Interesting topic, Anarchy, and one that, along with any discussion of lock wear, travel, geometry, etc, always raises a lot of opinions, theories, and hackles to boot. So far, an interesting and civil discussion here. :thumbup:
A few random thoughts and really no conclusions:
>My impression has always been that the purpose of steel lock-bar inserts is indeed two-fold--1) to prevent a softer titanium lock-bar from wearing more quickly than the harder steel tang/interface of the blade, and 2) to minimize or eliminate the lock-stick that frequently occurs between dis-similar materials, i.e. titanium and steel, and is exacerbated by the presence of lubricants.
>Steel inserts are certainly popular and, while one might debate their usefulness/function, there is no question that marketing the feature du jour is an effective way to sell knives. Not saying that's a bad thing, either, just sayin'.
>I've wondered about this "early lock-up" thing--another popular concept. I've always assumed that those who thought that a good thing were thinking about eventual wear and longevity. Those that were thinking, anyway. I've looked at some knives whose "early lock-up" has been touted in ads or sales threads and have been concerned that there is so little engagement there as to be dangerous.
>In his post above, tiguy, who is an engineer, gives an excellent description of what the carbidizing process is and what its applications are. As carbidizing is intended to add a hardened (harder) layer to a substrate and inasmuch as carbides are the particles in steel blades that do the cutting, I wonder if the effect of carbidizing a lock-bar is sorta like robbing Peter to pay Paul (or rather enriching Paul to the eventual impoverishment of Peter). Do we harden the lock-bar only to wear away the blade tang? I had thought that carbidizing lock-bars, as demonstrated on several Youtube videos, was more a method to cure lock-rock or poor lock-up in ill-performing knives.
>I had thought that CRK's process for treating the titanium lock-bar was not carbidizing but is carburizing, which is essentially heat-treatment to harden the lock-bar. Tiguy can help with the definition. I recall seeing somewhere in CRK literature that their process included heating up the end of the lock-bar with a torch, but my old filing cabinet of a memory is quite full and some things are surely mis-filed.
>Anarchy's pic of his Hati's lock-bar shoulder had me scrambling for a flashlight to check my two liner lock Shiros (F3 and 111) to see if they had that feature. My newest Shiro is an Axis-lock Tabargan and thankfully exempt from this discussion. The two former do not have shoulders, though they do have steel inserts. While the shoulder will prevent locking over-travel (as opposed to the more well-known disengagement over-travel stop), I wonder what might happen if enough wear occurs to engage the shoulder to the point that the lock-bar develops rock or play and is prevented from further engagement. Is the shoulder therefore a sort of early-warning system?
>Finally, on the subject of lock-bars wearing out, I recall something that Ann Reeve wrote to the effect that lock-bar engagement over-travel is only an issue when the lockbar hits the blade. When that happens, send it in. The only knife I have that's developed any major change in engagement travel is the Sebenza 25 that I bought here last July, and that knife uses the ceramic ball interface. That one has moved from about 50-60% lock-up to around 75-80%, but that also occurred after considerable tinkering with centering (adjustable pivot), washer polishing, and a change in lubrication. Where that change may be some cause for concern, it's not near touching, and if it does I'll just do what Ann says and send it in. I like that all my CRK lockbars fully engage with the blade ramps and are not hanging half-or-more off like several of my other knifes. Just seems more solid to me.
Anyway, like I said, just a whole bunch of random thoughts and observations above. Either food for thought or food to be left on one's plate. Also, I'll go back and proof-read as is my custom, but as someone once said "Auto-correct is my enema" especially when it comes to carbidizing, carbonizing, carburizing, and any compound word with lock in it.
