CactusBob

T burner tuning question

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Its been a few months since I have been able to run my Freon tank forge. With temps over 100 and an outdoor work area with no shade, its just no fun. The burner is a 1/2 in TEE with the flame looking like the pic. I had a 3/8ths piece of rebar that would only get to an orange heat after 15 to 20 min at about 10-15 psi. The back of the forge is almost closed and its about 150-200 cu in. Does this just need the tip shortened a little more, or did I go to far? Or could it be something else entirely?

1117181847.jpg

1117181855c.jpg

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4 hours ago, Mikey98118 said:

The MIG tip isn't aligned with the burner axis. The burner also appears to be kinda short.

What mikey said, Also for a 1/2" T burner, your Tee should have a 3/4"x3/4" run with a 1/2" branch

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I will double check the axis of the tip, I thought this one was straight, it is a lousy picture. I will pick up another tee tomorrow and fire up the drill press

the tee is a 3/4 run by 1/2" chase and has a 4 1/2" nipple. It is sitting so its about 1/2 to 1" from the inside of the burn chamber. Should this be pulled back further?

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If you look, the burner's "T" casting isn't square at its lip; if you placed that lip on the drill table its hole would end up out of line with the casting's axis. Instead, you need to use the internal thread to line the hole up with the casting's axis. a short pipe nipple and a floor fitting will make that easy. It is common to see castings that are out of square, while it is usual to find the threading on those same castings to be properly aligned.

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I know I'm new here but I'm going to comment and say that it is definitely an alignment issue. My burner is a Ron Riel inspired  burner, but similar by design and if I rock my tip out of center, I get that same blue flame. I messed with it today and changed tips from .023 - .035 and position to tune it and found that the smaller tip made a smaller flame that took longer to heat up the forge. Once I put in the .030 tip and centered it, with my flare flush with the ceiling, I had a very hot and almost neutral flame. I have to run my regulator at almost 45psi to get a good, hot burn even though it will heat up at 15-20 psi,  it takes forever. Truth be told, an .030 Lincoln mig tip is actually closer to .040 and yes I tested the whole pack. Just keep messing with it and listen to the guys above and most likely, below this post. 

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I picked up a new 3/4r X 1/wc tee today along with the new parts to rebuild the jet. I will have to wait on pics until tonight. I'm also getting some new mug tips so I can change that if necessary. The hole and threads for the brass fitting and mug tip were done while on the drill press. I don't know if I can get them straighter. Here's how it looks.its a lousy pic, I will try to get a better one later. The forge is still only heating to orange

Bob

 

2018-11-24 15.27.28.jpg

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I was able to get some pictures of the forge running

here are two shots of it running at about 5psi or so this was shortly after lighting 

1124181814a

and

https://flic.kr/p/2dbos2B

This is about 10 psi

10psi

Here is two short videos the first at 5 psi and the second at 10 psi

https://flic.kr/p/2dbos9F

https://flic.kr/p/2apUTtJ

I am still only getting to an orange heat, I can go from cold 3/8 rebar to orange in about 5 min but it doesn't get hotter

Burner is 3/4r X 1/2C reducing tee, .023 mig tip (the new ones I just bought but haven't used say .024) 1/2 X 4in nipple set so the end is just inside the forge shell. The back of the forge is mostly closed with an insulating firebrick.

Hopefully this is an simple fix, I would like to get to welding temps if possible

 

Bob

 

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I'm not sure why you're getting those results, but from what I can see and hear there isn't nearly enough air being drawn in with the fuel.  At 10 psi that burner should sound almost like a small rocket engine.  Is there anything that decreases the diameter of the mixing tube or restricts the flow in the tube between the T and the end?  I would suggest you try a smaller mig tip, but if you're already using a .023 tip I don't think there's anything smaller that is commonly available.  In the second video is the flame holding at the end of the mixing tube?  I couldn't tell for sure.  It kind of looks like the flame has blown off the end and all of the combustion is happening away from the burner tube.

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I will check the flame tonight and see if I can tell where it is. Where should it be, hanging right at the end of the tube?

There is nothing stopping the airflow unless its the exhaust from the forge? Maybe?

Should there be a lip from where the tube is cut or should that be smoothed out?

Thanks

Bob

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The flame should be holding steady at the end of the burner tube or flare.  I don't think the exhaust from the forge could produce that pronounced of an effect, but I've been wrong before.  It's best not to have anything that can slow down the flow of the fuel/air mixture in the tube.  If there is a lip it would probably be best to remove it, but it still seems odd to me.  You aren't using schedule 80 pipe for the mixing tube by any chance are you?

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Is there a gap where your burner goes through into your forge? I'm talking between your burner and your mount. If there is air coming in around the burner, it will do this as well. I just stuffed some kaowool between my burner and my mount to stop it. Just talking out loud at this point.

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He said it's a 1/2 inch burner with a 4 inch mixing tube.  I personally use 4.5 inches, but do you think that half inch would make that much of a difference?

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Off hand, no; I would only consider it to be a contributing factor, But the burner is heavily reducing, In this case I would go for a little overlong--not under long. This is an easy change; the only one that will be. It could improve the flame enough to encourage him to make the other needed changes. Over the last twenty years I have found discouragement to be the biggest stumbling block for builders at this point.

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On the other hand the change that will do him the most good, drilling a second "T" fitting dead center, is also going to be the hardest for him to do. Some cheap and easy improvement in performance is a good move, even if that improvement will be minimal.

When he has taken the big step of drilling another "T" fitting, burner performance will improve more, but his patience is more likely than not to be stressed by the need to replace the MIG tip with a longer one, and then cut it back a little at a time to properly tune the burner, so every bit of encouragement he gets along the way will probably be sorely needed :rolleyes:

My burners have completely different flow characteristics, and so they have very different tuning headaches, but they are also a trial for a beginner's patience. It is easy for us expert types to see how to fix what is wrong, but hard to remember back to our own hand wringing moments; were we ever that young? You bet we sure enough were :unsure:

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I have a 4.5 in tube so that is, as Mikey said an easy fix. This one was drilled connected to a floor flange clamped to my drill press table for the drilling and tapping. I screwed the tee off and put the 1/8 mpt fitting in upside down to thread that as well, does this one look off as well? Also is there something else I could do to get it straighter?

There are small gaps between the burner mount and shell from where I cut the pipe and bent it out and screwed it to the shell, should those be sealed?

I have a package of mig tips so if this one needs to be longer then that is also an easy fix.

The encouragement, help and advice from you folks is more than enough to keep me going.

Thank you for your help

Bob

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1 hour ago, CactusBob said:

This one was drilled connected to a floor flange clamped to my drill press table for the drilling and tapping. I screwed the tee off and put the 1/8 mpt fitting in upside down to thread that as well, does this one look off as well? Also is there something else I could do to get it straighter?

The gas jet in the photo still doesn't look centered; there is no practical way to make that right, which doesn't mean it can't be improved somewhat. You already know that you must replace the MIG contact tip with a longer one, which can be gradually shortened in order to tune the burner for best performance; this is needed because the tip is already likely to be too short to begin with.

Before shortening the tip, you have an opportunity to bend it a little bit to make the the gas stream closer to central with the mixing tube's axis. This is less than an ideal solution to the problem, but could make a lot of improvement.

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I should have added that the second try doesn't seem to be as far off center, which is why a little bending of the MIG tip could improve performance a lot.

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You have a very good eye, I just came back in from looking at it and yes it is off, I didn't notice until I put a new mig tip in it and although it is even across the width of the tee it is off on the length by about 1/2 a mig tip, so yes a new tee is in my future, along with a better ruler or getting my eyes calibrated. I'm not quite sure how I was off on that direction. The pic trys to show what I mean, if it makes sense.

I did put the 4 1/2 nipple in and with a new mig tip and even though it was off it was getting hotter than it had before. I also moved the tube closer to the edge of the shell and it started roaring more than it had been, enough so the roar covered the sound of air going in the tube. I will try to post the pictures tomorrow after I get them off my phone.

Thanks again for your help

Bob

pipetee.png

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Since it is off in that direction, rather than being drilled at an angle to the mixing tube, there is an easy fix. Simply drill a pilot hole in the center (where the first hole shouled have bee}, and then enlarge it so that you end up with a slot instead of an off center hole.  Because you have a nut inside as well as outside the pipe fitting, you should be able to center your MIG tip, and go on with cutting back a little bit at a time.

Remember that copper, being very soft, is inclined to create burrs inside the tip when it is shortened; therefore, don't even begin trying to fine tune the burner without having a set of torch tip cleaners on hand.

Also, once you get to fine tuning your burner, try to get Frosty to guide your effort. This is his burner design, and he is the expert; not me.

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Would an overly long tube create enough draft such that the burner would naturally run lean? Having some grief getting mine to run rich so I can even start trimming the mig tip back. 

Thanks,

Al

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10 hours ago, Mikey98118 said:

which can be gradually shortened in order to tune the burner for best performance; this is needed because the tip is already likely to be too short to begin with.

To my eye his burner is running extremely fuel rich.  Shortening the mig tip should lean out the mix a little.  However, if he's burning very rich with a short mig tip I'm not understanding how replacing it with a longer tip and then trimming it back will help.

1 hour ago, Gippeto said:

Would an overly long tube create enough draft such that the burner would naturally run lean? Having some grief getting mine to run rich so I can even start trimming the mig tip back. 

The easiest thing to do here is move up one size in mig tips to see if that will get you running on the rich side.  If it does then you can start to trim it back.  That will have a much more profound impact on the fuel to air ratio than changing the mixing tube length a little.

 

12 hours ago, CactusBob said:

There are small gaps between the burner mount and shell from where I cut the pipe and bent it out and screwed it to the shell, should those be sealed?

In your case the gaps will probably only help since that allows more outside air to be drawn into the forge (potentially) which would help with your fuel to air ratio.  I'd focus on getting the burner running right before worrying about those gaps.

One way to check if your mig tip is centered is to use pressurized water (a garden hose should suffice) and connect it to your gas fitting at the T.  You can then observe the water stream in relation to the mixing tube walls to see if you are centered well.

Also, earlier I asked if you were using schedule 80 pipe for your mixing tube.  If you are then that will have significantly decreased the inner diameter of the mixing tube compared to what it should be and that would tend to make you run very rich.  Schedule 40 (which is "normal" water pipe) is what you want to use here if you aren't already.

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