[snowman]

Working on a project that requires welding 18, 20, and 22 Ga. sheet metal ductwork. Had the mig set up with .030 wire, 18v, 150 wfs. It's ductwork so there are lots of outside corners. Any suggestions/tips? Not used to working with such thin materials. Any help would be much appreciated!

[GarryH]

Far from an expert, but the manual for the 210MP lists the following starting points

18g 90/15.5
20g 80/15
22g 70/15

for ER70S-6 for C25
and
18g 90/18
20 80/17
22 N/A

for C100

hope that helps and I am sure much more knowledgeable people will chime in.

[Bill Beauregard]

I haven't done it in a while. By my way of thinking, you're on the thin edge of the capability of a MIG. I'd TIG, but if all you got is MIG, Bend a double 90 at the joint. I'd put a copper bar inside and weld on the outside. I'm guessing you're talking hot rolled steel.

[hardhatdiver]

.030" will work but .024" will make things go a little more easily. Fit up corner to corner and tack every two to three inches. Run your beads horizontal or run them down hill. I go horizontal and back step them.

[angus]

try an .023 wire. for 22 ga there is nothing faster than a Pittsburgh connection.

if you have the right brake you should be bending it so that you have one seam.

I would consider turning a 1/2 - 3/4 bend to bring up to the flat edge.

you don't mention material but at those thicknesses I would guess this is a low pressure system and is probably

galvanized (zinc) material; the heavier sections could be stick welder with 6011.

[Superiorwelding]

One thought and recommendation is to run your outside corners vertical down. You will achieve a full pen weld when set correctly without the fear of burning through.

Another option is to run pulse if you have that capability.
-Jonathan

[snowman]

Thanks everyone! All great suggestions that I can try. I usually only weld pipe and thick gauge steel but venturing into different jobs. Wish me luck.

[snowman]

Having lots of luck with .023 wire on the mig 15 v and 200 wfs with 18 and 22 gauge as long as I am careful of the heat and move around a bit. Also tried 1/16 6013 DCEN and that worked well to. Thanks everyone!