Sunday, June 8, 2014

Forge update - gas adaption

When I woke up this morning I didn't know I was going to be converting my coal forge to gas. While on a family trip to Home Depot, I snatched my son up and we split away from my wife and daughter. I did my typical run around to see if anything good was on sale, look at esoteric stuff, and maybe find inspiration for a new weekend garage project.

I was never enthusiastic about playing with flammable gasses, but another project (you'll see in a future post) had me learning how to use Acetylene and Oxygen cutting tools. Acetylene and Oxygen is a potent mix fraught with all kinds of danger. After learning about and circumventing all of the ways to kill myself with it, I'm simply amazed more people don't get hurt using it. By comparison propane seems tame, so when I ran across some refractory cement at Home Depot it didn't seem like too much of a bad idea to build that gas powered forge I've been planning for a few years. Earlier in the week Harbor Freight had a sale on propane torches and I picked one up for next to nothing.

This propane forge is nothing more than a fire-proof container with a hole in the side where you can drive in fire. The pressure of the propane leaving the nozzle sucks air in via the Venturi effect. Here's a cool video by Mathias Wandell about the Venturi effect. Some forges have active air (like a supercharger) driving air by fan, but it's not really necessary. Especially for a back yard forge. The container keeps the heat in allowing you to approach the 3000 or so degree burning temp of propane in air over a wider area.

I created the fire-proof container by cutting/bending some steel mesh to fit inside of a paint can and packing the mesh with the refractory cement. I just used a pair of rubber gloves to smash it all in there and smooth it. Here's a picture of the process.
I cut a hole in the side and then very carefully welded in a piece of square pipe large enough to hold the torch tip. Another set of pictures showing how that works:

The front view of the forge after the first burn:

I scavanged a piece of 1/2" angle iron from a bed frame were throwing out. I cut that up and welded it together to create the stand which the paint can sits on. I sized it so that it fits on top of my coal forge, effectively using my brake disc coal forge as a heavy stable stand. Here's a picture of the whole setup sans propane. I took these pictures after I had already put away the propane for the day.

Before this forge will be truly usable, I'll have to figure out how to narrow the front opening. I'll probably use fire bricks, but not sure yet. I'm out of time this weekend.