SteelRiddler Posted April 4, 2020 Share Posted April 4, 2020 Hi Guys, I have been reading this forum for a long time and decided to follow suite and build my own gas forge. I wanted input from some who have them on proper flame adjustment and a question about my plenum. As for the forge, it is 18 deep by 9 across, a 100 lb propane tank that i cut. 2 -1 inch layers of inswool rigidized and lined with kastolite 30. The floor is greencast 94 and I also applied an ir coating over the entire area except the burner. The burner is the typical wayne coe- john emmerling posting, 12 inches by 3 inches made of mizzou. Its a little big but I intend to use it for heating large stock and working axe heads. I have posted a couple of pics of it for you to see. The concern I have is that the plenum is getting pretty warm. I did not seal the inside of it with any wool after inserting it but i did pack the outer box holding the burner. Should i Insulate it on the inside? I have not had any flash backs but the warm plenum is concerning to me. My last run was with the ball valve open 1 turn and the needle valve open about 3/4 turn. I can blow the flame off the ribbon no problem so I think I have enough air. Suggestions? Also, today as I turned up the air a bit I was getting a loud hum? Thanks for looking and any comments are welcomed. Link to comment Share on other sites More sharing options...
SteelRiddler Posted April 6, 2020 Author Share Posted April 6, 2020 Well today i removed the gas inlet pipe and turned on the blower. it seems i have a good bit of air coming back out the inlet hole, maybe my holes in the ribbon are not big enough. I did go ahead and add an orifice to the inlet and now i dont have any air blowing out but I still have too much velocity at the ribbon. I can hardly open the air gate valve or its too much and blows the flame off a good bit. I used drinking straws for the mold so maybe I will open them up a little and see if that eases the restriction. Link to comment Share on other sites More sharing options...
Frosty Posted April 7, 2020 Share Posted April 7, 2020 What did removing the gas line from the jet tell you other than the static pressure developed by the blower is greater than ambient and less than delivered through the needle valve? The plenum is getting pretty warm? What's pretty warm, mean? Can you touch it or is it glowing in the dark? Is it as hot behind the diffuser? What IR coating did you use and why not on the burner block? The less heat the burner block absorbs the cooler it all stays. No? The NARBs get hot enough you can't touch them more than a second or so but they don't get so hot as to start preigniting. (burning back) How does it work when you turn down the air and gas? I can't see the dragon's breath from the pic's angles but I don't much like how far off the orifices the flames are. Though I believe that's a characteristic of John's design. Frosty The Lucky. Link to comment Share on other sites More sharing options...
SteelRiddler Posted April 7, 2020 Author Share Posted April 7, 2020 Thank you sir for the reply. Being new to gas forges I’m not sure of anything to be honest. The plenum top gets warm enough that I do not want to leave my hand there but I can tap touch it at any time. I’m not sure how hot it should be or if at all. The static pressure of the air in the line lead me to think I needed an orifice or that my exit holes in the block were too small. Is a lot of pressure a good thing? I’m using a small bounce house blower. I had what I thought was my best run with the air gate valve open 1 turn from close. I don’t know if that is enough air moving or not. The needle valve was open 3/4 to 1 turn and I had 10 lbs of pressure from the tank I used 900r coating and why I didn’t coat the burner head now baffles me too. I will certainly do that. Any idea of what the loud whooing sound might be coming from? I appreciate your time. Link to comment Share on other sites More sharing options...
SteelRiddler Posted April 7, 2020 Author Share Posted April 7, 2020 Well I ran the forge today and got it to settle down. The plenum gets about as warm as the forge outer shell but it does not glow and i have no backfiring. Still learning the curve on adjusting the flame. I suppose I am close here in the pic. The only unknown I seem to have at this point is that when I get the air or gas out of adjustment I get a harmonic train horn like sound but if I adjust the air or fuel again it goes away. Maybe just part of John's design. I listed 900r as the ir lining but it is plistix 900f. Link to comment Share on other sites More sharing options...
Frosty Posted April 7, 2020 Share Posted April 7, 2020 Your plenum isn't overheating then, it's good. It takes some playing with, you'll learn to make it do what you want. This flame in this pic is a little rich. The orange dragon's breath is typicall of most calcite bonded refractories and not the indicator it is some places. A while back there was quite a discussion about some of the sounds ribbon burners can make. I made a guess but it wasn't so much THE cause, just why the "cause" was making noise in one instance. It was a guess even if it made some sense. If you put a brick laid flat in the doorway to act as a sill it'll keep more flame and heat in the forge. Frosty The Lucky. Link to comment Share on other sites More sharing options...
SteelRiddler Posted April 7, 2020 Author Share Posted April 7, 2020 Thank you sir for your input. It offers me hope! Link to comment Share on other sites More sharing options...
Frosty Posted April 8, 2020 Share Posted April 8, 2020 You're welcome, it's my pleasure. There's hope for anyone wanting to be a blacksmith. Just be patient, it'll come and we'll help. Frosty The Lucky. Link to comment Share on other sites More sharing options...
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