mikeb Posted May 10, 2009 Share Posted May 10, 2009 (edited) I have several old rasps I want to convert to knives, what is the best way to anneal , and then retemper them. I,m pretty new at this and just hope I,m asking the right questions. Edited May 10, 2009 by mikeb Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted May 10, 2009 Share Posted May 10, 2009 Search this site for annealing and heat treating There has a lot of information posted on here. Quote Link to comment Share on other sites More sharing options...
TechnicusJoe Posted May 10, 2009 Share Posted May 10, 2009 i thought the best way of annealing hardent metal is by making it about white/yellow and then letting it cool in the air, that's my way but i'm not sure if it is the best way Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 10, 2009 Share Posted May 10, 2009 Welcome aboard Mike, glad to have you. Do NOT heat the steel above non-magnetic during heat treatment. Orange or yellow is WAY too hot and will damage it. Gradually heat the piece and when it starts approaching bright red start testing with a magnet. Pull it from the fire and touch a magnet to it, if it sticks put it back in the fire, if it doesn't stick put it in a bucket of perlite and leave it till tomorrow. If it's real thin heat a larger piece of steel to near non-magnet to bury with it to slow cooling. If you click "User CP" at the top of the page and edit your profile to show your location it can make a big difference. IFI is represented by members from more than 50 countries and a lot of info is location specific. Also, if local folk know you're there they can invite you to get togethers, tip you to tool deals and offer hands on help. Frosty Quote Link to comment Share on other sites More sharing options...
Rob Browne Posted May 10, 2009 Share Posted May 10, 2009 Just a point about old rasps and files. After softening, get rid of the teeth by grinding or you risk cold shuts in your work. Quote Link to comment Share on other sites More sharing options...
Chris Waldon Posted May 10, 2009 Share Posted May 10, 2009 If, like me, you don't have a bucket of pearlite just standing by, I've heard that woodash works almost as well. my $0.02 Quote Link to comment Share on other sites More sharing options...
Finnr Posted May 11, 2009 Share Posted May 11, 2009 Get them red hot and tuck them in aq material that keeps air away. Pearlite, ashes and a host of other things will work. The main thing is a slow cool down. Finnr Quote Link to comment Share on other sites More sharing options...
kevin (the professor) Posted May 11, 2009 Share Posted May 11, 2009 (edited) If you have a well insulated forge,and you don't have pearlite or vermiculite, you can leave in the forge and just shut the thing off and block the openings with hot bricks when it is at or just below the correct temp. Adding a large mass of hot steel helps, too. I have a forge with firebrick floor and then "wool" under the brick and under the roof, with "wool" side insulation. It is venturi type. I put whole firebricks across openings, careful not to close too much and limit airflow. This helps with reducing hot spots and getting more even heating, too. I also place bricks just in front of opening to forge, so they get HOT. When time to anneal, I shut off forge with item inside. I then rapidly turn hot bricks so that they totally block the forge. If I had a kayowool blanket, I would put it over forge and bricks as last layer. In my forge, a knife sized cross sections cools to around 500F in about 4-5 hours. Not as good as vermiculite plus hot mass, but... This is a really simple trick, it works for 10xx and w1 or w2 and o1. It is not good enough for many other types of steel, where vermiculite with a hot brick or large piece of hot steel would work much better. It is just a way that works easily if all you have is your gas forge and fire bricks. You can get neat patterns on outside if you grind everything smooth but still leave the little "half moons" from the teeth. Looks like fish scale or feathers. This pattern happens if you forge to shape and then grind teeth off. If you ground teeth first, there would not be the little oxidized half moons at the base of each one. So, the surface of this knife is smooth as glass, but it has the "feather" look. If you leave the teeth during forging, don't forge the "middle" section too thin. The teeth will be nothing but a lot of cold shuts and weak spots after forging. You will need to have enough spine left between them, so that when they are 99.5% ground away the knife has sufficient stucture. OK, I went on a long time. Sorry. I have a lot of rasps. Kevin ps - this was the first knife I ever sold! Edited May 11, 2009 by kevin (the professor) Quote Link to comment Share on other sites More sharing options...
new guy Posted May 11, 2009 Share Posted May 11, 2009 that knife looks like a khukri to me. it is still very cool. i have found wood ash works well (along with everyone else on this thread). good luck Quote Link to comment Share on other sites More sharing options...
unkle spike Posted May 11, 2009 Share Posted May 11, 2009 Also standard Barn Lime will work....have used it myself. One tip I have though, don't put it in a plastic bucket, when a hot part tips over into the side, it will melt through the side of the bucket, and you will end up with lime all over the place. You shoud try to keep the part as close to the center of the bucket anyways. Quote Link to comment Share on other sites More sharing options...
Talon Tex Overland Posted May 18, 2009 Share Posted May 18, 2009 would wet sand work? Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted May 18, 2009 Share Posted May 18, 2009 NO it will not. In case you have not noticed, water is a good conductor of heat. To anneal you want to insulate the heat, to slow the cooling, NOT cool it fast. Quote Link to comment Share on other sites More sharing options...
Talon Tex Overland Posted May 18, 2009 Share Posted May 18, 2009 my bad... im still new to this. What about just plain old dry sand? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted May 18, 2009 Share Posted May 18, 2009 Not nearly as good as sifted wood ashes! (and if any was to melt to the steel a bigger pain to remove.) Quote Link to comment Share on other sites More sharing options...
Talon Tex Overland Posted May 18, 2009 Share Posted May 18, 2009 ok cool thanks...what do u mean by sifted? how do u sift ash? Quote Link to comment Share on other sites More sharing options...
Charlotte Posted May 18, 2009 Share Posted May 18, 2009 Window screen, hardware cloth , kitchen colandor... what evr. I like vermiculite my self but that is just me. Quote Link to comment Share on other sites More sharing options...
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