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View Full Version : BS MIG welds, how to improve?



*chris*
10-17-2008, 11:54 AM
I am welding up some 12 gauge sheet metal and my welds look like crap. I am using a Weldpak 175 with 0.0025" wire, C25 gas and the forehand (push?) technique. As you can see there is no consistency. The reason why the beads looks like crap is I have to move so fast otherwise the wire punches through. My glove doesn't move smoothly therefore the bead is not smooth. What do I do?

Can I simply turn down the wire feed speed until it deposits at a rate I can handle? As far as I remember from my single welding class, I can't turn down the current as it is needed for full penetration.

Thanks.

Chris

http://woodwurker.com/webimages/20080928dust01.JPG

TSOR
10-17-2008, 12:20 PM
Turn the machine down. Slow down. Drag don't push. Use both hands to steady the torch.

SundownIII
10-17-2008, 01:11 PM
Chris,

Corner joints, like those you're making, are generally done at 10-15% less voltage and wirespeed (Amps) than those done in the flat position.

That said, dial your machine back slightly, and slow down the movement of the gun.

Push is the best technique for this type of weld. Dragging the gun will give more penetration, which is something you don't need in this type of corner joint.

Oldiron2
10-17-2008, 02:12 PM
I would suggest finding some clean scrap material of the same thickness to practice on so you can experiment with settings and procedures without ruining your project. Get good before you start your project; it's easier to do it right first time than have to fix it. Even if you've done it well a time or two before, it doesn't hurt to brush up when you're rusty at anything.

*chris*
10-17-2008, 03:52 PM
Alright, since I have a tapped machine, is it worth just dropping down a tap? I know I should push as I want a flatter bead. I will also cut back on the wirespeed a bit.

Chris


Chris,

Corner joints, like those you're making, are generally done at 10-15% less voltage and wirespeed (Amps) than those done in the flat position.

That said, dial your machine back slightly, and slow down the movement of the gun.

Push is the best technique for this type of weld. Dragging the gun will give more penetration, which is something you don't need in this type of corner joint.

MoonRise
10-17-2008, 03:57 PM
Yes, you can turn down the wirespeed. The 'recommended' settings are just that, a recommendation. You can (and often have to) adjust a bit depending on joint fit-up and layout and user preferences. So turn down the wire speed (which is the amps) slightly and then you slow down on your travel speed.

And your wire is 0.025 inch diameter wire. You listed an extra zero in there, making for a wire that would be about as thick as a piece of standard paper or a typical human hair.

And for MIG (GMAW) you -usually- do want to 'push' the wire (forehand) to make sure that the pool of shielding gas is actually shielding the weld. For FCAW, you 'pull' the wire (ie, if there's slag, then drag).

OK, you posted just before I posted. You do not need to drop down the voltage tap just because you slightly lower the wire speed. You lower the voltage if it is too high for a given wire speed, as evidenced by too much spatter or other signs of the voltage being too high. If you turn down the voltage too low, then the wire will 'stub' into the work and push the gun back as you are trying to weld.

Dan
10-17-2008, 04:16 PM
I've only ran Lincoln's variable voltage units in the 175/180 amp class, so I'm not familiar with the output ranges on the Lincoln's 175 amp tapped V units. However, with my Hobart Handler 187 or a Hobart Handler 210, I'd definitely drop down a V tap on an outside corner joint, over what I'd have the machine set for a T or lap joint. This is based on running in a flat or horizontal position.

It definitely won't hurt to try a tap lower on some scrap.

*chris*
10-17-2008, 05:24 PM
I think this is the key of my issue, I didn't realize/experience that you need less power for outside corner joints. With thicker material this doesn't seem to be as noticable meaning thicker stock is more forgiving.

I always perfrom a quick butt joint test which comes out fine.

Chris


I've only ran Lincoln's variable voltage units in the 175/180 amp class, so I'm not familiar with the output ranges on the Lincoln's 175 amp tapped V units. However, with my Hobart Handler 187 or a Hobart Handler 210, I'd definitely drop down a V tap on an outside corner joint, over what I'd have the machine set for a T or lap joint. This is based on running in a flat or horizontal position.

It definitely won't hurt to try a tap lower on some scrap.