I know everyone in here are baller TIG welders but I figured I'd ask.

I passed my 2G bend test the other day so now im onto 3G. By the time I get to the last 1-2 inches of my 7" root, the weld just wants to fall out, obviously from overheating. I am trying to work as quick as possible as my instructor suggested, I only clean off the crater and continue my root right away, but it doesnt matter. I can quench my practice peices but obviously not my test piece which I wouldnt want to do anyways, I was thinking just run the first half and let it cool, then finish it?

its 3/8 plate with a backing strip, 1/8" 7018 I think im at around 115amps I honestly havent touched my dial since I began groove welds. Maybe im running too hot?

 

I can't tell you where your heat should be at without welding it myself but if I were to do what you are describing I would probably weld the first 3.5 inches and wait a sec for it to cool down then finish the other half. That way after you have waited for a bit when you start the second half the metal well still be warm enough to where you aren't having to do a cold start but still cool enough to where it won't fall through at the end.

 

yea I think I will try that. I dont think theres any way to do it all at once on such small plates. thanks

 

I run about 90 amps with 1/8 for a 3g pass. Also, when it gets near the end of the pass, you can go a bit quicker and it shouldnt "fall out". Its not always overheating, it can be from staying in the same position too long.

Do you use temp sticks? Thats the best way to tell where youre at heat wise.

 

I am going as fast as I can without leaving the edges underfilled.

if by temp sticks you mean like a thermometer or something, we have one but we dont really use it unless its cold out and we need to get a test piece to proper temp, I suppose I could use it for interpass temps.

 

When I tested out in that position I had the amps set to 130 on the testers advice.
All that matters is penetration and deposition, both of which are controlled by amperage.
If 115 is like 115 on most machines, it's not too hot. The two key factors are arc length and inclination. The ar has to be very tight, and you should have 5-10 degrees backhand inclination, or you can be 90 to the plate.
The key at the top is keeping that very short arc.

 

thats about what im doing, a very slight upward angle basically 90*. Im keeping it close but I can just see the penetration "hole" and the metal just falls out of it.

 

update: I think I was too hot because I turned the heat down and I made some really nice roots today with no overheating problems.

 

Yep, too much heat and it will just drip out. If it gets to building a "nipple" as I call it, turn the heat up a bit.