making a knife out of band saw blades

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vlapenta

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Jan 13, 2008
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I have been making some knife blanks out of thin bandsaw blades as in a wood smith ,they are 1inch wide and 60 thousand thick .
get them red hot ,let them cool overnite in wood ashes and temper red then quench .,bake at 350 for 1 hr ,let cool room temp and they brake like glass ....any help??? ps useing a magnet for temper non stick
 
Have any idea of the alloy? You need to temper at a higher temp probably closer to 450 but someone will have better info.
 
consider not anealing them. just grind them hard they are not that thick so it shouldnt be too bad
 
It's not clear from your post whether your process is an attempt to heat treat after you have shaped them, and you are unhappy with the heat treat result, or whether you are trying to make them soft enough to shape before re-heat treating.

Guessing you are trying to make them soft enough to work, here are some thoughts:

"let them cool overnite in wood ashes and temper red then quench"

If you are trying to get them soft enough to grind, consider JUST annealing them - heat up and cool slowly. Annealing and then re-hardening doesn't make a lot of sense unless there's a reason you haven't shared.

There's a bit of information on annealing out there - for example, here is a great thread on O-1



Why are you using bandsaw blades? Can you find out what kind of steel they are? Some are made of multiple layers of different metal and might not be a great choice for home heat treating.
 
Good advice above- try tempering higher, for longer. If you are indeed merely trying to soften them, anneal by cooling slowly from non-magnetic. It also strikes me that you did not mention what you are quenching in. If you're water quenching such thin tool steel, there is a good chance that you are shocking it into a micro-cracked structure, which then becomes apparent as soon as you try to do anything with them. Use oil if you are not already.
As stated above, annealing and re-hardening does not usually make a lot of sense- unless you are trying to normalize the steel for better results in the quench. Usually you would do this by heating the steel to critical and letting it air cool- I have noticed however, that often very thin carbon steels will significantly air-harden when trying to normalize. The answer sometimes may be to anneal (cool slower than air.)
One thing that scrap bandsaw blade is good for is learning to pattern weld. It's nice and thin, try alternating it with pallet strapping of a similar width.
 
It's possible that blade could be bimetal, which introduces a whole world of challenges. You could be dealing with anything from 15n20 to M42 or a mix of both. Recycled steel is kind of an advanced project, but it gets much easier if the manufacturer will ID it for you.

If you have to use 'best guess" then raise the tempering temperature a bit at a time till the edge will flex without chipping.

If it's bimetal, you'll need to choose which metal you want for the edge and which for the spine....

Rob!
 
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