Hand Tools

Re: First Smashed Marking Knife *PIC*

William Duffield
I got my soft refractory fire bricks from Sheffield Pottery.


I need to reduce the size of my file photos of my furnace and the process I used to build it, but in the meantime, I have some pics of a heat treating furnace that Bob in NJ built from my descriptions.

The big hole is easily drilled in the bricks with a hole saw (e.g., one used for installing lock sets in doors), and the small hole for the torch nozzle with a spade bit. Clamp two bricks together, drill as deep as you can with the hole saw. Take the bricks apart, and knock out the half cores with a cold chisel. Clamp them back together and drill the hole deeper. Repeat until it is deep enough to enclose your blades.

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