Woodskevin Posted December 30, 2011 Share Posted December 30, 2011 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? Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted December 30, 2011 Share Posted December 30, 2011 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. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 30, 2011 Share Posted December 30, 2011 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. Quote Link to comment Share on other sites More sharing options...
Woodskevin Posted December 30, 2011 Author Share Posted December 30, 2011 It bent in use. I wasn't sure if it would break bending it cold. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted December 30, 2011 Share Posted December 30, 2011 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 Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted December 30, 2011 Share Posted December 30, 2011 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 Quote Link to comment Share on other sites More sharing options...
Woodskevin Posted December 30, 2011 Author Share Posted December 30, 2011 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. Quote Link to comment Share on other sites More sharing options...
Woodskevin Posted December 30, 2011 Author Share Posted December 30, 2011 Thanks Swedefiddle. Its not a bad bend so I'll straighten it cold and pray for the best. Quote Link to comment Share on other sites More sharing options...
basher Posted January 1, 2012 Share Posted January 1, 2012 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..... Quote Link to comment Share on other sites More sharing options...
Marksnagel Posted January 2, 2012 Share Posted January 2, 2012 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. Quote Link to comment Share on other sites More sharing options...
Woodskevin Posted January 2, 2012 Author Share Posted January 2, 2012 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. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 3, 2012 Share Posted January 3, 2012 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! Quote Link to comment Share on other sites More sharing options...
Woodskevin Posted January 4, 2012 Author Share Posted January 4, 2012 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. Quote Link to comment Share on other sites More sharing options...
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