On 30/01/2021 16:32, Dave Plowman (News) wrote:
In article ,
Paul Benton wrote:
On Sat, 30 Jan 2021 11:34:53 +0000 (GMT), "Dave Plowman (News)"
wrote:

Looks like you could grind the welds down a bit more. Do they seem to have
penetrated both bits of steel? Looks don't much matter, but I'd need to be
sure the weld is strong. Covering it up with gobs of underseal is going to
make the tester look far more closely. And rightly so.

That's the main issue with MIG: you can't really tell! The truth is I
just don't know. I've jacked it up and belted it with a club hammer
and it ain't goin' nowhere. HOWEVER, whether it would survive intact
after a smash is another matter altogether. A complete unknown.

I'd try belting a few random globs of weld with a hammer and punch. If
they stay in place, they'll have penetrated.

I'm an expert at really bad welding. Despite practising and even modifying
my MIG to give a better slow speed wire feed, I've never mastered welding
thin stuff.

What type of wire do you use, and what was the shielding gas?

Cleanliness is key. It's tricky to get the feed right at low currents
and any contamination of surfaces will create vapour that destroys the
shielding gas properties.

I found gasless wire might be good outside but gives a pretty poor result.