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Annealing
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Well, I had an old file...really old, not the brittle steel of the new ones and I thought it would be a nice blade for something. I annealed it in my wood burning furnace (kachelofen) last night. This morning it was warped. What's the best way to straighten it? Should I reheat it?

Thanks

The chef
 
Posts: 2763 | Registered: 11 March 2004Reply With Quote
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Just lay it on a block of wood and straighten it with a hammer. You can do it before you grind the teeth off so you don't leave marks.


for every hour in front of the computer you should have 3 hours outside
 
Posts: 7680 | Location: Between 2 rivers, Middle USA | Registered: 19 August 2000Reply With Quote
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Then how would you temper it when shaped.Drop-Shot
 
Posts: 91 | Location: Helena,Montana | Registered: 26 December 2005Reply With Quote
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Drop shot, you heat it to cherry red and quench it in oil this hardens it. Then you temper it with mild heat.
 
Posts: 2763 | Registered: 11 March 2004Reply With Quote
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Got it CalgaryChef,thanks for the help.Drop-Shot
 
Posts: 91 | Location: Helena,Montana | Registered: 26 December 2005Reply With Quote
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If the piece is warped it could indicate uneven cooling. Uneven cooling may indicate it is not fully annealed.

Typically annealing is done by taking the material above the critical temperature where it becomes non-magnetic, then cooling very slowly.

Fine, fresh ash or vermiculite are good media for cooling material to be annealed. You can buy vermiculite at the local garden center.

If you are forging the blade there would have been no need to anneal it before working. But you should do a grain refining step when the hammering is done. Heat the material to above critical temp and quench in warm oil or oil mixed with ATF. Heat again to a slightly lower temp and quench. Heat again to a slightly lower temp and quench.

This will give you a fine partical size in the material. This will result in a much stronger blade when full hardening and tempering is done.

To harden when the blade is close to its final shape, take it to above critical temp and quench it in oil/ATF. Plunge the blade vertically into the mix and dunk it up and down. Remember that the oil pool can take only so many added calories until it boils and catches fire, so use enough oil and work slowly enough that the pool's heat capacity is not exceeded.

When the blade is cool, you want to heat the back edge of the blade until the straw line just reaches the edge. This will make the body of the blade softer while leaving the edge hard.

All of this stakes some skill. Even when you have the mechanics down, the result may not be as consistent as you might believe. To get great consistency as measured by a good hardness tester takes real skill and experience.

Regardless, it is great fun and worth doing a couple of times because it gives you a much greater appreciation of a fine knife!

(Beware that heating steel and banging on it can be addictive and as a result not cheap!)


Mike

--------------
DRSS, Womper's Club, NRA Life Member/Charter Member NRA Golden Eagles ...
Knifemaker, http://www.mstarling.com
 
Posts: 6199 | Location: Charleston, WV | Registered: 31 August 2002Reply With Quote
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Mike, I haven't seen you poting lately. Nice to see you around. Thanks for the informative post. I'm thinking about making a small propane burning "crucible" to heat my blade in. I've got some fireclay laying around and I know how to use it. Have you seen the type where it's a vertical cylinder with a hole down the middle and you put a propane torch into a side hole. I've got a turbo torch that burns propane or a hotter gas mix. I saw one somewhere on the net and it looks ok for a few simple blades, but like everything on the net an impartial opinion is good.

thanks

the chef
 
Posts: 2763 | Registered: 11 March 2004Reply With Quote
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