Nicholas

Go to the Apprentice Corner Forum, second page. Click on Where to buy forge burners. There you will see a picture of Karl Anderson's forge and blown burner.

He uses a blower, but you could convert it to compressed air I would think but I do not know why the blower is so easy.

A blown burner is so simple.

All so go to the Tools, Equipment and jigs forum, for an excellent, Building a Vertical Forge tutorial by Master Smith Ed Caffrey.

Hope this helps some.

Anthony

Yes, a blown burner is the way to go whether you are building a vertical or horizontal forge. They are simple!

Bob

lined with 2-3 inches of ceramic wool

Just some insight on that part of your post.... while the common thinking is that with ceramic wool "more is better", it's not. I've tested 1" and 2" of ceramic wool in the same shell, and found that 1" takes less time to reach heat, and less fuel to maintain the temp. Most folks don't understand how ceramic wool is engineered..... to absorb a specific amount of heat, then start reflecting a percentage of that heat. 1" is designed to absorb the least amount of heat before it starts reflecting, and reflects a higher percentage of the heat then 2" (that includes "stacking" 1" material to equal 2 or 3") The end result is that you will use more fuel, at a higher PSI to achieve/maintain heat is 2 or 3" ceramic wool, then you will with a single layer of 1".

I plan on piping in compressed air controlled by a needle valve

Personally I would think that using compressed air (I'm assuming you mean an air compressor with the "hose" being fitted to the burner assembly) would be far more complicated then a simple forge blower. I can't be sure, but I suspect using a compressor might create volume issues, as in not enough air volume, at least in the context of using a needle valve....it's not going to give the air volume you need. You have to remember/realize that there's a huge difference between PSI and Volume when it comes to air and a forge. It's like water through a pipe...... a much greater VOLUME of water can flow through a 2" pipe, whereas much less volume can make it through a 1/4" pipe in the same amount of time, unless it's under excessive pressure....which is something you DO NOT want in a forge application (excessive air pressure).

just to chime in, the simplest of all setups is the venturri burner. You can look at the designs by Chile Forge from Texas and see them, or search T-Rex burners. Both of those models work great, and you don't need anything but a propane bottle. Weld easily and well, tune the forge atmosphere, and no electricity needed.

Blown burners are dead simple, though. Just a pipe with a barbed propane fitting put into a hole that you drill and tap. Have the air going through the pipe, and inject propane from the side, about 6 or 8" away from the place where the pipe reaches the forge. Maybe even farther, by a tad, to keep your propane line away from the heat of the forge.

You can get great results with either model, and don't need to worry about a compressor. A blower doesn't cost much.

Also, as Ed alluded, you would have to find a way to get your compressed air to be lower pressure and high volume, which will require some additional piping/plumbing.

Just my own opinions, but it works for me. I have a 2 burner Chile forge, and I am building austenizing and tempering furnaces out of 55 gallon drums using a 3/4" T-Rex and a, "shorty," burner. The Shorty is their small version, that can run at low temp, and also be used as a hand torch for soldering and brazing. I have been relying on maap gas bottles, and I don't like them. For a long time, there was a safety risk associated with them, and I want to get away from them.

Awesome. Thank you for the replies. I tinkered a bit before reading these.

I was able to get the needle valve working fine. I just don't like the noise from the compressor. It's obnoxious. The needle valve only needs to be turned less than a quarter turn to pump enough air into it to get the burner optimal, but I can't stand the noise, and it runs a lot (I only have a 20 gallon, 6 cfm compressor).

I modified my forge and burner to try to take in a miniature shop vac, which I slowed down with a variable speed dial but it's way too powerful, and still too noisy. So I scrapped that and just ran it as a venturi. I melted my nozzle after about a half hour of trying it out, so that's one of the coolest "whoops!" I've ever had haha. There's about a quarter cup puddle of steel cooling in the forge now.

I assume forced air runs quite a bit more efficiently. That's really why I want to get this going. I'm now pretty happy with the swirl I have going in the forge, but I have to run the PSI on the high side to get to welding temperature. I'm using a .025 mig tip as my nozzle, so I know PSI at that point in the chain is subjective. But I think when I had the needle valve/compressor setup dialed in, I was running less than half the propane for the same heat.

Thanks for the advice on the ceramic wool. When I crack it open tomorrow, I'll reduce the wool. I have 3 1 inch layers right now. But that was less to hold the heat in and more to optimize the size of the inside of the forge. 1 inch gives too much space in a 20lb propane tank, or my opening is just to big (probably about a 4 inch diamemter)

Maybe I can try 1 inch in it and just fit a sliding door on the front so it keeps the heat in better?

How many hours do you expect to get out of 15lb of propane from your experience? Any idea where I can find a blower for a reasonable price? I was thinking a 4 inch exhaust duct blower with variable speed, but even those are in the $70-80 range. I was even thinking of a blow up mattress blower, but they're loud too. Old 10-12 inch forge blowers are quiet, but people want like $150-300 for them. I've seen similar 8 inch blowers on electrical equipment kicking around our lab (I'm an engineer), so I assume they still make these commercially somewhere.

Thanks for the suggestions. I'll tinker a bit.

-Nick

Nicholas,

At the bottom of my Jigs & Fixtures page, is information on how I build my propane forges. My burner assembly is at the very bottom of the page. I provide the model number of the blower that I use on my burner assemblies. It is a 146 cfm unit, bought from Grainger Industrial Supply.

Culver Jigs & Fixtures

Awesome info in there Steve. Thanks!

I'm trying to think of things I can cannibalize for next to free to put this together. It looks like dryer machines have a decent blower in them. I'm gonna see if I can tear one apart and use that.

I really like your torch build. Very simple. How much propane do you use with that thing?

It's difficult to say how much propane any given forge will use. Propane use is as much related to the efficiency of the forge than it is to burner design. In my shop, I run my forges off my 500 gallon tank, which also supplies our house and my shop. I used to bring my forges to the Heartland Symposium, for use in all of the forging demos. When there, I ran them off a 100lb tank. I set the regulator to 5lbs. While the forge was running, the gauge would read about 2lbs.

I would caution you on the size of the propane tank that you use for running your forge. Smaller tanks do not work well. Evaporation of the liquid propane into gas requires heat. As your forge is running, the evaporation of propane in the tank continually cools the liquid propane. In a small tank, the liquid propane will eventually get so cold that it does not evaporate quickly enough to keep up with supplying the forge. You really need at least a 100lb tank to supply a propane forge.

Just to piggyback on what Steve said.....go with at least 100lb bottles. Most folks who try to use the 20lb bottles usually freeze up the tank by the time they've used 1/2-3/4 of the capacity. (for the exact reason Steve spoke of).

|quoted:

Just some insight on that part of your post.... while the common thinking is that with ceramic wool "more is better", it's not. I've tested 1" and 2" of ceramic wool in the same shell, and found that 1" takes less time to reach heat, and less fuel to maintain the temp. Most folks don't understand how ceramic wool is engineered..... to absorb a specific amount of heat, then start reflecting a percentage of that heat. 1" is designed to absorb the least amount of heat before it starts reflecting, and reflects a higher percentage of the heat then 2" (that includes "stacking" 1" material to equal 2 or 3") The end result is that you will use more fuel, at a higher PSI to achieve/maintain heat is 2 or 3" ceramic wool, then you will with a single layer of 1".

So how does this work/relate to combining wool with castable refractory? I was looking to do an outer wool lining with a thicker castable refractory lining inside that. My build is with an old bbq propane bottle. I have Kast-O-Lite 30 for the refractory.

If I understand correctly, you're talking about placing the castable next to the forge body, then lining the inside of that (the forge interior) with kawool? If so, I would encourage doing just the opposite.....place the kawool next to the forge body, then "pour" castable as the interior of the forge. Far more durable.

Keep in mind that whichever you do, make the castable at least 3" thick....otherwise you'll loose more heat then you gain, and in less then 3" thickness, the castable will crack and crumble in a fairly short time....depending on how many heat/cool cycles it goes through.

Probably the biggest drawback to having castable as the interior of a forge is the longer heat up time, but in my opinion the longetivy/durability more then makes up for that.

I was talking about castable over wool. The castable would end up about 3-4" with what I had in mind. Sounds like I was on the right track with it. Thank you!

Just to follow up, I gave up on the forced air for now and just tinkered with the venturi setup. I repositioned the kaowool so the internal shape is more spherical.

Before I had the pipe about 30 degrees off center. It's not enough. Now it's almost 90, but it's offset so it gets a great swirl.

It's burning much hotter than before at the same PSIs I was using.

Good! Glad you got things "better" without having to build/rebuild. I think your post should be a learning lesson to many.....just goes to show that when it comes to a propane forge, a little thought and tweaking can go a long way!