Tooo Thick

Joined
Jul 3, 2002
Messages
645
I was worried about warping. So, I left the blades pretty darn thick. They were D2 hardened to 60.

For .180 (3/16ths) steel I ground to an edge thickness of .060, then treated. Well now that they are hardened, I'm wearing out belts trying to get the flat grind down to .030. (Personally I like sharpening knives with an edge around .020 thick.) I've finished one, I have another down to .045, but I don't think I can stand trying to get the third one down to size.

(In the future I hope I don't need to leave this much meat before heat treating.)

Any Ideas how I can get these down to size? Maybe buy a coarse diamond hone and do it by hand? Maybe switch to convex and just work the edge?

Ideas?

Steve

PS I'm using up Zirconia 60 grit belts.
 
Why are you hardening at such thicknesses?

Cause I don't know any better. It's a goof.

Actually I've never been able to find out how thin I can go. I've asked around, but never got a measurable answer. About all I can gather is if it is too thin it warps, because the metal cools at different rates between the thick and thin parts. But, that doesn't tell me how far I can go. Not even the guys at the heat treating place will give me an answer I can use. I'm sure it's complicated because of all the factors (Thickest part to thinest, how gradual is the change, type of steel, hardening methods used, ....). So, maybe there isn't an answer.

Chalk it up to being tooo worried.

The current problem is what do I do now?

Steve
 
I did the same thing with a couple of ATS34 hunters, not quite as hard to grind but I was using a 4X36 and couldn't find any decent belts. One ended up convex, the other got flat ground. I can't decide which one I like better now, both cut really well. The convex was a bear to sharpen the first time though.
If you try to convex them, make sure you still thin more than just the very edge. I started to do that and wasn't very happy with the results, it didn't cut very well because it was too wedge shaped.

D2 is air hardening right? I think you could go pretty thin, since the quenching process isn't nearly as harsh as an oil or water quench. I've been grinding O1 down to .050-.040 before HT with an oil quench, .040 ought to be safe for D2? Anyone want to chime in that knows what their talkin about?
 
I've done a couple O1 (oil quench) at about .025 with no problem. I've done a couple ATS-34 (air quench), one at .040 and one at .020. No problem with them either. I'll go with .020 from here on until something bad happens. .060! I feel your pain.

Roger
 
Decimals don't carry any meaning for me, I grind to about 3/64ths before HT, which is probably about like what Roger's doing.

Dave
 
Oops, just checked and I've really been going closer to .030 , with no problems. If you like to sharpen at .020 than you can probably go to .020 or .025 and then you'd only have to grind the scale off after heat treat.

3/64 = .046
 
Thanks Guys,

But what do I do with this blank at .060" (1/16") edge thickness?

I don't want to throw it away. I have hours invested. And I don't want to try and anneal an air hardened steel and pay to have it re-hardened.

Steve
 
I'd say your only choice is to keep grinding. You can save a little time by convex grinding it, just don't try to take it all off at the very edge. I would try to remove material about halfway up the blade.

You'll get there eventually. I think I had about 6 hours each in the two hunters I goofed up on. They went from being spare time project knives, to find something else I have to do so I can stay away from the grinder knives. But I got them done eventually.
 
make one pass on the grinder, dunk, wipe, and i only wipe the side i am grinding. you want to use 100-120 grit ceramic belts try calling www.trugrit.com and ask scott if the have or can get 2x48" ceramic belts norton, or 3m they will cost more but in the long run less since they will last at least three times longer. good luck.
 
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