another lockback question

[gull wing]

how much "play" is acceptable? I mean up and down not side to side.
It does not "unlock" but a bit unnerving. I HAVE ONLY ONE THIS WAY OUT OF TEN LOCKBACKS (SPYDERCO).

[Andre V]

The play should be barely noticable.

[STR]

Just my opinion but lateral blade play is not going to affect it much if its slight. Vertical, while bothersome is also probably of little concern regarding reliability but I agree its bothersome on some. Half a mm is my limit personally. Anything more than that and I don't much care for it.

There are some things that can be done to help reduce if not eliminate that vertical play though. I'd have to see it but it may be possible to take that play out by making some small adjustments. Little hard to explain but it depends on the type of movement you experience and each one is different.

If the movement is the whole lockbar lifting up then its probably more to do with the pin holding the lockbar in place. In those cases most of the time the hole in the bar is slightly larger than the diameter of the pin which allows it to move slightly. We are talking like a hairs width or less but in a folder that is all it takes.

There has to be some gap in these in production pieces. Otherwise it would slow the entire process down but also the pins are mass produced and some just don't have the same measurements as others. Many times when I've rebuilt a folder that had some movement it was eliminated after I redid the hole to a larger diameter and installed a new tighter fitting barrel. At other times, and again depending on the type of movement one has it has been the same as when it arrived to me.

In these situations you have either the above situation with the lockbar pin, or the same thing in the blade. This can be by itself in just one spot or it can be both. On ones I don't have to redrill holes on, well, they don't change usually. Other issuses like the folder handle can also be responsible. On some older FRN folders for example, especially some used hard in their lifetime, the holes in the FRN can become oblong or almost oval in shape vs round which can allow play. Many times its hard to determine what causes it until its all apart and then I can zero in on it.

Still in other lockbacks it can be a combination of all the above, and a slight gap where the lockbar and blade mate up. That is why eliminating one thing in the combo can still leave it with play. Its all a crap shoot until you can get down to the insides and really examine one. Hope that makes sense.

STR

[gull wing]

thank you STR,
1. What is half MM = inches?
2. The lockbar is NOT lifting. There IS a slight gap. Caused by BLADE moving DOWN. (so it could be wallow in the BLADE or HANDLE?)

[PSU]

thank you STR,
1. What is half MM = inches?
2. The lockbar is NOT lifting. There IS a slight gap. Caused by BLADE moving DOWN. (so it could be wallow in the BLADE or HANDLE?)1/2 mm = 0.019685".

So it's about 2 hundredths of an inch.

[gull wing]

UPDATE:
I fixed it! Just lucky!
The problem was a very slight gap at the contact point of the blade and lock arm. I "stretched" the lock lever by hammer blow over an anvil, just a tad.
Now locks up tight and no bad looks.
Don't try this on the blade, too hard.

[STR]

Yes. This can work too but I usually only resort to this if all else has failed and try not to encourage it much since its very tricky usually to do for someone not used to doing it. If you look at many production and handmade lock back style folders you can sometimes see little hash marks, one on each side of the lock face that contacts the blade when it closes down with its snap. These are final adjustments or tunings to tighten the lock some before packaging usually. You don't see it as much these days with the modern machinery used compared to the old days when most all of the building of a folder was still done by hand but its still done on occasion when deemed necessary as I've noted on some Calypso Jr. ZDP knives, Cold Steel knives in the Voyager and Vaquero series and others that came to me for work already with those little indents on the locks. These can, depending on hardness of the lock, size of the hash indents to squish out a micron more lock contact and other factors wear down to allow the play to come back a bit but many times its years and years later if at all and usually only slight compared to what it was before the adjustment was done to complete the assembly.

One thing you have to watch for is going too much. Just like overpeening a pivot where you ruin the action this trick can also cause a lock bar to stick, or not seat all the way down and should only be done by someone with some experience in how to fix it should it be taken too far. On knives that don't come apart this can be a bad idea to try since its always best to be able to get the lockbar out separate from the other parts to do this.

Glad you got it fixed up. Sounds like you hit it right and followed the golden rule of knowing when to leave well enough alone without going too far. Good job. :D


STR