Why TIG?

A short while ago, someone on a mailing list I frequent asked "Why TIG?". In context, he was asking why TIG is preferred over other forms of welding, such as MIG. The above picture illustrates one of the reasons. Keep in mind, I'm basically a rank amateur when it comes to welding...

Frankenrocket

I've welded the torch igniter onto my current chamber. As you can see, its rather disproportionate ... a good example of "minimum gauge" issues. The igniter is built around the smallest reasonable orifice sizes (0.014") for the fuel, and the various design constraints lead to what you see here. It was dubbed the "Frankenrocket" by my brother ... and as such it will be known.

I hope to be able to test it this weekend, but in the meantime, I've been working on the next iteration of this engine. I'd like to get away from the igniter for obvious reasons and get back to direct spark. So with some cleverness, a 8mm thread plug, and a step up in my fab skills, I think I've come up with a very compact design that moves the spark plug back onto the injector face and still yields a much smaller engine. I've made a fair start, but I burned out some MOSFETs on the lathe, so I'm stuck waiting for Mr. Postman...