[Jon Koppel]

Hey all, this is my first post and I’d like to ask for advice in building a burner for my first gas forge. I’ve already fabricated the body based on the design of the forge that I learned on. It is 20 inches long and 12 inches in diameter. After I’ve added the 3 inch refractory lining the internal diameter will be 6”.

I don’t know how finicky all the specifics of the burner construction are, so I’ve decided to err on the side of caution and ask for advice from an experienced community. Now that I’ve gotten to the point of building the burner I have a bunch of questions. I’ve attached a photo of the body of my forge so far, a photo of the forge that I’m basing my design off, and the label on the blower of said forge.

What should the internal diameters of all the pipes be? Of the mixing chamber? How much does it matter?

Are the 90 degree bends in the gas pipes and the pipes from the blower (see the photo of the MassArt forge) important?

The burner on the MassArt forge goes straight down at a tangent to the inside curve of the forge, but I’ve heard that having it go in horizontally at a tangent to the inside curve might be better. Thoughts?

I’m content to fabricate the system out of pipe and fittings when I can, but what actual hardware do I need? I noticed what looked like venturi holes on the pipes leading from the gas to the mixing chamber.

What are the specifications of an appropriate blower? And where can I get said blower? I’ve looked at MSC and Grainger and couldn’t find anything that looked appropriate.

I know that the pipes that convey the gas into the mixing chamber penetrate a few inches into the mixing chamber. Is the exact distance they penetrate important? Is the aperture size important?

Is the fact that the burner enters the forge at 3 ports important? Helpful? Unnecessary? Would one entry point be better? worse? doesn't matter?

Is there anything I’m forgetting?

Thanks a lot in advance.

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[Jeremy Lindley]

Hi, Jon-

That forge looks like a beast . Let me preface my comments with the fact that I built a 2 burner venturi forge, not a blown one. That being said, I nearly built a vertical blown forge and asked quite a few questions about it. The best part is, there are a bunch of guys on here with a TON of good info on building good forges and will likely come give you a hand soon.

One of the reasons I didn't end up going with a blown forge was I couldn't find a blower that wasn't pretty expensive (a ways over $100.00). And from what I remember, I was told I would want one in the 130ish cfm range. As for 90 degree angles and such, I suppose if you had a way of making it a more gradual angle, that might be better, but I don't imagine necessary. I've seen plenty of forges that reach forge welding temps and the gas and/or air has to turn at least one 90 degree corner. If you don't mind my asking, what are you planning to use for the lining of your forge? You mentioned it'll be 3" in thickness-is it going to be kaowool or castable? I used kaowool and put some kiln cement refractory over it, then after I saved a few pennies, lined over that with ITC 100. I can say from personal experience, the ITC was well worth the money and has made a noticeable difference, both in how quickly it heats up the interior and how much faster my material gets heated. Although, with 3 burners and a blower, I imagine whatever you use will get piping hot in no time.

I'm sure the more experienced guys on here will be able to help you out with the mixing chamber and how many burner ports, etc. Good luck and I look forward to hearing how it all turns out.


Jeremy

[Jon Koppel]

Hi Jeremy, thanks for the response. I don't mind spending a little money on a decent blower, I'm likely to get a $500 grant for an arts festival to do a demo this year. It's a yearly thing and I got it last year to build a bronze furnace that worked out quite nicely. I'm actually using some refractory left over from that project. It's a plastic refractory that is rated for 3000 degrees. In the future I would probably go for castable over the rammable, if only for easy of installation. The result is the same. I've used castable in the past.

[Dale Huckabee]

Hi Jon,

Check out this site www.dfoggknives.com/forge.htm. I've built several forges and burners using this design. All have reached welding temperature and I'm still using the first one I built. I did add a gate valve ahead of the blower to control air flow and I put a needle valve in the gas line to give better control of the gas. Hope this helps.

Dale

[Brian Thie]

Hi Jon

I have forge similar to what you are building. I did mine with castable refractory and used a 6" piece of stove pipe for the internal form. I just have 1 burner with a blower of around 100 cfm if I remember right. The burner is horozontal coming into the forge body at a tangent to the top. The interior is 12" long and reaches welding heat with no problem.

As far as blowers, try www.surpluscenter.com - this is where I got mine.

Brian

[Jon Koppel]

Thanks for all the responses.

I guess at this point I have two concerns that I'd like to lay to rest before I proceed.

1) Is a single burner enough? The one I'm used to has 3, but it's been pointed out that they point downwards and heat the metal directly making having multiple burners more necessary. With the burner pointing to the side the heat is indirect, heats the whole forge, and therefor one is sufficient. Is this true?

2) Is a 60 cfm blower strong enough. I've heard 130, I've heard 50 or less, I've heard 40-100, I'm just not sure which is true. But I found this blower http://www.surplusce...atname=electric and it seems to be what I'm looking for, if 60 cfm is strong enough.

[Dale Huckabee]

I'm using an 80 cu. ft. blower that I got from Surplur Center which is more than enough. I use a gate valve to control the amount of air going to the forge. I see no reason why a 60 cu. ft. blower wouldn't work.

Dale