Lockback question

C

Cary A

Joined
Oct 20, 2011
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Hi folks looking for some help if I can get it. I have been working on my first lockback knife and have ran into a small problem that has turned into a huge issue. I have everything completed ground and heat treated, but when I go to start peening the knife together I keep running into the same problem. Everytime I peen the middle pin it locks the spring up, and the function of the knife goes down the drain. I am using O1 pins and O1 spring, I have tried peening just a little but the pin still swells to much. If anyone has any advice I would be very thankful.

Thanks,
Cary
 
If you spin the ends of the pin instead of peening them, there should be less tendency for the pin to swell in the middle. I saw a pin spinning set up in an old issue of Blade Magazine that utilized a drill press with a special insert and an anvil (for opposite end support). I can't remember which issue. You could also enlarge the hole in the rocker and put a bushing around the pin. The bushing would hold the handle slabs apart, and the rocker would pivot around the bushing instead of the pin.
 
Peen with a much smaller hammer, and light taps from the wrist only. You want to deform the head of the pin, not the shaft. Leave 1/16" exposed on either side and peen gently. Swap sides and test the knife until it snugs up.
 
The pin in the backspring is under tension.Its not going to move.If you really need to peen it,slip a shim between the spring and frame first so you dont compress it.
 
I have had the same problem many times. You would not believe my pile of unopenable lockbacks. Finally figured out to put 4 pieces of stainless steel foil between the back spine and the frame one on each side front and back of the pin. Also use a very small hammer and leave roughly 1/16 extra on both sides. Test after each couple of taps with the hammer. tiguy can you explain the spinning concept, I don't follow how that would work.
Thansk
Steve
 
SVanderkolff said:
Can you explain the spinning concept ?
I don't follow how that would work.
Thanks
Steve
Click to expand...

Doming pins is common in Jewelry applications

I think it works best on softer metals.
If it works on silver, it probably works on nickel silver too.

Does it work on stainless ? Anybody know ?


I know you have done gem inserts, maybe you can check your jewellery supplier catalogues for tools?

Basically, a small hard rod with a female domed shape is put into a drill press.
You run the drill press & the combo of pressure and friction forms the metal to a uniform and pretty nice finish.

Determining pin length would be important & I've no idea how that is determined.
 
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Buck domed the pins on the model 560 Titanium lock back folder. I think the pins were stainless because they were a bitch to drill out. Factory knives have their pins spin headed on specially made machines. The drill press set up I referred to above was more of a home shop/low volume operation. I am searching for the Blade Magazine arcticle that dealt with the drill press. My DVD Blade Discs don't seem to have an index or search feature.
 
In the book how to make folding knives by Lake, Centofante and Clay, Frank Centofante glued the center pin in with superglue. Since the spring is under tension the glue helps ensure that the pin will never come out.
 
Spinning pin heads is practical for production knives.
It's much easier to peen them. You can also use various sized cup-shaped punches to round and even up the peened heads.
 
I haven't made many lock backs, but I never peened that pin. I had read in a book and I "THINK" it was Frank Centofante that suggested not peening the leaver pin and using a touch of super glue to the outside of the pin. No mater how close your fit there is still a hair line gap that the glue can get into, put a drop on the outside of the pin, not on the whole pin. Since the pin is under tension it won't move. At least that's what I can remember.

Hope it helps.
 
Thank you all for the help using a smaller hammer worked like a champ. I will try the superglue next time.

Thanks again,
Cary
 
Centofante or not, unpeened backspring pins can "walk." It would take a very heavy hand to bind a backspring!
 
Superglue does not have a lot of resistance to moisture. Epoxy may be a better bet. I found the article in Blade Magazine entitled "How To Make Domed Handle Pins" by Terry Kranning in the April/May 94 issue. The two page article, complete with glossy colored illustrations, dicusses buying and/or making your own equipment as well as techniques for turning out great looking work. The old Blade Magazines are available on DVD. They may also have back issue or a copy service. I don't want to Xerox my copy for two reasons: 1) I would lose the color, and 2) I don't want to wind up in copyright jail.
 
Tank at www.tbarkcustomknives.com sells head spinners.
I have repaired/made literally thousands of folding knives, and the only heads I have ever spun were for factory authenticity.
A great way to dome pins is to peen them and simplt round them up on a polishing wheel.
You can also make cupped point punches to round up peened heads.
 
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