gmaw vertical

[wooganwelder]

Hey guys im new here. So at school im welding vertical 35 wire with 75 25 gas. The steel is a little less than 1/4 inch thick angle line. Im making 3 passes. The first pass always comes out perfect. The main body of the second and third are smooth and tight. The problem I am having is on the outer edges of the weld. I always have some minor under cut on the outside. Now I am pausing shortly before continuing the pattern. Any advice on how to rid myself of this.

 

[Hitch]

Vertical up, or down?

 

[wooganwelder]

first pass is welded top to bottom with a very slight weave patter. Last two passed are bottom to top with same said weave pattern

 

[Hitch]

Could you turn the amps down just a few?
Failing that, dont point the torch up at such an angle. Only a few degrees could make the difference.


What is it you are welding up?
Is it to a specified procedure?
I think id be inclined to do the first pass up, than a cap downwards to tidy it up.

 

[Justme]

Thought that it was up for the root weld then down to finish it off?

Justme

 

[HughF]

Same here, I'd shoot the root in vert up, then put the caps on vert down. Could your undercut also be due to heavy millscale? Try and make sure the plate is clean

Are you grinding back after your root or is the cap going straight on?

Might be worth asking over on the ukwelder.com forum as well

Hugh

 

[wooganwelder]

My professor, Dwight Bower has 30 plus years experience so I trust his instruction in running the root pass top to bottom,,,,,,,He is so busy though that I feel bad for botherin him about such a minor thing. Im a bit of a perfectionist though so any deficiency bugs me,,,,,,i think my heat may be a bit too high

 

[Drains]

Is this an external 90 degree weld you are doing?
If so, i'd agree with the downward root pass because you would want to minimise penetration. For the upward passes, definitely turn down the amps, and/or don't weave much because you will be applying too much heat, hence the undercutting.

But really, if you have a tutor with 30 years experience, who is being paid to teach you.... well, make him earn his living!

Let us know what he says!

Si

 

[Marky Mark]

A root weld can be made either up or down, when trying vertical up you will need to reduce amps to compensate, dont forget you've just made a pass once, so you may need to reduce amps further if the piece hasn't had time to cool!