knife edge width

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Nov 8, 2018
6
0
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south yorkshire
hello gents could anyone help me please by telling me how wide to leave the edge of a knife blade so it doesn't crack with the heat treatment process.
many thanks in advance john
 

Robson Valley

Full Member
Nov 24, 2014
9,959
2,664
McBride, BC
I make my own wood carving tools from two blade sources:
1. A farrier's hoof trimming crooked knive needs to be quite tough. All of mine (20?) are 3/32" = 2.3 mm.
2. The double edged Pacific Northwest wood carving knives (8?) are all 3/32" as well.
 

Broch

Life Member
Jan 18, 2009
7,983
7,759
Mid Wales
www.mont-hmg.co.uk
I know I think a bit differently to the more prolific 'makers' on here but I don't think I've ever had an edge crack in heat treatment.

I like to do as little work on the blade as possible after it's been tempered especially no belt or wheel grinding. Between 200 and 400 Degrees C you will achieve between 60RC and 50 RC when tempering on 01 tool steel. If you use any kind of belt or wheel on the blade after tempering you can easily reach those temperatures (unless you're running in water) especially on the very thin edge and completely ruin the hardness originally aimed for.

If your heat treatment is controlled (I use a small kiln) so the temperature cannot exceed the hardening temperature even on the thin edge you shouldn't get cracking when quenched and so can take the edge down to near sharp. Then, after tempering, you only need light work, without the risk of further tempering, to get the final blade edge. Well, that's my experience anyway - others may tell you differently.
 
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