novice tig welder- maxstar 150 stl

[traveleasy]

I am practicing on thin wall 0.035 4130 tubing with about 30 amps. I don't know the proper techniques for tigging a notched joint that dues not have a perfect fitup. When here is a gap betwen the two parts, what is the proper technique?

Bob

[arc]

fill her up

take the filler metal and position it to one side that u are starting on and start the arc. then make your way across the gap to the other side the filler metal will follow the heat. then just moving the filler metal and the torch across the gap back and forth blending it into the edges just keep a eye on you heat input and when you got to stop make sure you tail out so you do not get crater cracks. if you have any more questions or dont know what i mean feel free to ask.one more question how big is the gap!? that is some thin wall tubing

[Tex]

4130

What are you welding? There's a book by EAA called aircraft welding that will give you TONS of ideas on fitting up tubing. Also (this is very important) you need to use backing gas. This consists of a Y adapter from your argon bottle with one of the hoses going to the inside of your tubing/pipe. It's not high-tech but it will improve the quality of your weld. Lastly...there was an article in Welding Journal a couple of months ago about welding 4130 chromoly tubing. If you have any specific questions I'd be glad to help.

[arc]

if you are going to use a back purge and the material is that thin, keep the pressure down and wrap a cloth around the end of the hose to act like a diffuser
this is very important to do so you get a good back purge and too keep the pressure down so you dont push the tubing out of shape when welding.