I wanted a burner that could run well at very low pressure, but still crank it out.
Design Goals:
- Easy to build
Cheap
Minimal parts
Easy to modify for different uses
Compact and light
I also decided to base it around a mig tip, so that I can easily swap out the jets for different uses. Using one that has a .037 hole right now. It's the standard one that comes on cheapy welders and handles .030 wire. I happened to have 2 of them lying around.
I used a more narrow burner tube than most burners I have seen. I did this because I deduced that the volume of the jet compared to the volume of the tube should determine the relative velocity of the intake air. So I figured the closer they are in size, the more acceleration the intake flow would have. I believe this will allow the burner to function in a much wider range of PSI, but not handle abrupt PSI changes. Good trade off in my book!
So basically, I grabbed a mig tip and tried to use as few parts as possible to hook it to a gas line. Jammed that in the end of tube. Cut my slots and tried it out. It took a bit of tweaking and I played with a few different nozzle flange designs. Here is a shot of the flame I was getting off the first Mako burner. At this point, there were a few little problems. In some PSI ranges there was popping and some whistling. I ran it in my new mini forge with no flange and that worked out ok. Some popping, but all in all, I had a great flame at around 7 psi and it ran steady for a few hours of smithing
Running it that long let me observe it acutely. Seeing when it popped that flame would sometimes come out of the front vent holes and at high pressures the flame would walk off the end some.
It was time for Mako 2.0: Here it is running at 4 PSI I could tell you, I was quite pleased at this point. I wanted to be able to run at lower pressures, but I never expected to have a flame like that under 5 PSI when most venturi burners I have seen run at 15 PSI and up. With my Oliver Upwind, I could run it at 10 ok, but it liked it higher and I NEVER got a flame like this out of it at any pressure. It runs at a wide range of pressures, I'll do more accurate testing and documentation soon, but suffice it to say, from VERY low PSI to more than enough PSI
The wires you see on the nozzle flange are multi-purpose, they hold the nozzle in place and centered by standing off the burner tube, but they also provide points that are as wide as the flare opening so that it can self support and self center in a tuyere of the proper diameter.
It basically SNAPS into my mini forge and mini furnace tuyeres
I could think of no other improvement or tweak, so I decided to put it to the test...
Now, I don't understand this and I KNOW it is hard to believe.... but.... guys.... I was running this burner at maybe... 1.5 or 2 PSI in the following picture. It was such low pressure that my gauge was barely off the peg and it's not designed to be accurate to fractions of PSI, so... It's VERY low... WELL under 3 psi, probably under 2 PSI... HONESTLY! That is a railroad spike glowing orange hot in NO TIME! Me and my buddy smithed out of this thing for hours at below 2 PSI!!! HOW IS THIS POSSIBLE??? Don't ask me... I don't know the math of PSI to BTU, but I know that this burner at 2 PSI is more than enough heat to QUICKLY heat even thick steel to glowing red hot, through and through.
The burner behaved PERFECTLY and was unimaginably quiet and hot. No heat is transferred up the burner tube. You can touch the entire burner tube even after hours of running it like you see it in that mini-forge. Not the flange, of course, but the main tube stays perfectly cool.
I believe I met all of my design goals and exceeded most of them. Here is another shot of the completed burner. I call it a "Mako" burner because it has 5 sets of gills. It's also sleek and formidable and not fully understood