Train wreck

[Daniel Brannan]

Hi

Once again I’m struggling with TIG on aluminium. I’m copying a fuel tank by hammering a sheet of 1.5mm 1050 aluminium round a dolly (old tank) and where the metal creases, chopping sections out. This went fairly well and I managed to tig up the seams where I cut metal out however when I checked behind the welds they were far from perfect as i couldn’t get the fit up great so there were holes. So I thought I’d do a pass from behind. From this point on, the wheels have come off. Black soot, edges dropping away from you, contamination and it just holes. So I purchased some of that king weld backing tape to protect and support it from behind. What a waste of money - 50 quid and the fibre glass strip in the middle just melts and contaminates the weld.

Here are some pictures for your amusement including one of the melted tape. What a disaster. So now I don’t really know how to proceed. I am unable to finish the job currently. Any suggestions welcome

 

[tigdlo]

So I purchased some of that king weld backing tape to protect and support it from behind. What a waste of money

Aluminium forms an oxide layer on the back side protecting itself, as long as the backside is clean it's unlikely that's where the contamination is from.

Run a 100mm long bead on flat sheet the same thickness as your tank whith an airgap behind as there would be when welding the tank, post photos of both sides without cleaning it.

 

[Daniel Brannan]

Thanks. So this was a piece of the same alloy and thickness, same filler, same gas settings. Pictures below. 1 was without even brushing the metal before laying the bead, just a quick wipe. 2 was a bit more of a thorough clean. No brushing or cleaning afterwards on either.

Might probably also be worth mentioning - when I was welding on the tank the arc was wandering all over the place. Like quite dramatically. This didn’t happen on the test piece in these pictures

 

[Rising.Frequency]

Welding 1.5mm 1050 as a beginner is gonna be real tough.

It’s always going to be easier running a bead on solid sheet rather than a joint.

Have you got any pics of your fit ups before welding?

When you say you’re chopping sections out, what with?