View Full Version : pivot pin question.


SkaerE
04-14-2003, 06:56 PM
generally, is one end of the pivot pin press fit into a liner? (on a liner lock or frame lock folder)

and why are the two washers different sizes? (seems the one on the screw side of the pivot is much smaller)

yes, i was taking apart some of my knives ;)

Ray Rogers
04-14-2003, 08:04 PM
Depends on the maker. I like to press fit my pivots into the bolster but I also have made many folders that have screws on both sides and the pivot is not pressed.

The screw side washer is usually smaller to allow clearance for the lock bar to pass. The other washer is larger because 1) it can be, and 2) that gives more support to the blade 3) it keeps the lock bar from moving past the blade and jamming between the blade and the liner ......

SkaerE
04-14-2003, 08:06 PM
excellent! thank you very much.

whv
04-15-2003, 05:39 PM
i've also seen makers use large washers on the lock side. they make a cutout in the washer to clear the lock, then superglue it to the frame/liner so that it won't rotate to interfere with the lock. works great with nylatron.
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whether you plan to build folders or not, i highly recommend the peter atwood video (http://www.realrates.com/knives/video1.htm) on making a framelock. lots of good info in one place.

Kevin Wilkins
04-16-2003, 01:54 AM
I use a 0-80 cylinder head screw on the Tangent with the pivot head, then I machine a half radius in the pvot head. This keeps the pivot from rotating and allows the knife to be taken apart during assembly. Heres a few pics:

http://www.wilkins-knives.com/pics/pivot_1.jpg

http://www.wilkins-knives.com/pics/pivot_2.jpg

PeterAtwood
04-16-2003, 06:26 AM
Nice method there, Kevin. :)

Thanks for the mention Wayne! Lately I've been making smaller knives and have had to cut down my washer size quite a bit. I've been using phosphor bronze exclusively for awhile now and find that they can also be cut down for lock slot clearance leaving plenty of meat elsewhere for blade support and then superglued in place.

Kevin Wilkins
04-18-2003, 06:11 AM
Thanks Peter!

I must say that I'm not in favor of using superglue and cut out washers. For me this is not a mechanical solution, it's more of what used to be referred to in my automechanic days as a "silver tape job"... means taping the #### thing together and hoping the customer leaves the state before it falls apart.

I think Strider uses this method on the AR folders and I have read in their forums where some users have had problems with it. I havent bought one yet because of this, although I really thing the industrial design of the knife is brilliant.

Super glue and all other glues will degrade over time and through exposure to oils and solvents. If this happens and the wsher rotates, this renders the knife unusable which could be a real drag. Why not solve the problem in the design phase before it becomes a problem? There are a number of mechanical solutions whih would keep the washer from rotating or simply design the knife so that this isnt a problem at all. Most of my folders use washerrs of 2 sizes, one on the lock side and the larger one on the non lock side. For larger folders I design the lock for clearance so that I can use large washers on both sides.

Of course its also all a matter of time and costs. My folders start at a bit over $500 and take about 30 hours to make. I had the bronze washers made to my specs in the USA and they cost quite a few $100 too. I now have washers for the rest of my life though... ;-)

jimroe
04-30-2003, 06:25 PM
Fascinating thread. I wrestled with this one as I really liked the idea of large washers on both sides of the blade. I rejected the idea of Superglue for the stated reasons but came up with a mechanical solution:

I drill a 3/32 hole in the locking liner so that it falls within the diameter of the washer. I punch a matching 3/32 hole in the washer, and cut out the washer for the lock. I press a brass rod into the hole, and cut it flush to the liner on the outside, and leave it .012" protruding on the washer side (I actually mill it to this dimension).

The punch I use is the trick part that makes this work. Handmade, it works like the shim punches you see with a clear plastic top and a hardened base and different size punches to make precision holes. Mine has a locating dowel to hold the liner and the washer in position (just like the pivot pin will) and allows me to run the punch through the hole in the liner (before I press the brass pin in) and punch the hole in the washer exactly where it needs to be.

When assembled, the brass pin prevents the washer from rotating, but is a few thousands shy of actually contacting the blade - I use brass just in case it would drift a bit towards the blade, though that's never actually happened.

Kevin Wilkins
05-01-2003, 04:06 AM
Jim:

That's a solution to warm any tool maker's heart! Hats off to ya man.

PeterAtwood
05-01-2003, 06:04 AM
I'm using very thick washers so that is a nice solution for me as well. Thanks for the good tip! :)

whv
05-01-2003, 05:29 PM
sounds like a good way to go, jim.
& welcome to ckdf!
thanx

Mick Strider
03-02-2005, 11:40 AM
I think Strider uses this method on the AR folders

On the very first run of AR/GB's we bonded the bearings to the liners.

It was not to keep them from moving. It was to insulate them from the dissimilar metals.

The first ones of those knives were made to go to a job where this would have been an issue. That issue has long since passed...as have the bonded bearings.




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