Can I Re-Temper, And How?

[mgbruch]

So... I recently lost my home and shop to a forest fire in Northeastern, WA.  My temporary home does afford me with a workbench, and place to work; so I'm beginning to refit... I guess you would say.

In going through the debris I was able to salvage several of my chisels.  They look good to me when cleaned up a little, but they have lost their temper.  I've tempered a lot of smaller springs, but I'm assuming that my chisels will require a different temper.  The tools I'll have to do this are; a propane torch, a Maap torch, and water or oil for quenching.

I found some information on tempering; but it was in terms of temperature.  And I'll need information in terms of color.  So, how do I re-temper my chisels?

Many Thanks

Mike

[Long Ears]

Basically they are annealed being they cooled slowly after the fire. They are carbon steel I would think. I would heat them bright red or to nonmagnetic and quench in canola oil sharp end first. Don't drop them they are brittle hard now. Clean them to bright getting all the scale removed. Now put them in your kitchen oven at 450 degrees for 1 hour. Turn off the oven and let them cool slowly in the oven. I do this a 2nd time but some guys don't. I would think they will be good as new. There will be several guys chine in I'm sure. So sorry for your loss. If you need something I can help with let me know. Bob

[rich pierce]

Oops Bob said the same thing while I was posting.

My process
Step 1 is hardening. Heat up the chisel to what looks orange to me at least, heating the last inch or two at most towards the edge. Quench in warmed canola oil or other vegetable oil. Maybe there’s a diner they might give you some old oil from making fried foods. Clean your heated and quenched chisels and check for hardness. If hard, rub off all scale till bright. In moderate indirect light, heat a chisel from the middle toward the edge, waving the torch and turning it. Get the edge to purple carefully and slowly. If it’s going to blue you’d better quench it. Alternatively heat them in a tray of dry sand in the oven, laying them on sand and coveting with sand to 450-500 degrees for an hour and let cool.

[P.W.Berkuta]

Sorry to hear of your sad loss. To start with how about using the correct terminology for what you want to do. FIRST you have to harden those items THEN you can temper them to achieve the correct hardness and ductility from the tempering process. It is best if you know what kind of carbon steel you have. I would suggest following Long Ears post. Good luck.

[Bob Roller]

Longears gets my vote on the chisels.You KNOW what happened to your tools which is "better"than a robbery and you will restore them.


Bob Roller

[Rmjchas]

these are the oxide colors from reheating (tempering) after annealing with suggestions on how hard to leave the steel.

[Dphariss]

I would draw the handle ends to blue. The rest can be the 450-500 range. Making them too hard all the way back to the handle can cause breakage. Only the cutting edge on the knife needs to be hard. Blue will bring it to spring and it will stand more abuse this way.