Burner Background - The Mikey Burner

About 18 months ago, I got interested in pattern making and melting metal to make castings.  I subsequently visited an iron foundry, read up on backyard metal casting through the Internet, and bought a number of books on the subject ranging all the way from pattern making, green sand molds, to making your own foundry and burners.  In March and August of 2010, I visited Alumalloy Castings in Scarborough, Ont and spent a few mornings watching them make castings from start-to-finish.  During this period of time, I made some patterns, acquired some green sand, made some flasks, got some sodium silicate and made some sand cores with CO2.

One of the books I got was titled "Gas Burners for Forges, Furnaces & Kilns" by Michael Porter.  Michael gave clear step-by-step instructions on how to build a naturally-aspirated (no blower) propane-fueled burner.  Manufactured from readily-available pipe fittings, the burner can melt aluminum, brass, and other metals.  The burner works so well that the backyard casting hobby has dubbed it the "Mikey Burner".  Here's a diagram of what I hope my assembled burner will look like.

A few weeks back, Joemac posted a video of his Mikey Burner on YouTube.  This inspired me to put my posterior in gear and try my hand at building my own 3/4" "Mikey Burner" using Michael's designs for the 1/2" burner.  I'm also incorporating a few modifications to the parts list to simplify fabrication of the burner using a bit of my limited knowledge of MIG welder parts.  

The main features that I like about the Mikey Burner (in addition to its simplicity and ease of fabrication) is that it is "naturally aspirated" - ie it doesn't require a separate blower and motor.  It makes use of the "venturi effect" whereby a large volume of air is sucked into the blower by the heat of the flame.  This volume of air (and hence the flame) can be controlled through a very simple choke sleeve that slides along the body of the burner.   

In addition to the flame being controlled by the choke sleeve, it can also be controlled by the "accelerator" - the part which introduces propane gas at 5-15 psi into the larger burner body.  

The propane fuel, which is at a higher pressure than the surrounding air, causes the air to be sucked into the burner tube where the propane gas is mixed with atmospheric air.  The ratio of fuel-to-air can be controlled by sliding the choke tube across the slots, or by sliding the accelerator in-or-out of the burner body through the bell reducer.  The air and propane gas are mixed and ignited at the far end of the burner tube.  The flame creates more pressure, thus drawing in more air until the end of the burner starts to roar like a jet engine.  Because of this high mixture of propane to air, high temperatures can be produced by the burner - sufficiently high to melt aluminum, bronze, and brass.

To give you an idea of how the parts go together, Joemac from the Casting Hobby discussion forum has put together a nice video of his modified Mikey Burner.


Here's how his 3/4" Mikey Burner works.
http://www.youtube.com/user/Joemac404#p/a/u/1/O2x_gFkicgA
Love that flame, eh!?