other systems.
Am I overthinking this?
Thanks for all the ideas,
Andy G.
 
Looks like I owe Don some thanks since I had thought about ordering these at some point, but had the same idea about them--that the screw head would be bigger than the pivot itself. I thought I could build a simple friction folder with four of these (pivot, stop, and two for the spacer) and just drill straight through and hold everything in place with the screws on the outside of the grip.

Since the screw head is so small on this item, what would be the closest thing on usaknifemaker.com to what we had envisioned? Something where you could drill a hole straight through and just have the screw heads hold everything in place. (Perhaps this is not an ideal way to make a folder, but it is simple.) Maybe this item although it would require drilling two different sized holes.
 
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