Question for Cliff Stamp, and possibly others

Ben Dover

Ben Dover

Joined
Aug 2, 2006
Messages
2,809
I've read a lot here about belt sanders, especially the $30 Harbor freight model. They seem VERY enticing.

For a person who has never used one, is it possible to be careful enough to reprofile expensive, high quality blades without the risk of overheating and ruining the temper?

I'm think of 1095 very well hardened, A-2 and D-2.

I can reprofile HC420 and the 440A & B series easily enough with my coarse Diasharp, but I have had a real bitch of a time with well heat treated 1095, and D-2 has me pulling my hair out. (:D what little there is left of it
!:D

I would like a way to reprofile, and possibly resharpen, these blades MUCh quicker, but i've read so many warnings about grindng wheels ruining blades, and I've wonderd if sanders might not be just as bad.

Is there some special technique for keeping the blade cool, or does that require a special, high dollar sander with flowing water.

Thanks in advance,

Ben
 
As Bill Siegle advised me when I was undertaking a blade fix, use new belts, cool often (I had a bucket of water close to the sander), and use very light pressure.

I only use mine for blade fixes or big reprofiles.
 
Grinding/sanding create heat.The job can be done with a little patience.Frequent cooling in a can of water is the answer. Avoid temperatures above what might be the tempering temperature ~ 400 F.
 
Ben Dover said:
For a person who has never used one, is it possible to be careful enough to reprofile expensive, high quality blades without the risk of overheating and ruining the temper?
Click to expand...

There will always be risk, but you can reduce it to an insignificant amount.

I can reprofile HC420 and the 440A & B series easily enough with my coarse Diasharp, but I have had a real bitch of a time with well heat treated 1095, and D-2 has me pulling my hair out.
Click to expand...

D2 does that to everyone, it has a very low grindability. The high vanadium CPM steels are similar, some are even worse. 10V makes D2 look like 420HC.

I would like a way to reprofile, and possibly resharpen, these blades MUCh quicker ...
Click to expand...

Generally sharpening isn't an issue, it doesn't matter the steel. You shape the edge at the minimal angle which keeps it from deforming and then micro-bevel at the desired finish, which just means to raise the angle slightly. This will create a very tiny bevel, less than 0.1 mm wide and since so little metal needs to be removed it will grind quickly even on D2 and similar steels. You create the relief on the belt sander, you generally only have to do this once unless you really damage the knife.

Is there some special technique for keeping the blade cool ...
Click to expand...

Keep your fingers very close to the edge, you will get uncomfortable long before the blade will. What you want to avoid is exceeding the tempering temperature of the blade. The lowest temper for blades is about 212 F (boiling water) and you won't tolerate close to that. As the blade heats up past your comfort zone, cool it in water. In general, most knives are so thick you can grind them multiple times before they need to be cooled.

If you are grinding very thin blades, edges less than ten degrees per side and <0.010" thick, they can overheat rapidly because there is little metal around the edge to soak up the heat. If you notice the heat building up so fast that you can't even make one pass before it gets uncomfortable then you have to press lighter and/or use better belts. However there are few if any production knives like that and you need to have really extreme viewpoints to be grinding that on a belt sander anyway.

-Cliff
 
Cliff, (and everyone else that responded)

Thank you very much for the info. I do appreciate it!:)
 
Broos said:
As Bill Siegle advised me when I was undertaking a blade fix, use new belts, cool often (I had a bucket of water close to the sander), and use very light pressure.
Click to expand...
That about sums it up.
Scott
 
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