Gas forge Vs. Coal forge for HT

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danool13

Joined
Jun 12, 2013
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once again i seek the guidance and wisdom of you all here on bladeforums.i am buying/building more equipment and am ready to build a forge. as said would a blown horizontal propane forge or a tim lively style coal forge be better for heat treating blades? most blades that i make are 6" - 9" but i am wanting to build a 13" chopper so need something to handle both. with both of them is it necessary to put the blade in a pipe in the forge in order to balance the temperature for heat treating? also what is the ideal amount of air (CFM) for both forges? thank you for your help on this topic. and if there is something better as well please tell me, short of an oven not ready for that yet.
 
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I do all my HT in my horizontal propane forge. It is 18" long and I can effectively HT a 16" blade easily. Longer if i make some temp mods. I can control the heat in the HT ranges for carbon steel. It provides a nice even heat so the pipe is not required. It would be a little harder to do this in a vert forge. The thing I really like about the propane is it is much easier to use a thermocouple and controller.

You can do a coal forge and create a trough. But it is much harder to get the temps right and difficult to do a good long soak.

The blower I have I got out of an old RR signal box. I think it runs about 65cfm. They sell a 110cfm with good pressure at high temp tools.
 
thanks chuck for your help, i apologize i meant a horizontal not vertical, i may end up doing a vertical later for damasus. i have looked at high temp tools site and cant seem to find the blower-- i was planning on contacting mr ellis when i made a decision on the forge and possibly driving down to him to get supplies as im only an hour and a half away
 
Well guess its been a while since I looked. They used to. Might want to drop them a line and ask if they can get one or where they would recommend..

I do my Damascus in my horizontal forge too. I do most of my welding dry so I don't need to rebuild that often.
 
I have a propane heated forge specifically for HT. The internal working dimension with the insulation and refractory coating is 5x5x15. Because of the relatively small volume I can keep the temps pretty close to dead on, very efficiently an evenly to say about +/-3 degrees. Using a JF#1 burner.
 
karburized i looked at the jf#1 burner, that thing looks wicked. would you say it would be as good as a blown setup though? if so i may go that route.
 
danool13 said:
karburized i looked at the jf#1 burner, that thing looks wicked. would you say it would be as good as a blown setup though? if so i may go that route.
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Honestly, I don't know. I can't imagine not, if you were to use the actual forge chamber as the intermix-chamber. Suffice to say my forge is capable of reaching and maintaining 1900F with little difficulty and still have plenty of room for adjustment using only the venturi effect inherent with the burner.
 
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You will get all kinds of conflicting info on LP vs. Coal and Blown vs. Venturi.

An advantage of a coal forge is atmosphere control. You don't get that with your typical gas forge. Another is heat concentration and control. Some find coal easier to control, while others figure out ways to regulate heat using propane(muffle pipes, PIDs, etc...). Some also claim a blown forge uses less fuel than a venturi... but I have yet to see any real testing to provide evidence. I like my venturi LP forge but have plans to make a blown vertical unit for pattern welding.
 
A solid fuel forge is easier to get hotter, but that's not necessarily what you're wanting for heat treatment. It's a lot easier to burn up your steel in a solid fuel forge because of that and because of the fuel hiding the blade from view. But, a solid fuel forge is simpler to build.

In either case, using the heat muffle (pipe) method is a good idea for evening out the temperature and keeping from getting too hot. You can also put wood slivers or such into it to consume the oxygen and reduce the amount of scale.
 
ok so i decided to go with a propane forge for now, i will probably build a lively style one later to teach my boy scouts. i am having the hardest time deciding between a nice venturi like the jf#1 or a blown setup from high temp tools. also does anyone know were i can find or have a link to the plans for a variable blown burner, i saw stacy posted one a while back but cant find it. i am going to make the forge body out of an old 5 gallon air tank, will that be good enough or should i try to get a hold of some 8"or 12" pipe.
 
storm crow thanks for the tip with the wood chips in the muffle, it makes perfect sense when you think about it
 
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