Lock bar Spalling?

flipe8

flipe8

Joined
Oct 24, 2005
Messages
2,823
For the past few days now, my Seb has become increasingly more difficult to disengage. I tried the pencil trick and took the knife apart to clean with no luck. It is very sticky, almost gritty in disengaging. I know it's not a bad thing that the lock is difficult to unlock, but it has me wondering if this sort of change in action would be considered normal? Any thoughts?
Thanks
Edit: the term "spalling"I was using occurs to concrete during fire exposure:o I though it crossed over to the heat-treated area of the lockbar as well...
 
I have experienced that a few times, in every instance except one a thorough cleaning/disassembly fixed it. In one instance I sent it back to CRK and they fixed it.
 
Thanks guys. I'll take it apart, give a good cleaning and see how it goes.
 
I think the term you're looking for is Galling, from Wikipedia;

Galling is a cold welding phenomenon which can occur when uncoated stainless steel or aluminium alloy parts, such as the threads of nuts and bolts, are forced together. These materials owe their corrosion resistance to the ease with which they passivate, forming a thin protective oxide layer. The friction scrapes off this oxide layer from the surface asperities and exposes clean reactive metal. If the mating parts are of a sufficiently similar material, no additional activation energy is needed to cold weld them together.

Galling can occur even if the parts are brought together slowly, and it is prevented by the presence of grease or surface coatings, even if the surface coatings increase friction. It does not occur when joining dissimilar materials (for example threading 18-8 stainless into 17-4 stainless) even though both of those materials are susceptible to galling. Galling does not occur on carbon steel.

In metalworking that involves cutting (primarily turning and milling) "galling" is used to describe a phenomenon which often occurs when cutting soft metal: workpiece material sticking to the cutter. It often occurs with aluminum and is a common cause of tool breakdown. When a soft material sticks to the cutting edges the effective surface area of the cutter increases. To achieve the pressure needed to cut the workpiece, a greater force is needed often resulting in extensive wear or breakage of the cutting tool.
Click to expand...

I've also remember reading that sometimes the lock bar wasn't 'heat treated' enough to
prevent the galling to occur, perhaps someone from CRK will chime in regarding this.
G2
 
Spalling is a common mode of failure found in bearings and is actually a fatigue failure.This begins under the surface....Galling is ,as Gary mentions ,cold welding. Softer metals are more prone to galling....I'm not sure you have either. Take it apart , thoroughly,clean, lube and assemble.
 
Thanks guys. It looks like a flake has come off where the lock bar is heat-treated. It's quite small, smaller than the ball detent, but it's there for sure. It doesn't appear to be a big issue, but I'll be watching it and I'll consider sending it in should the flake become larger.
 
You can try these two things:
1. Give your sebenza a good flick opening.
2. If you are may be using oil instead of grease this can cause sticking. Wipe the oil from the blade tang.
 
Here is an older thread where CRK chimed in about this problem;

Click on this Link to view it.

G2
 
I bought a brand new large Classic rosewood that had the lock sticky right out of the box. It would hang up when you tried to release it and would then break free with a pop. Rather than send it to CRK I took it apart to inspect it. I couldn't see anything with the naked eye but using a 10X loupe I could see a very small burr on the lock bar. One light pass with a fine stone and it was gone and the knife remained trouble free.
 
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