Folder ?: need tip for grinding back of blade for liner lock

Kevin Wilkins

Kevin Wilkins

Knifemaker / Craftsman / Service Provider
Joined
Oct 7, 1998
Messages
1,486
Hi Folks, I'm getting on with my folder making and wonder if anybody has a good tip for getting that 8 1/2 degree grind on the back of the folder blade which makes contact with the liner? I've read (severral times) Bob Terzuola's excellent book, but I'm not sure how he set up his jig to give him the correct angle.

How do you guys manage it?

BTW I don't have acess to a milling machine right now...
 
I'm still experimenting but there are two good ways that I know of. On my framelocks I have a block of steel that I have ground to 7 1/2 degrees and checked with a protractor. I use that to tilt the table on my little Delta disc sander and set to the same angle. Once I have cut the lock, I then slowly and carefully grind the back of the tang to fit.

Another way is to tilt the platen on your belt grinder to the desired angle. ANd still another is to place a piece of 1/8" scrap on the platen and then, using that as a ramp, place your blade on top and grind the back. I have heard that that gives approximately 8 degrees. you'll have to experiment and see what works for you.
 
I did more or less the same as Peter suggests...I have a fixed table on my beltgrinder so I too a piece og flat 1/8 iron and fitted it so it has the sam size as the table. Then I drilled a hole in the two corners of the piece of iron facing the grinder, treaded for 2.5mm screws and put screws in from the top...now I can adjust the angle from 0 to about 12. I know Bob uses a small wheel...something like 4" but I found that my 10" wheel does a goodjob....I have yet to make the folder I made on this setup fail.
 
Im probably the last person that should be replying as i have never even tried to make one. But...when I read the book , my thought was that if you raised you blade to the just the right height on the contact wheel,(spacers to raise your work rest?) you could get the proper angle and a slight concave surface at the same time similar to the on he shows in the back of the book. I'm sure thats about as clear as mud, but it makes sense to me.:)
Good Luck
Leonard
 
Ok, i'll tell everybody the easy way to do it. First you don't need a milling machine. The angle on the back of the blade varies from maker to maker. I've seen it from 5- 8 1/2deg. I usually grind mine at 7 deg, not too steep, not too shallow. If you have a disc grinder tilt the table at the angle you want and press the back of the blade against it. Make sure you grind it the right way or your knife will turn into a lefty folder. I always grind the lock after heat treat that way I don't have to clean it up and worry about changing the angle. Bob Terzoula use a jig because he grinds the lock on his belt grinder, against the platen.

Peter,
I have tried grinding the tang to fit the lock, espically when I interchange blades and handles that look better switched, but it is tricky! Too much and you have wobble, not enough and your filing away till it fits. I always grind the tang first, install the backbar and draw a line accross the liner where the tang meets. I then cut out the lock and file it till it fits.
 
With typically Aussie disregard for the rules I just put the washer in place with the pivot pin and grind the tang to the washer on my 8" wheel...no jigs, no guides, just guessing the right angle. This works better for me than the angle guide and disc sander I used to use. Blowed if I know why it seems to work reliably but there you go...
 
I've decided that for me it is best to cut the lock close to where it needs to be but a bit long then grind the tang to fit. I make my mark by using a single edge razor blade or exacto knife then cut the lock out with reinforced Dremel cutoff discs. I use an air powered die grinder instead of the Dremel for a smoother cut. It takes me between three and four discs to cut out a lock on the thick stuff.

If I try to file the lockbar face what happens is I always end up with a rocking lock. I can never get it flat. Not only that but if I bend it out too far out to file it, it weakens the scallop and I recently had one break off. That's one of the bummers about building .125" titanium framelock folders....

What I wish I had was a thin cutoff saw with a tilting table kind of like a table saw with a cutoff disc. Then I could feed my piece in and make my cut exactly how I wanted it.
 
I haven't read the book and I'm still working out stuff on my first liner lock so I don't really know waht the hell I'm tlaking about;)
But I just thought that it might be easier, if you were to grind the whole face of the tang to the angle you want, and then grinding it back square above the lock face.
For that I would just tilt the table on my sander.
 
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