A question about lock-up

[RayseM]

How little lock up is really needed to secure a blade?

Two photo examples -

1) Seems small but OK




2) To my eye this one below, seems to have a small percentage less lock to blade overlay and right on the hoary edge of not enough.

Any comments - OK or not acceptable?



I'm pretty sure that lock bar tension has as much (nearly as much anyway) an effect on smooth and easy flipper action as the quality of the cased ball bearings. Is leaving the lock bar tension at just barely grabbing an acceptable technique to insure a smooth and easy flip.

Thanks for enlightening me.

 

[RayseM]

If this isn't the right forum for this question/thread I would welcome it being moved. Didn't know what category of forum would be best.

Thanks. Ray

 

[Ajack60]

Lock up is a personal preference, I'm a little more cautious with knives that have early lock up. Not that they would fail, it just gives ma a warm fuzzy feeling making sure I've got a hold of the lock bar during use. Personally, I prefer later lock up in the 30% to 70% range.

Yeah, both knives have early lock up IMO.

 

[HeavyHanded]

I hate to say it, but from my experience you cannot really tell lockup by visual examination. Even a slight overlap can hold to the physical limit of the steel/titanium's flex point.

If at all possible, place the blade in a padded vice, edge up, stand on a scale, and apply pressure to the handle - gloves or some stand in for your hand are a good idea. Only you can decide what a good number is for the lock to resist - normally you will see it begin to flex before it fails and the lock falls off the interface.

Is also possible the failure won't result in the blade releasing, but rather it will take a bend and maybe be ruined. If you see it begin to flex I'd note the poundage above your body weight and stop. Likewise if it slips off its rest I'd note the poundage.

I'm certain there are plenty of good liner and frame locks, and I still own and carry a few, but I don't trust them compared to other lock types anymore after testing a bunch. If it doesn't pop off during regular use I wouldn't worry.

 

[RayseM]

I hate to say it, but from my experience you cannot really tell lockup by visual examination. Even a slight overlap can hold to the physical limit of the steel/titanium's flex point.

If at all possible, place the blade in a padded vice, edge up, stand on a scale, and apply pressure to the handle - gloves or some stand in for your hand are a good idea. Only you can decide what a good number is for the lock to resist - normally you will see it begin to flex before it fails and the lock falls off the interface.

Is also possible the failure won't result in the blade releasing, but rather it will take a bend and maybe be ruined. If you see it begin to flex I'd note the poundage above your body weight and stop. Likewise if it slips off its rest I'd note the poundage.

I'm certain there are plenty of good liner and frame locks, and I still own and carry a few, but I don't trust them compared to other lock types anymore after testing a bunch. If it doesn't pop off during regular use I wouldn't worry.

I wondered if that might be the case and that I was creating a problem where none exists. Would you say then that for a "gent's" light duty knife with a 3" or less long blade (less leverage on the lock) that the lock up shown in the photos is likely good for all except extreme (ab)use at which time the lock slipping might be the least of concerns?

Thanks for the replies.

Ray

 

[HeavyHanded]

I wondered if that might be the case and that I was creating a problem where none exists. Would you say then that for a "gent's" light duty knife with a 3" or less long blade (less leverage on the lock) that the lock up shown in the photos is likely good for all except extreme (ab)use at which time the lock slipping might be the least of concerns?

Thanks for the replies.

Ray

I'm not sure I'd worry about either especially if they are newer knives with not much use so far. They will break in and engage a bit more up to a point. Attempts to get more engagement could have it developing slop after a few years.

The only stress test I still do on new ones is to clamp in a vice and apply no more than 10 - 15 lbs of force. If it doesn't pop right off at that level, it'll likely hold to destruction (I was surprised that some actually will pop right off using this test). If it can't tolerate that much before bending or disengaging I'm not sure I'd want to carry it.

 

[killgar]

My 2 cents.

Just going by those pics, and assuming that there is no lock slippage when a little pressure is applied to the back of the blade, I wouldn't have any problem with that level of lockup on a framelock for the things I use a folder for.

I've been carrying a framelock for almost a decade (Bradley Alias 1). I use it at work (construction) for what I would call "light duty"- cutting plastic wrap, twine, tape, etc.

I regard the lock on a folder as a mechanism for keeping the blade open, I don't rely on it to protect my fingers, no matter how strong the lock may be. I don't use a folder in any way that would tend cause the lock to fail or put my fingers at risk.

I don't use a folder for cutting the tops of 50 gallon steel oil drums, so I don't require MAXIMUM lockup .