I have been in the packaged gas and welding supply industry for 31 years. I am the Regional Training Director for Airgas National Welders at this time. I do not pretend to know all things about welding but I have been around the block a few times when in comes to arcs and sparks.
I hate to be the bearer of bad news but in this area, just like motorcycles, you get what you pay for.
Yes, Bargain Basement places have cheaper machines but in the long run, there is a price to pay. Go to Northern Tool or Harbor Frt. and ask them about thr heat effected zones in the welding process.
Metalurgy is serious business.
When you have hardened alloys, (like some frames in order to gain strength without them weighing a ton) the very act of putting a plasma arc to the metal destroys the temper and thus creates a very dangerous situation. I have seen welds that are cosmetically beautiful that will fail the very first time they are stressed, bent, pulled etc. All welds are not the same and not everyone who can strike an arc is a welder, I don't care how nice the welds look. (Have your welds been inspected and tested?)
Airgas has over 1100 retail locations across the US. Please find one, stop by and ask to speak to one of the account managers. Tell him that the one of the training directors for the company sent you in and you need some information about welding different grades of steel, stainless, aluminum etc. They will provide this for you free of charge. They will also be glad to show you safety videos (Welding can create some nasty gases if you have not found this out yet!) Please make sure you have the proper safety gear when welding. If you are using Oxy. Acet. Ask to see some safety information about that as well. You can also find out a great deal of information from the website - Airgas.com
If you have welded (Mig or Tig) on your frame, handlebars, or any part that takes pressure of stress - If you are not a certified welder - Please have someone that is qualified check the welds. You do not want to find out that the weld has cracked one night when you (or someone else) is cruising down the highway. Later Bud