Had to redo a whole batch of hinges after a bad heat treat last month

I was working on a set of 12 strap hinges for a barn door project, and I rushed the tempering cycle on my Evenheat oven. Set it to 400 degrees but only left them in for about 20 minutes. Every single one came out way too brittle and snapped at the pin hole during a test fit. Had to scrap all the 1/4 inch stock and start over from scratch. Anyone have a good rule of thumb for tempering time on mild steel that thick?

3 comments

3 Comments

noahhall3mo ago

Been there, ruined a whole batch of chisels the same way.

angela403mo ago

Switched to using a cheap, sacrificial piece of wood as a backing board after that. It saves the edge from hitting the concrete floor when you punch through. A piece of scrap plywood is basically a permanent fixture on my bench now. Still stings to remember the sound of those chisel tips going dull all at once.

john_murphy15d ago

Man, I gotta disagree with you there. That sacrificial board thing always felt like a crutch to me. I just got in the habit of backing off the pressure right before the chisel punches through. That way you don't need any extra wood cluttering up your bench. Learned that trick years ago and never looked back. Once you get the feel for it, you can stop exactly at the right moment every time.