linerlock question, problem, HELP

After making a few liner locks and scraping a few too. I have a question or problem I would like to resolve.

I have noticed sometimes my locks tend to be sticky or tightly wedge against the back of the blade when the blade is really snapped open. For instance, if you rotate the blade about half way or a little more open and then snap your wrist to sling the blade open, this will cause the lock to really be forced into the back of the blade and make it hard to release, sometimes requiring use of both hands to release it. You "USUALLY" can't cause the lock to stick or wedge with your normal thumb open even a forceful one. But sometimes a hard thumb open will cause the lock to be tight.

I have tried everything I can think of or read in "Tactical Folders book".

My lock is cut about 7 1/2 degrees. I round off the top of the lock on the blade and the spring so the top edge of the blade doesn't "dig" into the spring. I have about 1/8 of an inch contact between blade and spring (lock) that occurs about 1/16 of an inch below he top of the blade. I don't have any sharp edges where the lock slide onto the blade. I don't have any sharp edges on the lock face where it meets the blade. I believe my pivot is tight the lock pin is tight. Blade is centered. Lock just reaches the other side of the knife so it is not over bent.

I have never tried other peoples lock to see if they would do this. Some how I don't think they would appreciate it.

I don't know if this is normal in forceful opening, is it? What can I do to fix it? Any ideas would be appreciated.

First of all, I no longer make ANY liner lock, but the polish of the flat faces where the blade and lock meet is important.
How do you cut and polish the 7&1/2 degree faces?
(both lock face and back of blade)
Next consider the blade stop.
The tiniest bit of lint of dust caught between the stop and blade will change the point of lock up.
If a heavy blade is SLUNG hard enough , it can cause flex in a pivot that has been hollowed out and threaded.
I assume this is not a SOLID rivit pin we are talking about.
Most today are threaded.( at least the front pivot for the blade)
It is usually a threaded fitting used for the blade stop too.
How much clearance do you have between the screw and hole of the liner, ect?
You are either getting a flex in the fittings or fit up or screw movement, it sounds to me.

lock on the blade is cut with a disc grinder but then filed using a filing jig set at 7 1/2 degrees. After heat treat I polish it with used piece of 320 grit paper in the jig again. So I'd guess it is 400 grit anyway. Use same paper and eyeball the spring on the liner.

Yes the pivot is 3/16 with 4/40 screws. Stop is hardened steel dowel pin 1/8. Blades are 3 to 4 inches long and .100 to 1/8 thick, depends on knife. I ream my holes so I think the fit is tight on the pivot and stop pins. There is no side play on the blade and I do my best to keep everything parrallel us a micrometer on everything.

Tony,
First I suggest a bigger stop pin, 1/8" is kinda small for that sized knife.That may stop the flex in itself.
The play is probably quite small in compairison.
During regular use, it works fine, but when you sling the blade it locks up, sounds like flex to me.

Can you see rub marks on the lock face?
This would indicate high spots that need dressing.

How much play is in the blade just before it locks normally?
Side to side play while closed?
How thick is the locking strip you cut back?(from liner)
And how tall?(1/2"-3/8"or what)
Are they titanium liners?What grade?

Tony there are a lot of variables.
Check out these points and get back to me.
If you need to call, feel free.817 451 8243
I'll help you all I can.

Gene,

Only rub mark I have seen is on the liner lock spring or arm. It is about 1/16 to 1/8 inch wide where it contacts the blade. Nothing on the blade. I would figure that to be normal, yes or no?

Really no play per say on blade half opened or closed. I tighten my blades until they are hard to move and then back off a little until they are smooth but will not move with gravity alone. You have to move the blades. I use .015 teflon washers. Would brass or copper be better?

Lock strip is about 2 to 2 1/4 inches long with 3/8 inch wide. Liners are titanium 6-2-4-2 instead of 6-4. It appears to be a little harder alloy of ti.

How big a blade stop do you recommend for 1/8 inch or less blade up to 4 inches?

Tony,

Tinanium has a natural affinity for steel and if both your surfaces are not finished really well the spring will tend to gall. I only make small liner-locks and use lock-backs for the bigger pieces (less hassels).
I also am very careful how I bend my spring, too much tension will make it difficult to unlock also. I fit mine up so the spring is only its thickness inside the lock as if it travels too far across the lock it is difficult to unlock.

Regards from Australia

Tony,
The rub mark is a sign.
you should not see any rub mark, or just see one all the way accross the face of the lock.
1/8" mark tells me that youl lock is uneven, which as Niel said, causes it to guald up.
You may have it bent too far as well.
3/16" minimum for the stop pin. The stop pin HAS to be bigger then the blade it is going to stop.
A 1/16" pin will not stop a 3/16" blade, nor will a 1/8" pin stop a 1/8" blade. Make the pin larger than the blade thickness.
Washers are best out of hardened steel like feeler guage material.Harder than the liners but softer than the blade.
Brass washers stick.(drag)
Copper ones are much smoother but wear out too quick.
I couldn't tell you about the plastic ones.Never used them.
6-2-4-2-is fine, but you might try a 1/2" lock blade for a large knife, and 3/8" for the smaller ones.
also, try to get the lock to engage sooner so it doesn't swing over so far that it gets locked up.(the lock to be .010 " longer)
I hope this gets you going.
You have my # if you need it,OK?
.......................................BE BLESSED...........................