What should I use for slipjoint pivot material ?

C

chopperknob

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Nov 3, 2008
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Hi folks , I've recently started making slipjoints with traditional construction methods , but have recently run into problems with pivots !:grumpy: I am doing a small batch of swayback Jacks that have stainless bolsters and I have used a stainless pivot and peened /domed it before sanding flush for an invisible look . But my problem is this , after a few dozen openings the spring is no longer flush in 3 positions and the action gets stiff and feels like it is galling. On removal ( drilling out and much swearing ) of the pin , it is evident that the pivot is too soft and the blade has worn it . . . . :mad: What grade of stainless should I use ? I can heat treat carbon steels but do not have the ability to harden / temper stainless , so I am looking for a grade that I can machine to size and peen but is hard enough to last in it's SUPPLIED state . . . . My folders up until this point have a nice smooth walk and talk and are not nail breakers , the spring is not preloaded hugely . . . The blades are 01 steel rockwell 58/59 with drilled and reamed holes and I machine the pivots from 303 bar stock on my lathe to close tolerances ;) I have noticed on some of my production knives it seems they use brass or nickel silver ! How is this possible ?:confused: So come on guys , what do you guys use and where do you get it ? Thanks in advance
 
My limited experience sez that "peen" and "hard" are going to be mutually exclusive.
Why not use a bronze or stainless bushing? Here are stainless ones from Alpha: http://www.alphaknifesupply.com/hardware.htm
The blade turns on the bushing, so that gives you more flexibility on what you use for your pin.
I hope some of the Big Kids chime in, this is a concern for me, too.
 
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I don't know, I've used 303 for slipjoint pivots and haven't had that problem. Are you absolutely sure it is 303? Was there any side to side play in the blade?
 
elementfe said:
My limited experience sez that "peen" and "hard" are going to be mutually exclusive.
Why not use a bronze or stainless bushing? Here are stainless ones from Alpha: http://www.alphaknifesupply.com/hardware.htm
The blade turns on the bushing, so that gives you more flexibility on what you use for your pin.
I hope some of the Big Kids chime in, this is a concern for me, too.
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Hi elementfe ,thanks for your reply . Unfortunately the blades are already ground and heat treated and have a 3.5mm hole . The liners also have covers rivetted on and the bolsters also have a 3.5mm hole . . . So no chance for a bushing now :grumpy: I will check alpha supply ( thanks for the link ;) ) although I should add that I'm not in the states either ! Double :mad:
 
leifjl said:
I don't know, I've used 303 for slipjoint pivots and haven't had that problem. Are you absolutely sure it is 303? Was there any side to side play in the blade?
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Hi ,thanks for your reply :D I'm pretty sure it's 303 ! There was no side to side play , the pivot was still proud ready to beat on some more if it needed it ! I was at the open /close / oil /repeat part when I noticed the walk change and thought that maybe the tang was galling the spring, but the reamed /polished hole was galling my beautifully finished pivot instead ! ! It is strange , I have used 300 series before on a knife that is still going strong and which has a similar action :confused: Maybe that pivot work hardened more when I machined it ?
 
That sucks. Someone with more experience than me will probably chime in.
A 400 series pin, like 416, can be hardened and made softer by heat treating, maybe if you get a hardened pin and place in a pin vice with like a 1/4" or so sticking out you can heat the ends and it'll leave the center of the pin hard and soften up the ends enough to be malleable. Just a thought.
 
I use 3/32" 416 SS pin stock for my pivot, I drill the blade at 3/32 then after H/T ream with a #41 carbide reamer. leaves about .002 clearance.
If your pin and pivot are a close fit,when you peen it together the pin will swell,as you open and close it the pin warms up and swells and starts galling,once it starts it's a losing battle.

Stan
 
I think you are right Stan. I used to do them the way you do until I started using bushings.
I use 416 stainless, personally I do not like 303,had some bad experience with it.
 
What problems did you have with 303 Calvin?
Just wondering if I should avoid the stuff for certain uses.
 
I also use 3/32" 416 pin material and never any problems. Mostly use bronze bushings now though.

I did make a few hundred slip joints back in the 90s' with nickel silver pins and no problems there either. Heck, I have a bunch of very old slip joints with NS pivot pins that are well used and still fine...
 
Thanks, Stan! I'm also trying to learn everything I can about this.
Oversizing the hole makes a lot of sense, as does slightly countersinking the pivot hole on the blade and the inside of the liners, so there's somewhere for the metal to go when you upset the pin by peening it.
The thought of using 300 series stainless gives me a headache- I do a lot of fabrication for restaurants and for decorative railings and such in 300 stainless, and I can't wait to get back to working with the 410 and 416- it's such a dream to work with in every way- no broken, burned, dull bits, it just does what you need it to do.
 
leifjl said:
What problems did you have with 303 Calvin?
Just wondering if I should avoid the stuff for certain uses.
Click to expand...

It doesn't cooperate very well when trying to machine,want I call gummy or sticky,likes to gall.
I threw out what I had left and banned it from my shop after I accidentally used it for a pivot pin in a slipjoint with 416 bolsters,it worked well but you could see it from a mile away because its a different color from 416.
 
I agree with Calvin,won't use 300 series SS in my shop,gummy, hard to work and tends to gall. Even when using it for bolsters on fixed blades,it's just harder to get a good finish on.

Stan
 
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