First Burner Build

[IgnrntNewb]

Every part of this is a first for me. My username is painfully accurate, so please feel free to educate. I'm in the process of building a propane forge using a double 'T' burner design. My aim is to insulate the forge to the extent that I'm left with as close to 700 cubic inches of interior volume

as I can get. I've included some pictures of the burners and a video. I've been researching a lot over the past few weeks, so I hope I'm on the right track.  Let me know if you see anything wrong or something I could do different/better. Thanks in advance! 

[Mikey98118]

First, those are excellent photos, and well staged to convey maximum useful information; congratulations on that.

Second, "T" burners are supposed to have smaller outlet diameters feeding into the mixing tube than the diameters of their two air inlets; this lack will cost flame heat.

Third, you still have use of a burner while you search for the right parts to replace those "" fittings with.

[IgnrntNewb]

Thank you for the reply Mikey. I was hoping either you or Frosty would chime in.

I'm not sure I understand which fittings you're recommending I replace. If you're referring to the 'T' fittings, I used T's with 1" inlets reduced to 3/4" as laid out in Frosty's instructions. The mixing tubes (again, if I understand correctly what you're referring to) are 3/4" nipple.

In case you missed it, the last "picture" is actually a video of the burners running. Am I still missing something?

Thanks again!

[Mikey98118]

I did miss the video part. I was referring to the "T" fittings, and they looked wrong, but if you got them right, I'm glad to hear of it. Off to see the video (better late than never).

[IgnrntNewb]

Excellent! If you don't mind, let me know if you see anything that doesn't look right in the video and what can be done about it.

Thank you!

[Mikey98118]

Okay, the video shows weak reducing flames, but that isn't because you made a mistake. You simply haven't finished the last step.

You need to slowly shorten their MIG contact tips, a little bit at a time, running torch tip cleaners into their orifices to clean out the internal burrs that shortening those soft copper parts inevitably cuase, to get a clean flow in their gas jets, and your burners should turn out just fine; it's called tuning the burners

 

BTW, those MIG tips look more slender than standard; what brand are the?. The voracious Mikey wants to know everything he can find out about what people use for gas jet parts

[IgnrntNewb]

Thanks again, Mikey. Roughly how much should I aim to take off the tips at a time? 1/16"? 1/8th"?

[Les L]

Use the correct sized torch tip cleaner (just slides in and push, straight) to dress them after shorting the tip. I recommend inserting the cleaner from the threaded end to ensure you don’t elongate the orifice. 

[IgnrntNewb]

I apologize. I didn't initially see your question at the end of your last response. 

[Mikey98118]

Thank you for the update.

As too tip length; it should end up being a little less than halfway across the opening diameter, but every burner is different. Even the two burners you built could end up with different MIG tip lengths; which is why Frosty calls it "tuning the burner."

If you include a video of how the flames change during tuning, that would be another excellent first for you

[Irondragon Forge ClayWorks]

Another thing when fine tuning the burners they should be installed in the forge.

[Mikey98118]

This would be a good point for Frosty to join in, since I've stumbled my way through the obvious. How about it, Frosty. Are you going to jump in and "fine tune" the discussion?

[IgnrntNewb]

1 hour ago, Mikey98118 said:

If you include a video of how the flames change during tuning, that would be another excellent first for you

Thanks again for the info, Mikey! I'm gonna do my best to remember to video the progression as I tune the burners.

31 minutes ago, Irondragon Forge & Clay said:

Another thing when fine tuning the burners they should be installed in the forge.

I'm very glad I read this before starting to trim the tips. Thanks so much!

[Half Rot Zombie]

I have a very similar burner setup that I built a few months ago. I mounted them into a helium tank that I converted then insulated with ceramic wool and a fire brick floor. Not trying to hijack your thread but after about 15 minutes of use I noticed metal dripping from the ceiling where I mounted the burners after shutting it down i realized that the bells of my burners are melting. The forge floor gets hot and the metal I'm working gets glowing pretty quickly but it has not reached a plastic state. Anyone have any idea why the outlet of the burners would be getting hotter than the steel it is aimed at? After the video attached was made I welded L brackets so I could raise and lower the burners. I wanted to build a forge capable of welding for marrying mild to hardenable steel for axe heads and eventually Damascus. Any ideas would be greatly appreciated.

[Mikey98118]

Try just running one of those burners, or cut them way back, for a tart. Then start including more insulating hard refractory between the inside of those reducers that you use for burner portals, and the flame.

[ThomasPowers]

Are the bells cast iron and so melt at a lower temp than steel?

[Half Rot Zombie]

I got them from Ferguson Plumbing Supply so most likely yes they are cast iron.

My single burner was made exactly the same as the double burners and it never melted.

[Irondragon Forge ClayWorks]

Welcome aboard Half Rot, have you read this thread? It will help you get the best out of the forum with tips like editing your profile to show your location. READ THIS FIRST

[Half Rot Zombie]

Thank you Irondragon. I did read that thread awhile back when I first found this site and I just updated my profile. I have done tons of research on forges primarily gas fed. I just haven't been able to locate any information regarding the burner melting. My last forge I built was all firebrick and a singe burner. I have over 100 hours easily and although the bell would get hot it never entered a liquid state. I built this double burner for higher heat applications but the burners reach melting point before the metal in the forge reaches a welding heat. I will add pictures shortly to show what I have done since the video that I posted.

[Half Rot Zombie]

I am running .35 welding tips but read that .23 - .25 is better for the type of burner that I built so I bought some today and tomorrow I will install and see if that makes a difference.

[Frosty]

On 12/3/2019 at 1:19 PM, IgnrntNewb said:

Excellent! If you don't mind, let me know if you see anything that doesn't look right in the video and what can be done about it.

Thank you!

I just saw this thread, sorry I'm late in. Mike and IDF&C have covered things pretty well. I only have a couple things to add at this point:

First trimming the mig contact tip Jets increases the amount of air the burner entrains. The farther from the mixing tube "Throat" the more air it will entrain. I trim in small increments, I think you can start with 1/16" for the first one. From there on 1/32" or less till you have a neutral flame.

Secondly, I believe the fittings Mike was referring to replacing are the extra ones on the gas supply lines on top of the burners. Put your gauge and 1/4 turn shut off valve on the regulator, this is where you will be standing when you adjust the PSI and if something goes badly wrong say a hose burns through and starts burning you want to be as far from an out of control gas fire as possible. Yes?

You can use iron fittings for the propane supply, they're cheaper and stronger, for a win win. You have it plumbed in brass so don't go spending more money at this point. Brass isn't wrong it's just more money than necessary, a little propane rated pipe dope or tape on the threads and you're golden with either type. Yes?

I love your pics and video, excellent lighting and framing. I'm no fan of videos but darn it all, your's show things stills don't plus I can hear the burners note. Mike and I see different things in the flame but we reach the same results. As he says your burners are running rich but that's just a matter of tuning the jets. The thing I saw was an excellent example of why I don't thing bell reducers made good outlet flares, or (flame retention nozzles.)

When you look at the flames, you'll see they're beautifully centered and the shape is good for being rich. However they are the same diameter as they would be exiting the mixing tube without a flare. This tells me the bell reducers are having little if any effect on burner performance.

I'm not suggesting you remove or change the flares, your burners are working well and only need a little tuning. I'm only bringing it up as an example of why I don't like bell reducer flares.

Mount those beauties in your forge and tune them up. You've done good job, they'll rock your forge.

Frosty The Lucky.

 

[G-son]

1 hour ago, Frosty said:

...trimming the mig contact tip Jets increases the amount of air the burner entrains. The farther from the mixing tube "Throat" the more air it will entrain...

This is a matter of getting the end of the gas jet in the right place in the burner to get the correct air flow, right? A different construction where the gas jet can be moved in/out could be used for the same result, or am I understanding the function wrong?

[Frosty]

Let's see if I waited long enough my response to you Half Rot Zombie or HRZ if you don't mind, wouldn't get merged with my last. I didn't want to confuse things as your burners have problems the last post didn't.

I need a couple details to form a firmish opinion. 1. How long are the mixing tubes? 2. how do you have the jets mounted? 

Without details I can make a couple educated guesses. The first and loudest red flag I see is the length of your mixing tubes and where you've mounted the burners.

The proper ratio for mixing tube length to diameter is 8:1 meaning the length should be 8x as long as the ID. Making a 3/4" diameter mixing tube 6" long. It's not critical or I'd be measuring pipe nipples every time I built one. Assuming the pipe nipple is as stated is safe enough.

Anyway, your burner tube should be 6" long.

You welded the bell reducers to the shell. This is outright bad. First is my opinion of bell reducer burner flares as I said in the above post. They are too abrupt a transition and as seen in the above post the flame burns INSIDE the bell reducer. Add to that the thickness of your forge shell to capture and hold the heat.

These two things make the inside of your burner and burner ports the hot spots in your forge!

I don't know what you have available for shop tools but if you have a drill press I highly recommend you put the welder away when making burner, it's NOT helping you. If you use a drill press as I laid out in the illustrated burner directions thread, drilling and tapping dead straight is easy. Forget about finding the bras fittings I recommended in the original plans, it's getting harder and harder to find one with the right ID to tap for the mig contact tips.

Use 1/8" scd. 80 pipe nipples instead, the ID is almost perfect to tap to match the threads in the mig tips you have available to you. Don't assume they'll be what I said in the instructions, things have changed. There are several potential threads and pitches used for mig tips and guns so go to a REAL welding supply ad ask for their chasing kit. Mig gun threads are always getting messed up, usually caused by the wire melting the contact tip and needing some brute force to get out which tends to be hard on threads. This makes needing to chase them pretty common. Anyway, the guys at the counter can sell you the correct tap at the counter and probably have the correct pilot drill to go with. If so GET ONE, at least one! That way if the scd 80 pipe nipple is a little too wonky to tap you can chase it first then it's easy as eating pudding. Yes?

If you want to use a bell reducer for a burner flare get the LEAST diameter change you can find! If you can find a 3/4" x 1" get them, get spares. Tuned properly a burner flare or flame retention nozzle isn't necessary though a good one will improve performance. . . SOME. They just do NOT make a significant improvement, help yes, must have, no. I don't run flares on my Ts at all, I put a thread protector on the ends to make them easier to mount. There's a SLIGHT difference in how I trim the Jets (contact tip) to account for having a thread protector or not. 

Okay, assuming you've rebuilt your burners mount them with the ends just inside the refractory. If you've ditched the way big bell reducers then the burner ports through the refractory layers will act as a proper burner flare and the flame will impart it's energy to your forge liner rather than the burner itself. If you reshape the burner ports by first rigidizing the refractory blanket thoroughly and curing it, then applying a water setting hard refractory you can shape the refractory to a 1:12 increasing ratio flare. A last coat of a good kiln wash and Bob's your Uncle.

As a last note about how I mount burners on a cylindrical forge, I position and align them where I like and weld an piece of angle iron to the shell and clamp my burners to it. It allows me to adjust for depth easy as unclamp, slide, reclamp. Anymore though I'm liking the sleeve mounts the guys are using, they allow a broader choice of adjustments for a reasonable increase in hassle building. 

Give a shout if I haven't been confusing enough, I'll gladly try to muddy the waters further. 

Frosty The Lucky.

4 hours ago, G-son said:

5 hours ago, Frosty said:

...trimming the mig contact tip Jets increases the amount of air the burner entrains. The farther from the mixing tube "Throat" the more air it will entrain...

This is a matter of getting the end of the gas jet in the right place in the burner to get the correct air flow, right? A different construction where the gas jet can be moved in/out could be used for the same result, or am I understanding the function wrong?

You got it, that's exactly right. Just remember the really important thing is keeping the gas jet aimed as close to the center of the mixing tube as possible. Folks who don't understand this and mount their jets at or even in the mixing tube MUST use smaller higher velocity jets to entrain enough air to be neutral. Knowing this basic thing about induction devices is why I can put 0.035 contact jets in mine where other folks are swearing and sweating trying to get one to work with 0.025 or smaller jets. 

Frosty The Lucky.

[IgnrntNewb]

9 hours ago, Frosty said:

The thing I saw was an excellent example of why I don't thing bell reducers made good outlet flares, or (flame retention nozzles.)

When you look at the flames, you'll see they're beautifully centered and the shape is good for being rich. However they are the same diameter as they would be exiting the mixing tube without a flare. This tells me the bell reducers are having little if any effect on burner performance.

Frosty The Lucky.

 

Thank you very much for your response. I see what you're saying about moving the gauge and shut-off valve back to the tank. Makes perfect sense to keep it further from the heat. I'll make that happen.

I read in your instructions about bell reducers not being ideal, but I was unable to find the thread protectors you mentioned. All the suppliers around here just use plastic thread protectors. Do you have a link where I could get some 1/2" black steel thread protectors, or maybe some pretty stainless steel units? I'd like to do this as correctly as possible, and even if my bell reducers aren't technically "wrong", I'd still rather do it the way the guy that designed these burners recommends...

Thanks again!

[Half Rot Zombie]

Thank you Frosty, the burner were temporarily tack welded for testing. The attached images might clear up a few things but if not here are the specs I built the forge burners to. 1x1x3/4 tee, .035 welding tip, 8 in x 3/4 down pipe and 3/4 to 1 1/4 bell reducer. I welded on some L brackets and purchased some stainless steel clamps to adjust height of the burners. As for how I mounted the jets, the I welded a nut to the end of a 3 in nipple that is the same size and pitch of a welding tip then drilled a hole in the center of the tee and welded it in. I had to sell my drill press when I moved out of state but I do have taps and dies. The Shell is from an old helium tank lined with an off brand of isowool that doesn't require rigidizer. I have a tub of refractory cement to coat the inside but I have not done it yet.