Prajna
Fixing things for the love of it
- Messages
- 512
- Location
- Castelo Branco, Portugal
So I naively ordered a bunch of galv box section to make a frame for a small building. A friend went to arrange it and organised delivery of 80x40x1.5mm galv box. This was before I took up welding, indeed it was what prompted me to do so. Then I found the forum and started reading all the threads about welding thin stuff, or rather not welding thin stuff if you can help it and if ya do then mig it or tig it.
I didn't have anything that size to practice on until a few days ago. Then a mate gave me some lengths and I set about seeing just how difficult it really is. The first day I blew holes all over the place and laid down some pretty snotty welds in the places I didn't burn through. But I did notice that some of the welds went ok. So this morning I had a brain wave: I could try capping the ends of the tube before joining them. And it worked.
I cut out a 80x40 cap from the same stuff and welded it on the end of the tube. All easy outside corner joints:
That went in nicely at 40A with 2mm 6013s. Then a little cleanup with a flap disk:
Then I could T joint that to another bit of box treated the same way with 2.5mm 6013s at 50A round the outside and 60A along the fillet without blowing holes everywhere.
1.5mm doesn't mind a hot pass across the middle, it's edges that are delicate. Two equal edges will weld nicely at low amps so long as there is a good fit up. Once capped an edge will stand as much heat as the middle of a sheet.
What began as a seemingly insurmountable problem became achievable with a little lateral thinking.
Now I can concentrate on practicing these jounts to make em look really tidy. Will post a pic of the completed T joint when I have a tidy one.
I didn't have anything that size to practice on until a few days ago. Then a mate gave me some lengths and I set about seeing just how difficult it really is. The first day I blew holes all over the place and laid down some pretty snotty welds in the places I didn't burn through. But I did notice that some of the welds went ok. So this morning I had a brain wave: I could try capping the ends of the tube before joining them. And it worked.
I cut out a 80x40 cap from the same stuff and welded it on the end of the tube. All easy outside corner joints:
That went in nicely at 40A with 2mm 6013s. Then a little cleanup with a flap disk:
Then I could T joint that to another bit of box treated the same way with 2.5mm 6013s at 50A round the outside and 60A along the fillet without blowing holes everywhere.
1.5mm doesn't mind a hot pass across the middle, it's edges that are delicate. Two equal edges will weld nicely at low amps so long as there is a good fit up. Once capped an edge will stand as much heat as the middle of a sheet.
What began as a seemingly insurmountable problem became achievable with a little lateral thinking.
Now I can concentrate on practicing these jounts to make em look really tidy. Will post a pic of the completed T joint when I have a tidy one.