Can a manually-controlled salt pot be constructed for cheap?

cotdt

cotdt

Joined
Oct 2, 2006
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It would be nice to be able to heat treat any steel I want. How cheaply can a small salt pot be constructed for? I don't need the digital temperature control, I can adjust the temperature manually.
 
Patrickknives said:
Here is example of a propane salt pot, a digital controler does not cost much I am not sure what a low pressure propane valve would cost. I guess you can set up manual and then switch,

http://www.bladeforums.com/forums/showthread.php?t=647313
Click to expand...

Thanks for the link, I missed that one in my research. It LOOKS like I can construct a salt pot for under $100 if I use some scrap parts, but commercial units sell for $2000 so I must be missing something? If I want to heat treat in the range 1500-2200 F, what salt should I use?
 
You are missing the fact that a salt pot is extremely dangerous if not made right.

Yes, you could do it with scrap parts for $100, but any failure could be catastrophic.
At a minimum, you need a heavy walled stainless steel tube with the bottom plate properly welded on. Darren Ellis carries these fairly inexpensively. The forge that will heat it is very basic, and can be build from any scrap, like and old hot water tank. The controller should be controlled, and preferably programmable, to allow for smooth and even heat up. You don't want a volcano going off in the smithy.
A salt pot can probably be built for $500-$700 depending on what you already have. This is one of those places where you have to do it right.On the tube - If you aren't a good welder who knows stainless welds....get it done professionally, or buy it from Darren.
Stacy
 
bladsmth said:
You are missing the fact that a salt pot is extremely dangerous if not made right.

Yes, you could do it with scrap parts for $100, but any failure could be catastrophic.
At a minimum, you need a heavy walled stainless steel tube with the bottom plate properly welded on. Darren Ellis carries these fairly inexpensively. The forge that will heat it is very basic, and can be build from any scrap, like and old hot water tank. The controller should be controlled, and preferably programmable, to allow for smooth and even heat up. You don't want a volcano going off in the smithy.
A salt pot can probably be built for $500-$700 depending on what you already have. This is one of those places where you have to do it right.On the tube - If you aren't a good welder who knows stainless welds....get it done professionally, or buy it from Darren.
Stacy
Click to expand...

Thanks for the response. How much would it cost for the salt? How much for the digital controller?

I have a 304 stainless steel tube with 3.5" diameter and 1/4" inch wall thickness. Would this work? I can ask a friend to weld it for me.
 
I had a manually controlled pot before PID controllers came out....note I said HAD. I was using a mild steel tank, and doing everything on the cheap...mainly because I didn't know any better at the time. It nearly cost me my shop! The salt tank gave out, and thank God at that time I was working in a dirt floor smithy shop! 1500F+ molten salt went running everywhere, caught one wall of the shop on fire, and after several minutes of frantic dirt throwing, and some big burns on my hands/arms, I got it contained, and only had to replace one wall of the shop. Once that pot cooled down, I tore it apart, scrapped the pieces, and never even considered another salt pot until I discovered PID controllers.

Listen to what Stacy wrote! "Cheap" IS NOT A PHRASE TO ASSOCIATE WITH A SALT POT! Suck it up and do it right, or don't do it at all!!

The PID controllers can be had off Ebay for $40 or less, a good thermocouple is $20, the "forge" part can be made out of scrap for near nothing if you own a welder. The tank is the heart, so cost isn't an issue...spend what you need to to contain the molten salts. The gas valve is around $60, and the hoses/fillings another $30 or so. Here's a link to the one that currently resides in my shop:
http://www.caffreyknives.net/bsteel.htm
since those pics I have upgraded the PID to an F model (all they had at that time was C readouts), but otherwise its the same.
 
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A caution about using electric salt pots. The salts and their gasses are conductive. The coils have a way of touching the tube,too. When you put in or take out the sword/knife, a severe shock is very likely. Ask Kevin about why people switch to gas salt pots.
Stacy
 
You guys crack me up, is there anything that has not been done on this forum. I am always amazed at the work everyone has done in this craft.

Back to the orginal statement 'It would be nice to be able to heat treat any steel I want'

most have found a forge or kiln to meet this need unless you are doing something different like a sword. Is there something specific you need to do that may need a salt pot.
 
Salt pots are suburb at austenitizing steels in the 1500-1600F range. There is no de-carb or scale. They are also superb for marquenching the steel in 400F molten salt. The next thing they are superb at is tempering. The advantage is largely due to the greatly higher rate of thermal transfer in a liquid than in a gas. The PID control will allow you to dial in any temp and hold the steel for any soak with ease.When everything is ready, pull the blade and quench. The salts are readily available from Darren Ellis and many HT suppliers. With care to keep them un-contaminated, and occasional restoration to good condition, they will last a long time. Trying to use home brew salts is like trying to use a scrap yard salt pot....fraught with problems. Like the tube, get the real thing in salts. BTW, HT and LT salts are not the same.
Stacy
 
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