Jason,

Since Dee is an ABS JS here's a link to a WIP on a sword tempering furnace she built and posted elsewhere. I don't know if she has ever tried to use it for full heat treating so you might pm her to find out.

Good Luck and be safe,

Mike

On Don Fogg's site he shows a heat treat forge made out of a 55gal drum, lined with kao-wool and fired with a single burner controlled with a PID and solenoid. Jesus Hernandez uses the same type and speaks very highly of it. It seems like it would give a lot of the control of a salt bath without the cost and danger. Oh, and then there are salt baths which would be best but are fairly expensive to set up and quite dangerous if you are not very careful. -Justin

Thanks Mike! <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' /> I had a show last night so I didn't get a chance to write her but I will be sure to tomorrow. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' /> And Thanks to you too Justin. I'll have to check that out as well. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

I have two electric salt tanks, one I built and one that was commercially built for me. Both will heat treat swords. My third tank has low temp salts and it is horozontal rather than vertical like the two high temp tanks. L&L kilns built my largest of the two high temp tanks and they built it for the purpose of high temp salt tank. It will take a sword of 37 inches in blade length. The nice thing is that I have preset programs computerized for my use (I had to program these into the computer that controls the heat). If I am doing a subcritical anneal it is program 1. If I am heat treating 5160 it is program 2, 52100 program 3, W2 program 4, etc. I use a probe in the salt solutions to check for temperature of the salt and not the surrounding atmosphere. The digital reading on my high temp is about 12 degrees cooler than the salts and this corresponds to the data given me by L&L when they made the oven/kiln. My probe is calibrated about every time I use it to a standard. If one of them is off I recalibrate using a third source to match with one of the two other temperature readings. I like precision and while that is not a perfect situation, it is pretty good.

So the bigger the gas fired forge the more variation in temperature both within and across time as the thermocouple regulates firing of the propane. I like the salt better since it is relatively a large mass providing heat by conduction rather than convection. Knives heat faster in salt than they do in a gas atmosphere. Oxidation is kept to a minimum.

A heat treating oven that approximates the size of a 50 gallon barrell would likely mean that it is hotter in some places than others (center of chamber, sides, side opposite burners, etc.). If you make the circumference smaller (10 inch inside diameter over the 18 or 20 inches approximate diameter of a 50 gallon drum) you have to be concerned with the location of the burners and how many burners along the length of say 36 inches for a sword. Insulation becomes critical to reduce cold spots. Smaller heat treat forges have fewer problems with temperature variation but they are never as precise as the salt. If you want precision, go salt.

Dan Petersen

Actually Dan I would like to go with the salt baths, I just don't know allot about them. The theory of an even heat is appealing. I want to be able to do several blades at once. Can you normalize, anneal, and temper with the salts? Are they the same salts you would use to blue a blade? If you have any good info about setting up my own I would appreciate it. Even if it's just links to tutorials. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />