You've been read'n my mail Jason. I've spent a good bit on all the parts to do this naturally aspirated burner as described in this tutorial by Nathan Creel yet and having the same issue with my setup however I've yet to install my new stainless flares I just finished.
http://www.arscives.com/bladesign/forge.tutorial.htm
I finally found the Ward brand reducing tees here in Houston and bought a 1/4 in. NPT treading die; I had all the rest of the taps and dies. Anyway, it IS hot! as you say. I'm doing a three burner model. I'll post some pix if you like.
That tutorial: ( did you use/see this one??)
http://www.arscives.com/bladesign/forge.tutorial.htm
As to your questions, for myself, I think I'm going to grind out the threads there at the choke plate's 1.25 inlet as this can only give you more air flow for the burner and, of course, you have a choke plate with which to shut off all or part of that maximum flow rate so the size of that opening really doesn't matter much
UNLESS you need more air!.
As to the flare getting hotter with less preasure, thats because the flame ignition point is closer to the flare the less pressure you use. I've encountered this problem on two other burners I made of this type and I think its because there isn't enough air in the propane mix when it exits the burner tube. As stated in Creel's tutorial:
"Nozzles can be made, but getting the flare just right is difficult. See Mr. Reil’s sight for the correct flare dimensions."
Amen. I'm grinding my own and doing it slowly with a "tryout before proceeding" plan in place.
Here's Reil's take on it:
" One of the most common complaints I receive concerns not being able to achieve welding heat. The naturally aspirated burner is easily capable of reaching welding heat, and above, but it is easy to "defeat" your burners if you create any "back-pressure" in your forge chamber. The burner operates by creating a low pressure in the throat of the burner bell when the high velocity gas stream injects down the throat of the burner. The low pressure sucks in air to mix with the gas stream creating a "balanced" mixture for burning in the nozzle and forge chamber. The low pressure is a very weak one, and if you bottle up the gasses in the chamber by restricting the exhaust opening area in your forge chamber, you will reduce the amount of air being sucked in, but not the amount of gas being injected. You will then see a lot of blue flame emitted from the front and rear, if you have a rear opening in the forge, which you should. The chamber will be running cool, and very fuel rich. The gasses will seek the oxygen outside the forge and you will see a secondary burn at the opening to the forge, especially in dim light. There will normally be some light yellow flames, but there should not be any blue flames emitted from the forge. The blue flames should not reach any further from the burner than the floor of the forge at maximum, normally less. "
And on flares, Ron writes:
"If you would like to buy premade burner flares that have a perfect 1:12 taper, and made of stainless steel no less, there is now a source. Most of the problems that I deal with when helping guys with burner problems relate to the rate of flare of the burner flares that they put on their burners. If the flare is not made correctly the burner will not function correctly. I was astounded when Larry Zoeller sent me one of his "press formed" stainless steel flares to try. I removed one of the old forged flares from the number one burner on my four burner forge and installed Larry's stainless flare. My old mild steel flare came off in fragments, as it had totally corroded through in only two years of use. The best I had been able to do for "idle" pressure with my old forged flare was 2 psi. Below that the flame would start to pulsate or huff. When I put Larry's flare on the burner it easily held the flame steady all the way down to a little below 1 psi! His flare just doubled the "idle" economy of my forge! I have ordered 7 more from Larry, they are that good. I can certainly make my own flares, but to obtain the precision that Larry has achieved I would have to set up a hydraulic press as he has done.
If you would like to obtain some of these superb flares, contact Larry at the address shown below, or at his e-mail address. I am sure you will be very satisfied with the results of your purchase. You may initially think that his price of $6.50, plus shipping, for a burner flare is steep, but remember that he not only makes them from stainless steel, but they are drilled and tapped, and come with two stainless set screws installed also. They are ready to just tighten into place on your burner. BTW, I get no payment of any kind for this "add." I just think that these flares meet a big need out there in the metalworking field and should be made available to the forge and foundry community. Please be aware that these flares can melt and deform if used on the Micromongo Burner when its run at high gas pressures. In the case cited in the linked document, Fred was running them at 25 psi. "
In finishing, he recommends Zoller's flares for a perfect flare.
Here's Rons new page home and extensive information. I'd like to meet this guy....
http://ronreil.abana.org/Forge1.shtml
Keep me posted on your endevors.
regards, mitch
