Liner lock lockup angle

Freds Edge

Well-Known Member
Can some one refresh me on the angle of the lockup between tang and liner , I am having a senior moment.
 

EdCaffreyMS

"The Montana Bladesmith"
I use 7.5 degree angle..... I have an old cast iron disc sander that is setup for ONLY that purpose with a 120 grit face/disc.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
I try to use around 9.5 to 10. It sometimes varies and I then hand sand using stones to bring it in by testing it.

If the lock sticks badly, it's probably too small of an angle. Easy to fix with hand stones or hand sanding. It's much harder to fix with your jig on the sander. You have maybe a thou or two to get it right. I use a 120grit stone by hand to adjust it. Then I follow up with a 600 or 800 grit stone.

If the lock slides and is slippery, the angle is likely too great and it's hard to save. You can maybe fix it with carbidizing the lock face on the Ti side. Maybe. Carbidizing might add a couple thou. After that much build up it just stops adding more.

In every case, I carbidize the lock face as soon as I can in the build to walk in the lock up. I rarely get it where I want it with just the grinder.

In my experience, anything less 8 or less will stick, anything more than 10.5 will slip. Your mileage may vary.

You can not judge how slippery or sticky your lock up is with an unhardened blade. A hardened blade face acts quite a bit differently than a soft blade.
I will polish a blade lock face and sometimes buff it. A smoother lock face gives you a more consistent lock up. A rough lock face wears quickly and changes the lock up.

I put a very small chamfer on the liner face corner where it engages with just the sharp Ti corner. If left sharp, this corner deforms quickly and loosens things up quite a bit. Carbidizing does help a little with this but I still see the corner deform/crush if not chamfered at least slightly. By small I mean 3 or 4 thou chamfer.

I do not make any with a small engagement for "future wear".
 

Stang Bladeworks

KNIFE MAKER
I use 10 degrees. I tried 8 and i was able to push the lockbar to 100%. It was solid but that bothered me alot. I checked alot of my framelocks and found they were about 10 degrees (hinderer, crk, spyderco). At 10 degrees my lockbar can't be pushed over and still is secure when spine whacked. There is no flex when applying negative pressure with my hands. It should be noted that different length lockbars will react differently. My knives have 3.5 inch blades. A shorter lockbar will change in angle faster as it travels over. I would think you would need a steeper angle to compensate for this but i haven't personally made a smaller framelock. I would start steeper and check it as soon as it locks up. Then if it slips reduce the angle by a couple degrees. This will give you a later lockup and you wont be able to keep trying this or you will quickly be at 100% lockup. I personally shoot for 30% lockup when finished. Hope this helps.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
Rooks better be writing some of this down. Great thread. There’s a bunch of ways to make a good knife. I love hearing how other guys do this knife thing.
carry on.
 

EdCaffreyMS

"The Montana Bladesmith"
This brings up a lot of interesting "learning opportunities" for everyone who builds folder that use a lockbar setup. We've already heard several options.... I have a good friend whom I consider a "Rock Star" in the tactical folder world, and he uses a "radius" (I believe he uses a 1 1/2" or 3" radius) on the back of his blades for lockup, and leaves the lockbar itself "square".... It's an awesome system, and he nails it every single time. The only reason I do not use the method, is because he uses a specially built "elevator" mechanism on a grinder that is designated specifically for that task (he spent a pretty good sum of $$$$ on building/machining the "elevator" system)...... and frankly, I'm just too darn lazy and stubborn to change a method that works for me. :) Lotsa way to skin the cat!!
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
I use a 2" wheel for my lock face. I think the very slight convex face gives you (slightly) more wear room.
 

EdCaffreyMS

"The Montana Bladesmith"
That's exactly what I surmised when I saw how the radius was placed on the back of the blade..... it also seemed to me that "kick off" would be next to impossible wit the radius. Maybe it's time for me to re-evaluate my stubbornness. :)
 

IanF

Well-Known Member
In Bob Terzuola’s book on liner locks he mentions using a 2 inch wheel to radius his blades lock face and 8.5 degrees. Hope this helps.
 

bladegrinder

Well-Known Member
On the blades lock face, after all is said and done I lightly touch it to a fine scotch bright wheel { not a belt }
that polishes the face a little and knocks off the sharp edge where the lock first engages.
 
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