Gas Forge and Burner- what is wrong?

[Moose65]

The burners 101 and other threads have been great! I wouldn't! Be where I am without them. But I need a little more help. I have built a DIY gas forge out of an old air tank. I have installed the ins wool and refractory cement. I am on my fourth build of jet burners and have read and drill enough to make a block of Swiss cheese. I am closer but still not happy with the bouncing blue flame. The mixing chamber is 3/4" and about 7" long from the first breather hole to the threaded flare. My holes are about four 1/4" and four 3/8". All just behind the 0.30 welding nozzle. I started with two holes and progressed until I had added up to eight and then bored out four to 3/8". I do not desire more holes. It has improved but I feel there is room for improvement. Thanks in advance. Moose.

IMG_0130.mov

IMG_0129.mov

IMG_0131.MOV

[Moose65]

I did attach three videos but if they cannot be viewed they show the blue flame bouncing away from the flared ends. Any advice would be appreciated.

[TFT]

Without seeing the thing its gonna be hard to give advice but with that style of burner try slots instead of holes with a choke tube.... i have a burner that probably looks very similar with a bunch of holes but it was limited and i moved on to a venturi so i have made one with the slots

If you look real carefully you can see all the holes behind the hammer and the pipe is like swiss cheese and the choke does nothing but reduce heat

[Moose65]

Ok I did post three videos in .mov format. I will see if I can post a picture. I almost tried slots. I was thinking slots at an angle to let the air enter as a swirl.

Thank you for the assistance. My blue flame is bouncing up and down in the forge. It does heat but the bouncing is not optimal. I am attempting to attach some pics of the video showing the flame at different locations so you get the idea. I also took a pic of the missing tube. I do not have a choke installed.

[TFT]

Wow thats a massive forge... i know i had some issues (Perhaps bouncey) with my crappy flares, as i have tried to machine a few... maybe its your flare what is it and or pics heres my air intake..

Alot of holes 

[wpearson]

Notice the different placement of the gas jet ?

[TFT]

27 minutes ago, wpearson said:

Notice the different placement of the gas jet ?

Yea i didnt even pay attention to his jet all tucked in there

[Latticino]

I may be totally off base, as I haven't seen the video, but from the photos I'm seeing a couple of questionable things:

1. Looks like your flame is detaching from the front of your burner. As I understand it that means the gas/air mixture is moving too fast for the size of your burner outlet. If the mixture has the correct proportion, and I can't tell that from the photo, then you need less of each. If not enough air is being induced and mixed with the gas then you most likely need to increase the gas velocity with a smaller diameter orifice and position it properly. I'mnot that familiar with the burner design you are using. Perhaps you should contact the designer for advice? It takes a lot of time and experimentation to get a well tuned NA burner to work well. If this is your own design, be prepared to put in the work to get it right.
2. How thick and what insulation have you used for your forge? Looks thin to me, but hard to tell
3. I sure hope you removed the doors to show us the flame. Otherwise you are fighting a losing battle with those huge openings

[TFT]

7 minutes ago, Latticino said:

 

1. How thick and what insulation have you used for your forge? Looks thin to me, but hard to tell
2. I sure hope you removed the doors to show us the flame. Otherwise you are fighting a losing battle with those huge openings

I was thinking the same thing

 

And Moose, try those angled slots tell us how that goes, may have to steal that idea if it turns out... but i wanna see the flare/nozzle

[Frosty]

Are you guys following anybody's plans? Both your burners are running darned rich. Moose your burner is extremely rich that's why it's fluttering. Did you calculate the volume of the forge and determine what size or how many burners to use?

I recommend you look around, find a reliable set of plans and follow them. Forget what some person on the internet says he got to work. Don't look all over the place for help, you'll get sage advice from kids who haven't figured out how to make one work yet.

A set of plans for a forge aren't a bad idea either, there are ratios regarding volume, shape, opening size and placement, burner number and alignment, hot face liner, insulating backer and kiln washes. All these factors effect how or even IF a forge will work efficiently. After you get a handle on what these factors mean and how they effect performance is a good time to decide what yo MIGHT need to make what you wish to make.

Frosty The Lucky.

[Moose65]

4 hours ago, TFT said:

Wow thats a massive forge... i know i had some issues (Perhaps bouncey) with my crappy flares, as i have tried to machine a few... maybe its your flare what is it and or pics heres my air intake..

Alot of holes 

The forge an from one of those portable air tanks. A little larger than a propane tank in length by 8" or so. The burner I followed online had the tip forward. I did try one with tip at the rear holes, actually the first one I built the tip was at rear, and it was always too lean. No blue flame. Even with many orifaces. I may have to try it again.

2 hours ago, Latticino said:

I may be totally off base, as I haven't seen the video, but from the photos I'm seeing a couple of questionable things:

1. Looks like your flame is detaching from the front of your burner. As I understand it that means the gas/air mixture is moving too fast for the size of your burner outlet. If the mixture has the correct proportion, and I can't tell that from the photo, then you need less of each. If not enough air is being induced and mixed with the gas then you most likely need to increase the gas velocity with a smaller diameter orifice and position it properly. I'mnot that familiar with the burner design you are using. Perhaps you should contact the designer for advice? It takes a lot of time and experimentation to get a well tuned NA burner to work well. If this is your own design, be prepared to put in the work to get it right.
2. How thick and what insulation have you used for your forge? Looks thin to me, but hard to tell
3. I sure hope you removed the doors to show us the flame. Otherwise you are fighting a losing battle with those huge openings

Thank you for the reply. The flame does bounce back and forth. I have a 0.30 tip, the smallest I could find in my shop. I may try a 0.25 because that is the easiest fix. I place the tip forward after viewing a burner design like mine on the web. However my first design was the tip to the rear and it was worse than this one. This one actually stays lit and heats metal but flame bounces and I know that is not optimal.

The insulation is one inch ins wool coated with Satinite. Then I layer fire bricks in the bottom. It probably could have used two inches of ins wool. But believe me the forge gets hot, very hot.

Yes the doors the big doors are open on both ends.

[Moose65]

14 minutes ago, Frosty said:

Are you guys following anybody's plans? Both your burners are running darned rich. Moose your burner is extremely rich that's why it's fluttering. Did you calculate the volume of the forge and determine what size or how many burners to use?

I recommend you look around, find a reliable set of plans and follow them. Forget what some person on the internet says he got to work. Don't look all over the place for help, you'll get sage advice from kids who haven't figured out how to make one work yet.

A set of plans for a forge aren't a bad idea either, there are ratios regarding volume, shape, opening size and placement, burner number and alignment, hot face liner, insulating backer and kiln washes. All these factors effect how or even IF a forge will work efficiently. After you get a handle on what these factors mean and how they effect performance is a good time to decide what yo MIGHT need to make what you wish to make.

Frosty The Lucky.

Yes I agree now. I read, I believe in BURNER 101 thread, that one 3/4" burner could heat 350 cu in. Well I have about 5000 for two burners. So might have screwed the pooch on that calc.

I measured out the burners from the threads for the flare to the nozzle as about 7".

the flares are just 3/4" brass with smooth brazing Tip of 1" ID. Just me using what I had.

if it is two rich that means too much propane? I added holes until I got a blue flame and not a yellow flame. I stopped because I felt it was going over 40% of id of mixing tube.

I actually can heat metal now but not efficiently

Thank you in advance. 

[TFT]

31 minutes ago, Frosty said:

Are you guys following anybody's plans? Both your burners are running darned rich. Moose your burner is extremely rich that's why it's fluttering. Did you calculate the volume of the forge and determine what size or how many burners to use?

I recommend you look around, find a reliable set of plans and follow them. Forget what some person on the internet says he got to work. Don't look all over the place for help, you'll get sage advice from kids who haven't figured out how to make one work yet.

Hey man im just trying to help him out

But i thought my burner was running good... can you show me what an ideal flame should look(for real i thought mine was good and now im lost)

 

[Moose65]

Thanks for all the help. I believe a true diy project involves trial and error. That is why I do it. I appreciate everyone's help. Sure send those plans on over. I'll be glad see them. Thank you.

[Frosty]

Yeah, you might be off a skosh on the burner chamber ratio.

I need to see a pic of your burner, I don't get your description, it's a terminology thing no biggy. This should give you a better idea of a simple to build burner that works well. http://www.iforgeiron.com/topic/43976-t-burner-illustrated-directions/

There are a number of good designs. (I always feel presumptious calling the T burner a "design but what the hey) The T doesn't require more than basic shop skills and a drill press to build. Mike Porter's burners are much more efficient and if you have good shop skills I can't recommend a better home build.

Gun (blown) burners are a different thing though there isn't any real fundamental difference, both types shove the correct ratio of air and fuel in the forge. Guns are easier to make but are tied to electricity and are a little fussier to operate. Neither is a serious factor.

TFT: SORRY man, I didn't mean you are the "some person on the internet". I apologize sincerely I should've re-read before posting it's my bad. The flame from your burner is opaque light blue the outer burn zone is transparent dark blue and feathery. My burners have the pale opaque primary flame but it's shorter and more conical, the dark transparent envelope is also tighter. You can't hold a conversation around my burner without yelling at each other It roars unpleasantly.

However, since Mike's been posting here I've started changing my evaluation of burner flames, especially with his thoughts on how a forge should be built. You can get away with a neutral flame meaning it should be transparent blue with no pale cone or primary flame.

My burners run a LITTLE rich on purpose to prevent scaling in the forge. However if Mike's right about forge design and baffles I'll be leaning mine out considerably. He's also convinced me round air intake ports in a naturally aspirated burner aren't the way to go.

Frosty The Lucky.

[TFT]

Hey frosty no big deal i am kinda just some guy but i figured id take the weight off you non-rookies and i shouldnt have im sorry but im terrible with words and description terms on the flame could you show us a pic of your t burner, in action, cause i made two(different tee sizes and they have a mount that holds on to a sliding brass tube) and it didnt seem much different from my others, ill have to look more closely i suppose and i know its a bad thing to modify your design but i figured i could tune it quicker

[Moose65]

I viewed the T burner design and opted to try the jet burner instead. Would it help if I added a choke tube and gave that a go and also with smaller orifaces on nozzles?

[TFT]

Jet burner? Link please

[Moose65]

https://youtu.be/VxzdqcPzXj8

His was one of the basic designs I saw. Not necessarily my design. I'm not a fan of the t burner but I may have to change. I still don't feel I am far off bass with mine. I will try and get more pictures tomorrow.

[TFT]

Yea that burner has maybe bigger holes in it but at least closer together and a far back jet like you said you tried

[Moose65]

Ok tomorrow I will experiment with jet at the rear and holes forward. I have some 3/4" and a threading machine. What size holes and how many initially? 

[TFT]

Try it just like his i suppose and mine isnt the best example but i think two long slots with the choke (mikey burner i think) is your best bet

[Mikey98118]

If your burners were anywhere near close to right, the size of the forge would barely effect them. Nor are burner air holes causing your present trouble. The gas and air are are leaving the burner faster than the flame can burn back to them, because your flame nozzles are ineffectual. Once you put proper nozzles in their place it will be time to see to your burner's hole problems, which are going to limit their outputs to pretty weak. Why should that be? Because you not only choose holes over rectangles, but then drilled way too many of them

 

[Moose65]

Update. Well I had a little time to make it to the shop and try some of your suggestions. Installing the .025 tips, cutting and threading a new 6 3/4" mixing tube, drilling 3/8" holes in front of the nozzle tip instead of behind it, and adjusting down the gate valve and regulator allowed the blue flame tray steady on the flares. There is a slight roar but not as load and hot as I would like. But all of these gave improvement. When I turn up the regulator the flame separates and jumps.

i also took Frosty's advice and built a couple of "t" bu nets. I had to make do with what was at shop and ran out of time. I didn't cut down the 10" mixing tubes or got the nozzle tips the correct distance from the mixing tube but I will give the "t" burners a go. 

I am attaching more pics so you all can see the build. I will be adding more Satinite but not sure if I can lay ins wool on top of last Satinite layer any advice recommended please. 

I am aware of the large doors. So far I keep one end shut and use the other door as needed. I may cut a rectangle 3x5" hole in one end.

Thank you all for your support. This build has been a learning experience and he'll I don't even know what I will be forging but I hope to make a set of tongs first. I sure could use them already.

[Frosty]

Dave Hammer's burners work okay. I like his shop technique but as built his burners are pretty low performance. He gets a neutral burn by using a small jet diameter, 0.025" mig contact tip in a 3/4" dia tube, with more than enough air intake ports. This makes an inducer that draws way more air than needed for a neutral burn then he puts a choke on it so it can be adjusted.

I run a 0.035" mig contact tip in a 3/4" burner but tuned so it doesn't have choke. A 0.35" jet puts well more than 2x the propane in the burner than a 0.025" jet at the same pressure.

Looking at the T burner pic looking in the air port tells me that burner runs darned rich. Was I unclear in the directions about tuning the burner by trimming the length of the mig tip? The T needs the tip of the jet less than half way to the tube. Looking straight in the air port the end of the mig tip should be above half way. Start there and trim it back in SMALL increments till it's burning clean. Buy a torch cleaning file set and use something fine to cut the tip. I like chucking the mig tip in a drill motor and using a Dremmel cutting disk to cut the contact tips. Then I deburr it with the torch files pushed from the threaded end of the mig tip.

Was I unclear about how long to make the tube in relation to it's diameter? 8X the diameter makes a 3/4" tube 6" long, you can get away with a LITTLE longer but around 7" and you have to start using undersized jets to overcome the friction blowing down the tube.

Part of the reason the flame travels so far and is fluttery is because it's so rich it can't burn near the burner nozzle there isn't enough oxygen. Mike isn't actually wrong, he's just not used to looking at T burners in distress.

Frosty The Lucky.