I have a friend who has asked me to straighten his machete. It's bowed in a mild s shape. What would you suggest the hardening and tempering process to be?

Are you asking:
- how to harden and temper as a generality
or
- the temperatures to use when the alloy is not known?

The short answer is to heat to above non-magnetic, quench in the appropriate medium for the type of steel, then soak repeatedly at the appropriate temperature for that type of steel.
If the machete is a flea-market special, then you might be able to straighten it by whacking it with a wooden mallet. But since the metal is unknown, providing a more appropriate and liability-safe answer is to say the least difficult. If you harden and temper it, and it breaks off and flies into his face, guess who is likely to be liable.

Disclaimer: I am not a lawyer and don't pretend to be one.

Did it get bent in use or in heat treat?

If in use you can probably straighten it cold with less likelihood of damage

If in heat treat---well you're making a guess as to alloy and heat treat process---good luck.

It bent in use. I wasn't sure if it would break bending it cold.

It bent in use. I wasn't sure if it would break bending it cold.

Well, it didn't break the first time! (haha, not helpful)

I was asked to straighten a machete made from a bucksaw. I heated it, straightened it, normalized it as practice for heating such a long object, and then heated to non-magnetic along its entire length (easier said than done) and quenched in water, then tempered with a propane torch to dark straw straw or purple on the edge and blue-gray on the spine (about 1/3 the width). The owner is pleased, and aware of the risks.

Forgot to mention the furniture was removed prior to the owner giving the blade to me.

Phil

Good Morning,

A trick that Arnon (in Portland) showed, was a hammer he made with a piece of rock drill with the carbide bit in place. he would use the carbide hammer to straighten a knife/blade that bent after heat treating. A twist would be taken out by working the blade sideways, a bend would be taken out lengthways. Gentle tapping changes one side of the blade and doesn't upset the blade to refinish.

If the machete bent in use, it will straighten cold. This is the same as bent garden fork tines, straighten cold. If it breaks, it was junk anyway.

Happy New Year,
Neil

Thanks Phil. I was thinking of straightening, normalizing, hardening, then temper it using a large block of metal and running it back and forth till the colors run.

Thanks Swedefiddle. Its not a bad bend so I'll straighten it cold and pray for the best.

the middle way would be to try straitening at a tempering temp I would go for around 200c . the material at this temp is much less springy and easier to bend true (and less likly to break) 200c is also not so high as to screw the blades previous temper.
this way means a lot less aggro as well . of course the fact that it bent in the first place is probably a sign of incomplete hardening.....

A thought I have is, what is the quality of the blade. My son bought one from a big box store and it bends when you look at it sideways. Sad piece of steel. It may not be worth the time and effort.
I believe his was sold under Ozark Mountain which sells a lot of outdoor camping equipment for a low price to be used by the common person.

A thought I have is, what is the quality of the blade. My son bought one from a big box store and it bends when you look at it sideways. Sad piece of steel. It may not be worth the time and effort.
I believe his was sold under Ozark Mountain which sells a lot of outdoor camping equipment for a low price to be used by the common person.

This one I'm working on is a Trimontina. Heres what their website said. Blade Composition: SAE 1070 High-Carbon Steel. I'm gonna go with JPH's recommendations in "The Complete Bladesmith" and straighten, harden, and heat treat it again.

I assume you don't have a lot of experience with bladesmithing as you are asking about it. You may put more bends in with re-heat treating it! Good Luck!

I assume you don't have a lot of experience with bladesmithing as you are asking about it. You may put more bends in with re-heat treating it! Good Luck!

Very true and very possible. If I fail I'll just buy him another one. It's a friendly challenge, not a paying customer.