How do you re-temper a chisel ?

Answer 1

There is no reason to retemper the chisel. It was tempered when it was made and trying to do so again will either ruin the steel in it because you get it too hot or it will get brittle and the cutting edge will break every time you try to use it.
Different metals reguire a certain Temp., when doing this and there is no way for you or anyone else to look at it and tell you wheather you should get it a soft orange hot, a deep red hot or even a white hot before the oil dredgeing.
If you aer determined to do it anyway, I will walk out on the plank and say use a torch and get the end of it a soft orange collor and then just dip the last 1/4" in oil and hold it there for several minutes and then plunge the rest of it in there until cooled.

They are made of many different types of alloy and it is more than likely as hard as the steel will stand already.
It should only need a good sharpening.
I would bet you ten to one that if you try you will ruin it, not being a smarty pants, but knowing what I am saying is true.

Answer 2

Hardening and Tempering are two different techniques. When you over heat a chisel while grinding it what you are doing is taking the temper too far to the soft end of the scale. To correct this you must harden the steel, then temper it to the desired level. Hardening must be done in the semi-darkness in a coal or charcoal fire that has burned down to the point that there is no visible flame. place the chisel in the hot coals and heat it to cherry red, the simplest way to tell is when the color of the steel matches the color of the coals. The technical way to tell is when the color stops changing after it hits a red glow. Once you are satisfied that it is at cherry red dip it in the liquid of your choice, tepid water, tepid salt water (brine), or oil (used motor oil or traditionally, rendered sheeps fat). If you use oil you probably wont need to go any further, it will be hard enough to hold an edge, but soft enough to not shatter. If you use brine or water you will need to temper (soften) the steel. To temper the steel you must bring it to a polish then hold it over, not in a flame. As it warms up you will start seeing bands of color move through the steel, when the correct color just reaches the tip of the chisel, quench again, briefly to stop further tempering of the edge. Some ovens get to the right temp to apply the temper that you want. If yours does you can simply place the hardened chisel in the oven, set it for that temp then let the chisel heat up then let the oven cool down with the chisel inside.

Answer 3

Heat evenly with a torch until red hot, then quench in oil bath.

Answer 4

Heat it up with a torch, and then when redhot, dip it in an oil bath

Answer 5

Cheaper just to buy a new one.

Answer 6

I would take it to a pro to fix it.

Answer 7

You would need a forge.