Welding Tips and Tricks

I am welding with an old Miller 330 A-BP. I'm having a hard time welding anodized marine tube. I find that I must remove all of the anodizing with abrasives before I can make a decent weld. This is very time consuming and tends to leave scratched areas around the welds. Would higher frequency (200 hrz) resolve this issue? Can the 330 A-BP be upgraded to allow welding thru the anodizing?

Hey mate. Welcome aboard. If you search Tamjeff on this page, you will find a absolute master of the art you are talking about. Even uses pretty much the same machine as you.

from what I understand, anodizing is basically a VERY thick oxide layer, therefore I doubt higher frequency would solve it. If anything, I would think a greater percentage of EP would assist in this but I've never attempted tig welding on anodized parts.

We had a job come in last year that required aluminum MIG welding support brackets on anodized extrusions. We found that the only successful way was to remove the anodizing by grinding, then the welds were all easy to do. We used an EWM Phoenix MIG welder, which is setup and excellent for aluminum work, but we couldn't get as good a result unless we removed the anodizing first.

TamJeff is the master though. He'll chip in hopefully.

Best
Trevor

If he doesn't, the basic idea is called bump welding. You set the welder hot and go on off on off on off. That way you have it hot enough to get through the coating, but the overall heat is reduced because of the stop start. A torch switch is really good for this.

iflyboth,
Your foot pedal (if you have one) should have a remote contact switch in it, and if you set your amperage control to panel and the contactor to remote, the pedal acts just like a torch switch. Then set the amps to 200 or somewhere north of there depending on how thick the base metal is. Hit the pedal and it should go instantly to 200 amps and form a puddle (couple seconds), add filler rod to the leading edge, remove, let off pedal, advance. Rinse, lather, repeat.

This process is a lot easier with an inverter where you can control the pulse, balance, and freq. but it's not impossible with an old school transformer. By the way the high freq. doesn't have anything to do with busting up the oxide layer, just keeps the arc alive through the polarity changes.

Len

Tried the bump on/off, seems to work, but I'm worried that it may not be too kind to the old machine.

Thanks for the info, I'll give the bump another try, and perhaps add a thumb switch too.

iflyboth,
If you can kill an old Miller A-BP then you'll be the first one. They're older than most of the membership here and harder to kill than stinkbugs, so I wouldn't worry.

Len

Once again, thank you for the info. I'm looking forward to trying it out.

Braehill wrote:iflyboth,
If you can kill an old Miller A-BP then you'll be the first one. They're older than most of the membership here and harder to kill than stinkbugs, so I wouldn't worry.

Len

This ^
You won't kill an ABP . Simple as that...