rjs

Thanks Mikey, I pm'ed him with more or less the same comment. I was reluctant to say it in the forum since the heavy hitters were already taking their cuts. I hope he tries it and reports the results.

First of all best wishes concerning your daughter. Concerning your burner: There shouldn't be any flame at the rear of the burner. I suspect you have some propane leakage issues back there. And Frosty is gonna want to know some additional info on what you are using for a jet and what size it is? Also how are you adjusting/controlling your propane pressure and what do you have it set to? Regards, Bob

Yeah fire it up and play with the choke. You will find that there is no reason to completely choke the burner. The point of the choke is to be able to adjust the flame across the range of reducing to neutral to oxidizing at a variety of pressure settings. Oh yeah watch this video https://www.youtube.com/watch?v=VxzdqcPzXj8ob Bob

Agree on every point. This is essentially the same burner that dave hammer describes in his you tube video and the design seems to work well (at least for me.) Hose, regulator, and stainless steel construction all for under a hundred bucks seems like a great value. Bob

after a number of years without access to my oxyacetyline rig I have recently aquired another one so my interest in the propane/air rig was largely theoretical however the portability of thie unt still makes it interesting on some level. Interesting you should mention the twin carbon arc approch. those things seem to have faded into oblivion as the years have gone by. Back in the fifties (yeah i was around back then) there were ad's for them in all the how to magazines. I always suspected (i have never used one) it was because while they might work for some things they could not come close to the finess/control you can get with an oxyacetyline rig.

Hi Frosty, another reason those guys preheat their propane is that they take it out of the tank and up to the preheater as a liquid. If they tried doing it the way we do it they would quickly cool their fuel tanks to the 0 psi level. the one I was just reading about had two burners each rated at 15,000,000 btu's and no more fuel tank capicity than a lot of us have running our forges. "twin JetStream Series II burners, produce a heat output of 15,000,000 Btu's per burner or approximately 4,390 kW" and no I do not think I want one of those in my shop. Years ago one of those things landed in a field across from my place, they hit the burners a few times on the way down and it sounded kinda like a carrier was doing cat shots out on the sound. rjs

I hear that and I do not disagree. I took anofher look af the users manual and they do not rely on the hot air for ignition, instead they show some yoyo liighting it with a cigarette lighter. lol Certainly this is not a tool you could ever turn your back on and no one is suggesting using it as part of a forge. They do claim brazing heat with propane/air which I found interesting.

I think they are counting on it igniting the propane, the manual called for waiting for full electrical heat before turning on the propane.

Thanks Charlotte, I have looked at the sandia forge info and while impressive it all seemed a bit much. If horrible freight were selliing a chinese knockoff of these for a reasonable price I would just get one and to play with but they are not. Oh well. rjs

I came accross what appears to be a heat gun combined with a propane burner at this web site: http://www.onlygaz.com/pages/gas_torch.html Anyone know anything about these gizmo's? Articles posted on the site appear to be in french and all points of sale appear to be in France. They have an english users manual (pdf) it says that the unit preheats the air to 650 C and also preheats the propane some. The operating gas pressures are down around bbq levels ie very low. RJS

I am thinking that is a bit short for good mixing. How about some other opinions here?

how long is the 3/4 inch pipe? It looks a bit on the short side in your photos. Flame retention in the open air is a problem that goes away when the burner is in a hot forge.

have you tried one size larger? ( .035 if you are using mig tips)

jet size?

If that remark was intended for me, The hard bricks I was refering to came from a local tile shop. I am sure they were never intended for forge tempratures. I later found a local source for soft fire brick for a brick pile forge. after watching flux eat holes right through those I Moved on to a carved up five gallon propane tank with rock wool insulation and a floor of poured castolite 3000. bob

the ones I have melt after a while. I'm pretty sure they were intended for a fireplace floor.

He can have my old hard firebricks also (worthless for a forge.) Do all of us have a pile of those laying around dating back to when we were clueless? Bob

If you can replace the 120 tooth gear with a 127 tooth gear you can cut accurate metric threads. Regards,, Bob

with the propane turned off find out if your valve has a mehanical stop or if it falls out at full open. assuming it has a stop try your forge at the WFO setting. earlier frosty mentioned altitude, a good point. How high are you?

I looked at these forges at the diamondback web site and it appears the pressure guage is at the regulator and that there is also a control valve (needle/ball?) very near the burners true? Do you have this valve all of the way open? If not try that. As long as your guage pressure at the regulator output remains constant (where you want it to be) then tank freeze up is not the issue. I have seen crud clog up needle valves and jets requiring maintenance. Bob w bob

get a 0-50 psi pressure guage, stick it on the end of the manafold where you have a pipe cap now then report back with some numbers. oh yeah, and lose the attitude.

pressure is approx 4/10 of a psi from a bbq regulator, for a forge something on the order of 25 psi (adjustable) would be more in order. Then you will probably find that your jets are way to large. rule of thumb seems to be .023 mig tips for 1/2 inch tube, .030-.035 mig tip for 3/4 inch tube, .045 mig tip for 1 inch tube (inch measurements refer to nominal pipe sizes.) when things are working right these things are noisy. What you want is for it to run perhaps a bit lean when unchoked then choke it down to neutral to slightly reducing (rich) for work. Good insulation is important! once metal starts to glow it is radiating btu's at an incredible rate. iirc radiant emissions go up with the 4th power of the temperature (absolute.) much of this radiated energy can be returned to the work piece by surrounding it with good insulation which catches and re radiates the energy leaving the work. Velocity of the burning mixture is also important. hot gas loses heat in a hurry in contact with cold metal. it is important to have a good blast going to replace the cooled gas with more high temp gas. looking at your photos the flames appear very rich and way too low in velocity. use a smaller jet with more pressure to get more air in the mix and increase velocity. Have fun and be safe. Bob

1/8" pipe thread in the united states is 27 threads per inch. the taps come in tapered ( 1/8" NPT) which is what you need for 1/8" pipe fittings and streight (1/8" NPS) which are hard to find and only used for electric lamp fittings as far as I know. Also avliable are 1/8" NPTF fittings and taps (hard to find and more expensive than 1/8"NPT.) The threads on mig tips do not seem to be standardized so measure carefully and buy accordingly. ebay is you friend for odd size taps

next step, carefully take it apart and see what is inside.

I just noticed the bit about the door being open. sorry about that.