Lock geometry question

[Lapedog]

Material isn't being abraded away as much as it's being moved and compressed under the force of the ceramic ball.

Definitely can see that. On my regular ti liner/framelocks you can see a little black mark on the tang where the lockbar is being worn away.

(That mark also prevents lock stick. Cleaning it off can bring lock stick back)

I wonder how much work hardening the ceramic ball on crk locks causes to the tang, which you noted is being more compressed/displaced by the ceramic bb.

 

[bhyde]

Definitely can see that. On my regular ti liner/framelocks you can see a little black mark on the tang where the lockbar is being worn away.

(That mark also prevents lock stick. Cleaning it off can bring lock stick back)

I wonder how much work hardening the ceramic ball on crk locks causes to the tang, which you noted is being more compressed/displaced by the ceramic bb.

I may be able to talk to the guys in the lab at my regular full time job and see if they can check it. Micro hardness tester in there I believe.

Here is the term for it and good thinking about it hardening because that is exactly what is happening.

https://en.wikipedia.org/wiki/Burnishing_(metal)

 

[ATJ999]

Take a sharp pencil and rub the pencil "lead" where it is locking up. Works for me every time.

 

[Lapedog]

I may be able to talk to the guys in the lab at my regular full time job and see if they can check it. Micro hardness tester in there I believe.

Here is the term for it and good thinking about it hardening because that is exactly what is happening.

https://en.wikipedia.org/wiki/Burnishing_(metal)

I heard this is also what is happening to high hardness vanadium carbides when they are being sharpened with a medium that isn’t hard enough to “cut” them.

At the same time I hear that those vanadium carbides are burnishing a stone like my AlOx sharpmaker rods which leads to the degradation of the sharpening ability.

 

[marrenmiller]

The only reason the single point of contact is not an issue on the inkosi/umnumzaan etc. is because the ceramic ball on CRK knives is harder than the actual blade tang, the wear is on the tang. The single tiny edge point of contact is still an issue with knives that use untreated titanium lock bars.

And if it was titanium with carbidizing or carburizing, then that would also be the case that the lockbar end is harder than the blade tang. Maybe I missed it, but there's a good chance that the OP's knife is treated in one of those two ways as it's a fairly common feature on high end frame lock knives.

In any case, it really shouldn't matter if untreated titanium lockbars initially lock up on a small contact patch or a large one, so long as it can wear in over time. Some knives, like the striders from years past, weren't designed well to allow that. A smaller contact patch will mean faster wear till everything isbsettled, but with treated ti even that isn't a problem.

In any case, I stand by my original comment, which is that it should be contacting in the inside lower corner of the lock bar. The fine details notwithstanding, that's how the lock is designed to work.

 

[Mick_1KRR]

And if it was titanium with carbidizing or carburizing, then that would also be the case that the lockbar end is harder than the blade tang. Maybe I missed it, but there's a good chance that the OP's knife is treated in one of those two ways as it's a fairly common feature on high end frame lock knives.

In any case, it really shouldn't matter if untreated titanium lockbars initially lock up on a small contact patch or a large one, so long as it can wear in over time. Some knives, like the striders from years past, weren't designed well to allow that. A smaller contact patch will mean faster wear till everything isbsettled, but with treated ti even that isn't a problem.

In any case, I stand by my original comment, which is that it should be contacting in the inside lower corner of the lock bar. The fine details notwithstanding, that's how the lock is designed to work.

Unfortunately carbidizing isn't permanent tho, and the lock bar often benifits from re-carbidizing later as the partials wear away over time. It's quite different to CRK's carburizing as i'm sure you are aware of already which seems to last much longer. Hinderers have some carbidizing on the lock bars and they still wear away with use, i had 2 XM-18's with carbidized lock bars wear down over not too long a time period. Anyways, it would help if we had some close up pics of the OP's knife, i'm sure there's an explanation somewhere. Cheers

 

[Wowbagger]

Recently dropped over $400 on a folder and the lock stick is driving me crazy.
I've cleaned it, graphited it a few times, cleaned it again, sharpied it a couple times, and it's still sticky.

I say send it back and buy two Spyderco Para 2s maybe get a Benchmade 940 while you are at it. For the same money
Then send a photo of them to the maker of Mr Sticky and say "Hmmm these guys know how to make knives that work what's your excuse ?"
But that's just me.

 

[Wowbagger]

I've noticed that with some titanium frame locks or titanium liner locks that there will be lock stick when they are clean, but the stick goes away if you keep feeding them graphite and keep using them. My Emerson is like this. Zero lock stick until I clean and/or lube it, then terrible lock stick for about a week.

Sounds like a lot of work for not much return.

 

[Heirphoto]

Being a "low speed, don't even know what drag means" kind of guy
I am still puzzled by the Mick Strider comment....why would an "operator" appreciate lock rock?

Can't wait to hear the reasoning on that..