tempering old blades

M

miarrow

Joined
Apr 4, 1999
Messages
65
as a rookie i thought i could try grinding some old kitchen knives that appear to be made of a soft hi-carbon steel, once i have them gound down to a smaller size will i have to have them retempered.
 
No. Not as long as you keep them cool when grinding. Grind,dip-grind,dip...Dont let the steel get so hot to the point that it starts to change color...Good luck.
 
If they are both high carbon and soft, wouldn't you want to improve them by hardening them through heat treating? I assume you are replacing the handles. Just bring them up to non magnetic with a torch and leave them over night in a pail of vermiculite. This will anneal them. Grind the soft steel to the shape and finish you want and then reheat to non-magnetic and quench them in an oil such as ATF. Temper in a 375F oven for 1 hour. finish and put on new handles. That should do it!

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Ron Ruppé
www.ruppe.com/Knives/index.htm
 
hey, ruppe that just what i would like to do but "non magnetic"?

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never seen a knive i didn't like
 
One way is to judge the temperature by the color the steel glows, but differences in ambient light can throw you off. A less subjective way is to touch a magnet to it. When the magnet doesn't stick it's hot enough.

-Cougar Allen :{)
 
First let me say, there are others who certainly know more about the following than myself. That said, I do make knives and heat treat them myself. Here goes. Taking carbon steels up to the Austinetic (non-magnetic) state allows you to harden them if you cool them rapidly (quenching). If you, on the other hand, have a carbon steel that is already hardened, you, instead of quenching them, allow them to cool very slowly, you soften them, ie remove the effect of any previous heat treat. The vermiculite (sp) is available from any garden store. It is a very good insulator. The process of putting the heated blade in the vermiculite allows the blade to cool very slowly. I have achieve the same annealing by leaving heat treated steel in my heat treat furnace for slow cooling and in the coals of a very hot bon fire until cool.

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Ron Ruppé
www.ruppe.com/Knives/index.htm
 
i was wondering about the vermicult my self, but i just rode out to frank's nursery a bought the last bag. i'am going out right now and give it a shot.
 
I might add that to reach Austinetic state, you will need a very good source of high heat. I've done it in a heat treat oven, a forge, with oxy-acet. welding torch, a huge all night desert bon fire on a very windy night, and once in my barbeque with charcoal and an electric hair dryer. I believe with 5160 steel, your talking about 1650F

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Ron Ruppé
www.ruppe.com/Knives/index.htm
 
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