thin hollow grinding after heat treatment

C

Cliff Stamp

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Anyone with experience with hollow grinding thin blades after heat treatment. My main concern is overheating due to the very small amount of metal and thus a vastly reduced heat sink. By thin I mean blades that are 0.005-0.010" thick, ~1/4" back from the edge. To grind this thin do you need something really slow like a Tormek wet wheel grinder. There are much cheaper slow wet wheel grinders available, but not as slow as the Tormek.

-Cliff
 
I would say a variable speed grinder at very slow speed.

The thickness.005, is not much thicker than a human hair, and there is a real possibility of either grinding right through, or burning a patch of steel, which would cause warping in that area. It only takes a second.

Maybe your best bet WOULD be a wet grinder.:eek:
 
Yes, the possiblity of going right through is one of the main concerns, first off though getting a constant and smooth bevel would be the biggest problem I would imagine. I can get a wet grinder locally, ~70 RPM on a large wheel, ~10" .

-Cliff
 
Cliff,
I grind almost everything after heat treatment. Using good, sharp belts, working barehanded, and finishing with wet diamond belts, I've never worried about getting the steel too hot.
I don't grind blades down that thin. .016 - .020 at the edge and the right bevel works for me. The last straight razor I built was about 20 years ago and it was very thin. :)
If you grind the blade before heat treat you still have to leave enough material for final cleanup. That's the stage where the most heat occurs.
 
0.005-0.010" thick:eek: cliff can I ask what the blade
or blades are going to be used for?
at 1/4" back from the edge are you going to grind to the edge with no edge bevel?
Ouch,,, just thinking about it My fingers hurt:)
 
I agree with Kit.. If you use bare hands(so you feel the heat), dunk it often, and use sharp ceramic belts you shouldnt develop too much heat, at least not enough to screw it up... Even grinding to dead zero in hardened state can be done, if you take your time, and use nice new belts..
 
Graymaker :

...can I ask what the blade or blades are going to be used for?
Click to expand...

It is a light utility knife. Carpet, insulation, ropes, fabrics, cardboard, foods, woods and other such soft materials. The first few blades made will likely be damaged in use as I fill out the scope of work and see just how far the knife can be used without damage.

Steel is a critical point here, the ideal steel for this is HSS at full hardness. Starting off though I'll probably just grind cheaper knives until I can do a decent bevel the likely modify a few customs which have thickened edges from repeated sharpening.

are you going to grind to the edge with no edge bevel?
Click to expand...

Sharpened flat to the stone with the shoulder of the hollow grind forming the angle, so the edge should be ~5 degrees per side. The grind profile should like something like this :

http://www.panix.com/~alvinj/HSSknife.jpg

Thanks for the confirmation Kit and Trace.

-Cliff
 
Thanks Cliff
they would be great for cutting deer steaks up all right
I Agree,, Steel would be a critical point.
a HIgh Carbon steel like O1, griding that thin would be a fun trip..
to much fun for me :)
I'd like to know how they turn out.if you would Cliff.:)
 
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