Tempering steel

[Brent Cutshall]

Well people, I think I'm going to attempt to make a moulding plane from scratch. Would anyone know what steel I should use and what difference does it make from regular steel from Lowes or Home Depot. Most importantly I would like to know if I should temper it and if so, how.

[george wilson]

The only steels sold at Lowe's or a hardware store are MILD steels that have no ability to harden at all.

You must Google Enco on the internet,and order some 01 precision ground tool steel. It usually comes in 18" lengths,but can be had in 36" length too. It comes "soft"(annealed),and can be hacksawed and filed or ground into the shape you want.

01 CAN suddenly harden if you file it too vigorously. It will only harden a few thousandths deep,but will leave a nasty scratch on your file. So,file deliberately,but not as fast as you can. I have had this happen. You have to grind away the hard spot and resume filing.

If you do not have a forge or knife maker's furnace,a weed burner will get the steel plenty hot enough to harden. Failing that,make some bricks into a "corner" shaped alcove to lay the finished cutter in. This will allow you to get a couple of inches of the cutting end to an ORANGE color. You only need to harden the cutting end of the blade. The "tail" is always left soft anyway. Quench the cutter in at least a pint of vegetable oil. DO NOT use OLD motor oil. It will deposit a thick,hard as blazes coating of black carbon on your blade. The devil to remove. After you have tested the hardened iron with a sharp file(it should just skate off),sand away the dark surface of the metal near the cutting edge,and slowly heat the cutting end to a dark brown or even a purple color. Try NOT to let the color rise up to a blue color,which is a bit soft for a plane iron. If this happens,you have to harden it all over again and re temper. Try not to have to do this more than once because the steel will get out of control molecularly and fail to heat treat properly.

It is really MUCH BETTER if you do NOT put the bevel on the plane blade before you heat treat it,because the blade is almost certain to bow into a little curve across its width. You can only grind the steel after heat treating though,so if it is a complex shaped molding you might have to live with the curve. If the iron is not very wide,the curve will be too small to matter.

[Bob Glenn]

What he said!