how to spot anneal ?

I hardened my bolsters before drilling a relief spot for the pivot screw. Now I need to drill out a 3/16 hole approx 3/32 depth into the back of the bolster after hardening. Any sugestions? The material is high carbon damascus.
Thanks
Steve

Take an old drill bit and chuck it upside down in a drill press. Make sure the bottom is flat. Put your drill press to the fastest speed it can go. Put the metal you want to spot anneal under the drill and press down while running at full speed. You will need to clamp it. Press fairly hard to create friction and heat things up. It doesn't take that long to get pretty hot in that spot and soften it up. The drill bit is ruined but you get to save the blade. I've had to do this a couple times. Now I just use a carbide drill but if you don't have one in the size you need, I know this process works.

I assume this is in answer to something completely unrelated.

it appears to be the best answer in the thread so far! :biggrin:

small butane powered pencil torches are surprisingly quite effective of spot annealing

Hey I really like that upside down bit method, I will try to remember it.

SVanderkolff said:

I assume this is in answer to something completely unrelated.

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sorry guys I banned the guy that post before this posted. it was spam....

Just remember that if you have a spot on the bolsters that is annealed if you plan on etching the bolsters the spot will etch at a different rate to the hardened steel

A solid carbide drill bit would probably work but you have to order one. As a solitude try a carbide masonry bit. Clamp, drill slowly and use water or coolant.