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Interesting Venturi style burner


Firestorm102389

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So I’ve been looking up a lot of Venturi style burners, and I came along an interesting one where the gas injection is up above the air inlet. I saw this one:

however, with these style, which I really love the air adjustment and overall look and how stupid easy it would be to make, it’s missing the flare on the upper portion. Could I get some insight from some experienced members on something like this?

im new to the forum, so hi btw. 7 year professional welder here, just looking to get into forging to try it out and I love making stuff. Working on my first forge, got the whole thing planned out how I wanted it based on stuff I found in here and elsewhere using a 20# propane tank. Decided 2 burners, however I just didn’t know what style to go with and these seem to be the least headache , I hate messing with fittings and adapters. These seem to be easy enough to make and set up for whatever fittings I want. 
 

it’s similar to the T. rex burner except that Bell before the Venturi is missing. I’m thinking of it more like a carburetor and feel it should have one but if it can work really well without, I’d be interesting in hearing input. 
 

thanks in advance. 

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Welcome aboard Firestorm, glad to have you. If you put your general location in the header you'll have a chance of hooking up with members living within visiting distance.

If you have moderate or better shop skills Mikes later designs work even better than this old workhorse design.

Frosty The Lucky.

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1 hour ago, Mikey98118 said:

You can find all the answers you're looking for in the Burners 101 thread. So says the guy who invented the burner design you are trying to make.

I did, start there, there’s 93 pages so I’m taking it in sections, you’ll have to excuse my adhd. 
however, I did not know they were called Mikey burners, so that lends a hand to me to look up things further. He actually has a modified one he explains in a YouTube video. I think What I’m going to do is just make a modified sidearm set of burners to start, just because I can whip them up quick, and the modified Mikey burner is gonna be a bit longer and I’m gonna wanna experiment a bit I’m sure. 
 

love the information on here, once I get things going, I’ll update

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6 hours ago, Firestorm102389 said:

. I think What I’m going to do is just make a modified sidearm set of burners to start

You could do that, but he has moved on, and now has a better burner design that is just as easy to build and hotter. You may want go to Larry's forge page, before you decide on what to build.

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Yeah I’d love to make one! I think I’m gonna experiment a little bit. So far I have stuff to build a traditional t burner, but right now I went with these, I figure it’s just another variation of the t burner but I can control the depth of the mig tip. Still gonna play around with the lengths of pipe, and I’m also going to be adding plates over the air ports for control. I wanted a cross that had (1) 3/4 port but couldn’t find one so I had to use a small threaded nipple and reducer.

i like the control I have to lower or raise the tip to find a sweet spot also.

 

It’s not consistently smooth all of the time, not sure why, but it is most of the time. Maybe I should swap out my .030 tip with the .023 And the .035 to see the difference. No wind in the garage, I didn’t run it for to long because of carbon monoxide, but I just wanted to see it work and tinker for a few minutes. 

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Are you going to at least pay a nod to the ratios that have been proven effective for a couple few hundred years? 

I understand and applaud folk who tinker with things, I'd have to be a jerk bucket not to, seeing as how may improvements to home built burners have been made in the last decade. Unfortunately the improvements have been made by folks who understood how they work. 

Frosty The Lucky.

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Yeah I gotta clean my shop up. I also just made a couple t burners like frostys, and I gotta say, I think I like them more than what I posted pictures of. They’re simple, and they work better than the ones I made initially, mainly because the tubes that hold the contact tip in my first ones has a little movement, and the t burners how frosty does them, the tip will stay in the center much easier. 
 

frosty, what ratios are you referring to? The sizes of the tubes and reducer bells and such? I tried looking up all that many different places, I think I had them right but I could be wrong. First ones I used a 3/4 pipe at 8” with a 1” bell reducer at the end and a 1” bell on the top with the cross fitting. 
 

the ones I just put together in my garage today I used 1” T reducer to 3/4” pipe to 1” bell reducer on the end. Am I supposed to use 1-1/4” reducer T to 3/4”?

 

as far as understanding how the burners work, I understand how a carburetor works and that’s based on the Venturi. I had a pneumatics class in college for understanding brake lines and caliper piston travel. Based on the carburetor, and the pneumatics class with sizes of tubes and how it effects the flow and force along with carb air fuel mixtures, I’m using the same principles as I believe they apply very similarily

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Yup, I'm the right Mikey :rolleyes:

Nice video; it doesn't show any major problems, but rather a little further work needed to complete your burner. Lets take it one step at a time, and you can record the flame improvement after each step.

(1) Widen each of those four air openings a little more; stop short of taking so much material away that your ribs (between the openings) become weak. This problem is one of the reasons that I changed the designs of all burner sizes to three air openings.

(2) Bevel the forward ends of all four air openings, so that the knife edge is on the outer surface. How steep a bevel? I like sixty degrees. You will be amazed how much that increases airflow into the burner.
 

(3) It didn't have a great effect before, but you will now find that keeping the end of the MIG tip somewhere between 1/4" and 3/8" back from even with the knife edges creates a sweet spot for fine tuning the burner.

(4) Now the amount of length between the forward edges of the air openings and the end of the mixing tube will matter a lot. Best overall length is nine times the inside diameter of the mixing tube. Longer and you soften the flame; losing some heat, but improving performance for open air brazing. Shorter and the flame gets a little too hard for general use. This fact can be used to manipulate flames in equipment to keep them from impinging on the work surfaces, as they grow conssiderably shorter.
 

(5) With these improvements you will find the thin forward edge of your present flame retention nozzle oxidizing away in about one month of home forge use. So, start making its replacement now. Your first design was fine; just do it again. So what about lengths? You need the outside diameter of the spacer ring, plus additional 1/8" for overhang; add that to whatever length you cut the spacer ring to. You should find that your flame goes from hard to soft in just that additional 1/8". A sliding flame retention nozzle is for coarse tuning. The gas tube sweet spot and and choke are for fine tuning. When you change gas pressure, you may want to change fine tuning. Nozzle position doesn't change once properly set for the flame you desire.

More questions?

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2 hours ago, Mikey98118 said:

Yup, I'm the right Mikey :rolleyes:

Nice video; it doesn't show any major problems, but rather a little further work needed to complete your burner. Lets take it one step at a time, and you can record the flame improvement after each step.

(1) Widen each of those four air openings a little more; stop short of taking so much material away that your ribs (between the openings) become weak. This problem is one of the reasons that I changed the designs of all burner sizes to three air openings.

(2) Bevel the forward ends of all four air openings, so that the knife edge is on the outer surface. How steep a bevel? I like sixty degrees. You will be amazed how much that increases airflow into the burner.
 

(3) It didn't have a great effect before, but you will now find that keeping the end of the MIG tip somewhere between 1/4" and 3/8" back from even with the knife edges creates a sweet spot for fine tuning the burner.

(4) Now the amount of length between the forward edges of the air openings and the end of the mixing tube will matter a lot. Best overall length is nine times the inside diameter of the mixing tube. Longer and you soften the flame; losing some heat, but improving performance for open air brazing. Shorter and the flame gets a little too hard for general use. This fact can be used to manipulate flames in equipment to keep them from impinging on the work surfaces, as they grow conssiderably shorter.
 

(5) With these improvements you will find the thin forward edge of your present flame retention nozzle oxidizing away in about one month of home forge use. So, start making its replacement now. Your first design was fine; just do it again. So what about lengths? You need the outside diameter of the spacer ring, plus additional 1/8" for overhang; add that to whatever length you cut the spacer ring to. You should find that your flame goes from hard to soft in just that additional 1/8". A sliding flame retention nozzle is for coarse tuning. The gas tube sweet spot and and choke are for fine tuning. When you change gas pressure, you may want to change fine tuning. Nozzle position doesn't change once properly set for the flame you desire.

More questions?

You wouldn’t have another video showing your updates by chance would you? Haha. 
 

so instead of 4 openings like your video, I should use 3 slightly larger openings with top and bottom knife edges filed from the outside instead of the lower ones filed inward?

 

As far as the contact tip, is that 1/4 or 3/8 from lower knife edges, or recessed in the top before the first upper knife edges?

9x 3/4 would be 6-3/4, and that’s not overall length but rather after the lower knife edges, correct? So the overall length of just the tube would be the 6-1/2 mixing tube length, plus what I need for the air openings and the threads on top for the cap. That just leads me to one important thing then. What are the dimensions of the 3 air inlets then? You had the 4 in the video, so if I’m going to go with your better improved one of 3 openings, how wide and long are you making them?

(guess I’m assuming you mean the lower knife edges when saying forward btw?)

 

im really glad you’re on here and I can learn from you what has worked, I want to thank you for everything in advance  I know I really appreciate it and I’m sure any other new novice blacksmiths, like myself, will appreciate it as well. I love building things and this is going to be a great project.

 

one other thing I couldn’t find anywhere, I was looking at this style vs the t-rex style, I noticed the big difference to my inexperience, is just they have a funnel before the mixing tube. Is there any reason they add that if yours works great?

 

 

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Mikey's answers: I was under the impression that it was your video?

If not, that is all to the good. You you can lay out your burner with three openings, instead of four. How to do that the easy way? employ a bolt from your local hardware store, and some electrical tape, with which to mach its shank to the inside of the mixing tube.  The hex head is perfect for lining up three equally spaced places for air openings. Next, use a short piece of aluminum or steel 3/4" angle as a straight edge for tubular surfaces, to lay out your linear lines for air openings. Use the choke to layout the cross lines, and to ensure that your air openings line up correctly with where your choke is located (if you have the sleeve running in its own slot).

I only mentioned beveling the forward edge of the air openings in the burner featured in that video, because the modified pipe fitting provides the proper shape for the rear openings. If you are planning to use a tube, with air openings cut into it, then the rear openings will also need to be beveled; but with the knife edge on the inner surface of the mixing tube.

You asked: "As far as the contact tip, is that 1/4 or 3/8 from lower knife edges, or recessed in the top before the first upper knife edges?" 

Let's restate our terms. Outer bevel edges are found on the forward ends of the air openings, and inner bevel edges are found one the rear ends of the air openings; just as pipe fittings are beveled that same way. The MIG tip, or any other gas orifice, is placed with its end between 1/4" and 3/8" away from (to the rear of) the forward knife knife edges. So why not continue the bevel into the threaded portion of the pipe? Because, you would have a mess to deal with if you ever decide to remove the reduce fitting in the future; this would be in return for very little gain in performance, because pipe threads are already very thin at their forward edges, and because the amount of air flow improvements are 80/20/80; that's 80% improvement at the forward ends of the openings, to 20% at the rear. However, the lip on the reducer fittings create major problems in air flow; in for a penny, in for a pound. It is only reasonable to perform a little added work to bevel the fitting as you get rid of that lip.

You stated: "9x 3/4 would be 6-3/4, and that’s not overall length but rather after the lower knife edges, correct? So the overall length of just the tube would be the 6-1/2 mixing tube length, plus what I need for the air openings and the threads on top for the cap"

You're half right. The overall length of the mixing portion of the burner is measured between the knife edge of the forward ends of the air slots to the end of the tube. But you're dead wrong about the measurement. The burner size is 3/4"; this is the nominal pipe size. You will find that the actual inside diameter is close to 7/8"; that will be over one-inch longer. Rather than measure the actual inside measurement of every pipe or tube used, I settled on 8" for the mixing portion on 3/4" burners.

You asked: "What are the dimensions of the 3 air inlets then? You had the 4 in the video, so if I’m going to go with your better improved one of 3 openings, how wide and long are you making them?"

Again, that isn't my video. Several people have built their own versions of Mikey burners, and posted videos; I never have. "You asked: "What are the dimensions of the 3 air inlets then? You had the 4 in the video, so if I’m going to go with your better improved one of 3 openings, how wide and long are you making them? "

The air openings are as wide as you can make them without seriously weakening the three ribs between them. The hex bolt can be revolved a little way after making the first three lines, so that you can easily see where you want the second three linear lines to best suit your purposes. As to air opening length, 2" should work out fine. However, if you think it is short, the openings can be lengthened. If you turn out wrong about the further length, it matters very little. So how do we know how long is perfect? When you open the choke completely, the burner flame should increase size and strength all the way. If there is some length at the end of its travel , which  doesn't change the flame, that portion of air openings wasn't needed. You're probably wondering why I chose long narrow openings in the original design, yes? I was "playing it safe." Thousands of people were going to end up following my burner directions, and after four years of people doing as they pleased, an then claiming "I built it just like you said" when they obviously didn't, I wanted to build in wide safety margins. Thousands of builds later I'm feeling LESS paranoid.
 

You asked: "one other thing I couldn’t find anywhere, I was looking at this style vs the t-rex style, I noticed the big difference to my inexperience, is just they have a funnel before the mixing tube. Is there any reason they add that if yours works great?"

Because the Hybrid burner is based on my early Mini-Mongo burner design. Rex corresponded with me for about six months while I was first writing Gas Burners for Forges, Furnaces, and Kilns. Then he decided I should not write a book about 'his' burners. He even got Ron Reil to take down the color drawing that I  had posted on his site, at his request!!!

Rex made one change in the design, which I heartily  approved; that was changing out my lines of air holes to slots; on like him, I immediately began researching why it improved performance. He one-upped my holes with slots. So, I one-upped his slots with beveled rectangular air intakes. There was such an improvement in performance that reducer fittings became an irrelevant nuisance.

I  want right on thinking designing and learning. Price hasn't  come up with a single improvement since I stopped corresponding with him, about eighteen years back. It looks like his business is finally done. "He who lasts last lasts best."

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I have not gotten the book, but I very well might at some point. 
 

I made 2 t burners for now, and figure I can play around with the others because these work quite well. I can always swap burners if I make a really nice one to change out. 
however, I did have to remake one of my t burners as the hole wasn’t completely straight. Ever so slightly crooked and didn’t perform as well as my other one. So I did that today and both work great, but I did have to use an 8” pipe nipple instead of 6” and a .030 instead of .035. Those changes is what gave me a nice clean blue/blueish white flame with very little orange. It performed well all the way from maybe 4 psi up to 15 maybe even 20, got a fair amount more orange on the outside of the flame after that. But all in all, I’d say they work well enough for me for now. I did the math on the propane tank I’ll be using to make the forge, and 2) 3/4” burners is what I’ll need. Figuring how much cubic inches after I added the ceramic blanket and the refractory 1/4” layer all around with 2 fire bricks at the bottom, I’m looking at probably 600 cubic inches interior. I’m havinga front door as well with a smaller opening on the door and I’ll be able to block off the rear and part of the front openings with fire brick if need be. 
 

the big door I’m putting on the front is more for future maintenance. It would be a lot easier to redo the lining and stuff with full access. Once I actually start going on it, I’ll start taking pictures and make a new thread with the build. 
 

im definitely a novice, but with what I’ve learned in college, here, my career, I feel pretty confident about this build. I think the only thing I don’t have in the plan is itc 100, but I saw something about a kiln wash I think it was A mix of sand and clay to put on last over everything else. 

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On 11/18/2020 at 1:26 PM, Firestorm102389 said:

frosty, what ratios are you referring to?

The same ratios I've posted here and other fora and email lists for years, the same ones Ron Reil and Mike used to design theirs. 

What's with all the bell reducers? ONE as a nozzle flare can be tuned for but it's only okay. 

The T burner directions are in the gas burner section under their own sticky.  Let me know if you don't understand the ratios.

If you want to get an idea of how a T works look up "jet ejector".

Please don't get the idea I'm upset nor willing to help you get it right. I tend to run out of sorts when I see my name attached to poorly understood burner like objects.

Frosty The Lucky. 

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All good frosty. I looked up some stuff on the t burner and on here. , the t burner I made only has a bell reducer on the flame portion. I used the 1”x1”x3/4 T connected to 8” pipe nipple and the bell reducer and .030 mig tip. I put 6”, 8”, and 10”  with the .035 and .030 contact tip and the best flame comes from .030 from 5 psi to 15. If I go above 15 I’d need the .035 I found at least for where I live that’s what I got running the best. I’m judging the flame as best I can based off when I used torches to cut steel with, but these are much bigger that a torch tip, but I know its running good. 

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I based how I tuned propane burners on my schooling and years of experience running oxy fuel torches. Home built air propane burners don't produce the same flame zones and it can throw you off tuning them like they do. 

What you're describing now isn't what you showed in the pic is it? I was referring to the bell reducer between the T and mixing tube. It's a serious performance reducer.

You're getting a "better" flame with smaller jets because the mixing tube is too long. It requires a higher velocity gas stream to overcome the excess friction of the long tube. Which means you're pushing the mix at a higher velocity so more flame is blowing through and out of the forge. The longer the fire stays IN the forge the more time it has to transfer energy to the forge walls.

Flame heating the forge walls which radiates IR to heat the work is how a "regenerative furnace" works. Direct heating of the work by the flame is a very small % of it's job.

Frosty The Lucky.

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