Welder settings based on joint preparation

[jgor]

Ok, this popped into my head today and I can't wait until next week to ask my instructor. I've searched all my books and can't find an answer.

Say for example that you have a butt joint - 1/4" steel, prepared with a groove, 1/8" root face. Would you set your welder up as if you were welding 1/4" material or 1/8" material and run multiple passes? Maybe this isn't the best thickness to illustrate what I'm trying to say but hopefully you'll understand what I'm getting at.

I've gone over this so many times in my head I'm starting to confuse myself as I can see pros and cons to both.

Thanks,

John

p.s. Apologies to the two people who read my question before I came back and edited it for clarification.

[Mike Sherman]

Your reference must be to short circuit mig. The only time you may have a problem is on the root pass. After that you need to set for the thickness of the steel. One big reason is the heat input as it relates to fusion or in the case of short arc mig, lack of fusion. To summarize: Root pass may require lower setting, all other passes set for steel thickness.

[jgor]

Mike,

Thank you for the clarification. I'm playing with MIG (GMAW/FCAW) and SMAW at this point so my question really relates to both processes. With your explaination it now makes sense to me as to what I'm trying to do when I weld. Too much heat on the root and you blow through, not enough on subsequent passes and you don't get complete fusion.

Thanks again,

John

If I ever win the lottery I'm going to travel around the country and pay some of you to let me watch you weld for a week!

[Mike Sherman]

You are only about 8 hours from my shop. E-mail first and come out any time you want. I am 20 minutes East of Erie Pa. Bring your helmet and stand out in the shop and watch the men work. Heck, I'll even let you weld a little bit. I figure 6 hours of free labor ought be fair payment for letting you watch for 2 hours. Just kidding.

[jgor]

Hah, thanks for the offer, I may take you up on it sometime. You do drive a hard bargain though with that 6:2 ratio!

John