Just a question.
The blank you are using, hardened already?
If not, do not go too thin on the edge. Warpage a real danger.
Nope not hardened yet, and I have left about 0.7mm on the edge, I am aware of warping during the hardening.
On my previous utility knife I left about 1mm before hardening and it took me a ton of work to get the last edge done.
I still want to make a little soup can furnace but with the lockdown I need some refractory cement.
On the utility I struggled to get the blade to non magnetic with only my MAPP torch. I had to use my gas camping stove from the bottom and the MAPP from the top.
You can mix silica san or really clean river sand, 50/50 with plaster o Paris to make a type of refractory cement. It won't last long, but it is cheap and can be easily replaced. You can get Plaster of Paris from your pharmacy, which will be open - just get some Panado's at the same time

I'm not sure what steel that is that you got from KMTS, but beware that to heat treat stainless steel is not as simple as high carbon steel. Your temperature needs to be very accurate, and the temp is dependant on the type of steel. Also, when heat treating SS, the blade must be sealed in a heavy duty foil, as it does not like oxygen.
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