Slipjoint pivot material ?

C

chopperknob

Joined
Nov 3, 2008
Messages
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Hi folks , I have also posted this in the knife making section , but after lurking in this section for years , I know you guys have a wealth of knowledge here , and that a few of you even do this knife making thing for a living !So I'm hoping one of you experts can help me . . . :D 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
 
You want 3/32" annealed 410 SS stock. I buy it from USA Knifemakers Supply. You are probably using 410 or 416 bolster stock so this fades right away when piened.......you hope! It does not wear out. You must also slightly round over the corners of the tang on the blades or they will gall.
 
How much clearance do you have between the pivot pin diameter & the pivot hole in the blade?
 
Hello. I am new to the slipjoint making myself but I use and really like the bushing construction method. My knives use a 3/16" bronze bushing that the blade pivots around. Then the knife is held together with 3/32" nickel silver pins. The pivot is slightly thicker than the blade so you don't have to worry about blade pinching when peening the pin. I want to try stainless but I have alot of ns left. Check out the Bose knife website and look at the pivot bushing tutorial. It takes more time and some more tools but I think you will find it is worth it. Now if I could just find time to build more.....

Nathan
 
Be great to see some of your work chopperknob :thumbup:
 
John"s post above is right on, 410 pin stock should outlast most of us. I've worked on
folders 85-100 years old with N/S pins still in good shape. The closer you can get the
tang and bottom of the spring to absloute square will help, and also eliminate a number
of the galling problems. How much preload ? round the corners on the tang ends and never
put it together during assembly without grease or oil even for trial fit ups. Dirt and crud
are the enemy of slipjoint actions. I've seen silky slippy actions get ugly fast with either.
I usually preload @ .035-.040 of spring rise. It will put a smile on your face when you get
one back after 5 or so years of pocket time for a "fluff and buff" and the pin is'nt showing.
Peening is an art.
Ken.
 
Thread like this really puts some perspective on thise thousands of slipjoints made and used trouble free over the last couple hundred years or more!
 
It certainly is great to see makers like Ken and John take the time to offer their expertise in this forum.
 
Hi guys ! Thankyou to everyone who has taken the time to respond and pass on their knowledge ! It's what makes this forum great ;) I am really beginning to suspect a rogue piece of material ! I have machined a new pivot and it's in there un-peened and I'm gonna see if I can make it happen again :D Thanks again guys I appreciate it .
 
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