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first propane forge


Old South Creations

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I finished my first propane forge today. I used Frosty's design for the burner. It heated a piece of 1/4" x 1/2" flat bar to orange in just a few minutes but wouldn't get any hotter. I think I need to fine tune the burner a bit. I'm only going to use it for small items...hooks, nails, leaves, etc...I'm planning on using my coal forge as my primary forge.

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A pic will really help but describing the burn might do. What's it sound like? What does the primary flame look like? Is there dragon's breath? What color is it? What dia. is the burner tube? What volume is the forge chamber?

Frosty The Lucky.

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A pic will really help but describing the burn might do. What's it sound like? What does the primary flame look like? Is there dragon's breath? What color is it? What dia. is the burner tube? What volume is the forge chamber? Frosty The Lucky.
I've never really been around a gas forge before so I'm not real sure what to expect. When I first light it there is a lot of orange flame and the sound is broken...like a put-put-put. It settles down pretty quick and there is a nice bluish/greenish flame and the sound is more of a steady low roar. There seems to be a lot of Dragon's breath...more than I expected. The burner tube is 3/4" and the tee is 1" x 1" x 3/4" and I'm using a .035" contact tip. The forge is constructed of fire brick and the inside dimensions are 7 1/2" x 3 1/4" x 4 1/4". When I lit the burner outside of the forge it sounds like a jet engine and the flame is what I would describe as very unorganized. A much bigger/wider/longer flame than I expected. I won't have any time the next couple of days to play with it. The first thing I was going to do was cut down the contact tip by an 1/8th inch and try it again. I know that the design is a very sound one and a lot of people are using them. I used Phil Krankowski's tutoral to build it http://www.iforgeiro...-and-made-this/ I have no doubt that it will work just fine, I just need to some time to "play" with it a little bit. I know it's hard to imagine what it's doing by my description...I will try again tommorrow to post a couple of pictures.
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I cut the contact tip down by 1/8". What a difference an 1/8th makes. Got a 1/8" rod to forging heat in about 2 minutes or less and a 1/4" x 1/2" flat bar to forging heat in about 5 minutes. Flame seems much more stable and uniform and the sound is very smooth and uniform. I still can't seem to heat past a orange to yellow/orange though.

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Old South, if you're having trouble uploading or posting the pic here, try uploading it into a free photobucket account and then copy and paste the IMG code into the forum, it will look like code on your screen, but once its previewed/posted the image will show up.

Blake

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Thanks...here is a picture of my forge. I'll try to post a couple of pictures of the burner working in the next couple of days. I used it for the first time today. I fired it up for a little over an hour and made a couple of "s" hooks out of 1/4" round and a RR spike tomahawk (still need to finish the hole for the handle). It gets a RR spike to a yellow/orange in just a few minutes. Producing a lot of scale right now. I'll adjust it a little and try again.

002.jpg

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Thanks...here is a picture of my forge. I'll try to post a couple of pictures of the burner working in the next couple of days. I used it for the first time today. I fired it up for a little over an hour and made a couple of "s" hooks out of 1/4" round and a RR spike tomahawk (still need to finish the hole for the handle). It gets a RR spike to a yellow/orange in just a few minutes. Producing a lot of scale right now. I'll adjust it a little and try again.

002.jpg

It looks like this is soft firebrick - am I right?

If so, then you probably need to coat the inside with ITC100 or PLISTIX, which will make the brick reflect a lot more heat, which increases the efficiency of the forge by a lot. Your forge is very similar to mine.
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John: By your description it was burning rich and shortening the jet is the easiest way to induce more air. Until you have a good handle on how long they need to be don't make adjustments so large, 1/8" is a really big adjustment, I do the fine tuning in 1/64" increments.

How long is the burner tube? If it's too short the fuel and air won't mix well enough so you can actually end up with a seriously oxidizing fire in the chamber and still have excessive unburnt fuel escaping the doors. (dragon's breath)

Stuttering is a sign the flame was well out of adjustment as was a soft or feathery flame. When properly adjusted these things are really loud, like a small jet engine in the shop, it's hard to talk near them without shouting.

Coating the refractory liner is a really good idea, fire brick is mostly silica and so really susceptible to caustics like hot flux. ITC-100 is my pick, it's zirconium oxide flour and kaolin clay making it really resistant to fluxes. It's also a darned efficient IR reflector so you get to keep more of your heat where you want it.

Pics will help a lot. The one of your forge makes me think part of the scaling is caused by room air being drawn in (induced) into the forge by the flame. My forge will scale a little if I have it wide open but closing the doors a little cures that just fine. That's just speculation though, your mileage will probably vary.

Frosty The Lucky.

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Thank you JCornell & Frosty. I had cut the tip down by 1/8" because that's what I read to do. I have plenty more tips to experiment with...I'll go with 1/64" at a time like you suggested. Thediameter of the burner tube is 3/4" and it is 6" long...is that long enough? I'll coat the inside of the bricks as well...I have Plistix already, will that be good enough or should I order some ITC-100?

Thanks for all of your help. This is a lot more complicated than coal! :)

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I experimented with size of the contact tip and I think the burner is running much better...heats quickly with very little scale. My only complaint would the amount of dragons breath. The flame extends approx 10-12"...before it was more like 16". Is it possible that my forge is just too small for the burner? It's hard to capture the dragons breath but this shows it a little (sorry the pics are so big...it's the only way I've been able to get them to post)
005.jpg008.jpg

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The ratio for tube length is 8x the dia. so 6" is just right for a 3/4" throat but it isn't a set in stone ratio but a little longer is better than shorter. Your's is just right so don't worry about it.

Doing a little math says your forge volume is around 100 cu/in and one of these burners will easily bring 300-350 cu/in to welding heat at a modest prop PSI. So, make your forge about 2-3x as large, the dragon's breath will be much closer and you'll start to grow hair on your hand and arm again. One 1/2" burner would be close to just right for what you have being about right for 150 cu/in.

Personally I find it easier to fit brick than build and tune burners and when my lathe is set up it takes me about 15 mins +/- to build and tune a burner. Just takes practice.

Frosty The Lucky.

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