Dustin Stephens

My question is what do i need to do to it before i attemp to turn them into knives?  What steel is it?  Whats the best way to temper and such?  I plan on forging some and stock removal on some as well.

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Anthony San Miguel
Do you know what they came off of? So many possibilities as to what type of steel they are. Forge them to as close to shape as you possibly can. Then, I would try to anneal them by heating the stock past critical, then a very slow cool. I use a steel can with a lid filled with vermiculite to slow the cooling rate. At this point the steel should be as soft as you can get it. Do your grinding, filing and drilling.

I would do at least two normalizing cycles next to relieve the stress in the stock and reduce the grain size that no doubt grew when you annealed it. I would first try to quench in oil, not water, to harden it. Since it's mystery steel nobody can say with certainty what temperature to use to temper it but I would try two cycles of 375 F for an hour each, water quench between each cycle, and check for brittleness. If it's too brittle at this point then I would try two one hour cycles at 400 F.

A lot of people frown at using mystery steel for knives, especially springs because of the possibility of stress fractures in the springs. That is something to keep in mind. I still think it's fun to repurpose steel but I haven't experienced spending a lot of time making a knife only to have it fail because it was mystery steel.
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Dustin Stephens
Anthony, I am not 100% sure what they came off of.  I got them from a buddy who has a junk yard and they were just lying on the ground, thats why i got them, ease of aquriement:>  He has alot of old chevy s-10s around so i assume maybe one of those??
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jmccustomknives
Most modern automotive/truck springs are usually some version of 5160.  I haven't found any yet that weren't.  If the springs aren't full of stress cracks they will be great to learn on.  Make a test blade, heat treat it then test it.  Usually that test will end in you breaking it (on purpose).

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Dustin Stephens
can you briefly describe that test for me?
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jmccustomknives
First, forge that blade out.  You'll have to do some forging at least to get it to stock removal.  Normalize then do your grinding.  You'll be looking for any cracks.  If you find cracks they were already there or you messed up on the forging process.  After grinding (I like to take it to 85-90%) heat treat the blade.  Quench in oil (canola should work well).  Once the blade is cool wipe clean and check with a file by trying to cut into the edge (no heavy pressure that can break the blade).  Temper at 400F then finish the grind.  When the edge is thinned out properly get a 1/4" brass rod and put it in a vice.  Press the edge at sharpening angle (up) and watch it close.  If it chips easily then temper again +25deg and repeat.  What you are looking for is that edge to deflect and return.  If it just bends then it's not hard enough.  If everything checks out you can then break it and read the grain.  Use a broke file to compare, you want the brake to look like the file (no visible grain structure).  You can avoid breaking the blade by forging out a 1" wide by 3/16" thick piece and doing the same heat treat and breaking it.

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Dustin Stephens
am i pressing on the blade edge with the brass rod?
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jmccustomknives
yes, that comes last.  Your just testing for the proper hardness.  It's also a good idea to do the test down the edge to make sure your heat treat covers the entire blade.  After this then you can do comparative testing by taking a good factory blade and doing some cutting.  I'll get a cutting board and some hemp rope for this test.  Sharpen to shaving then count how many cuts you get.  Do the test twice. 

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Dustin Stephens
ok, got it, ill let you know how it went when i get to forge again
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