Practicing for welding round tube with 1.5mm wall.

[Dougal Thompson]

I'm new to Mig having used stick on and off over the years but for thicker materials. I now have a second hand Kemppi Minarc 180 with which I've spent some time on 3mm getting accustomed to Mig.
I've now turned my attention to 1.5mm flat plate hoping that practice on this will pave the way to round tube which I'm expecting to be somewhat tricky. The Minarc's automatic thickness settings seemed spot on for beads and lap joints, but I've had to reduce wire speed and volts a fair bit for a butt joint. Here's a pic of the current effort. Direction was right to left with a straight push, torch a little off vertical in both directions and a short stick out, .8mm wire, 2.7m/min, 16.7v.

I'm a bit lumpy at the start, ok I think in the middle, then lose my way a bit after welding over the tack which was perhaps a little large.

Here's the reverse for penetration which seems ok, with the same provisos as above. (I'm not worrying about distortion on these practice pieces, more about getting the correct size and penetration bead).
Should the bead be a bit flatter? If so what changes are likely to achieve that? I'll keep practising at getting a more even run, are there other excercises that would help towards welding tube?
Thanks for any comments and criticism.
Dougal.

 

[Dougal Thompson]

Oops! That's actually 1.00mm sheet. And the settings arrived at are spot on the auto ones. Now there's a surprise. So need to get some 1.5 and start over.....

 

[Country Joe]

Hey, Mr T - a belated welcome to the forum!

You’re onto a winner with the welder, those Kemppi MinArcMigs are very nice to use!
You never seem to have to stray very far from the auto settings, if at all.
And it’s good to see some properly cleaned up steel, too!

The overall weld is reasonably slim, but tidy - as if the travel speed could come down ever so slightly, or even slightly more wire-feed - but you’re definitely not dumping isolated blobs of steel along the weld-line, as would happen if you were screaming along far too fast - at double speed, or the like!

The second shot (the reverse side?) has so much penetration it actually resembles a “top-side” weld, too.
In fact the reverse looks better than a lot of the “critique-seeking” posted on here, showing the top-sides.

I’d say it’s definitely a full-penetration weld, you have there!

I’m assuming you’re wanting to weld a piece of tubing to a piece of flat stock?
Generally the trickiest part is maintaining your torch angle, arc-length & speed of travel, as you work around the circular tube-end.

This can make it tricky to achieve in a single pass, as you’ll need to move yourself around to maintain any view of the far side of the weld - unless, of course, you’re using a turn-table to get it done!

I’d probably weld as far around the work-piece as I could manage comfortably, as when you try to lean/reach too far, the arc-length (plus all those other aspects listed above) etc will vary, and the weld tends to go awry.

If one piece of stock (the flat or the tubing) is much thinner, it’s best to bias most of the arc on the thicker piece, to avoid burning through the less sturdy piece.

I’m well behind, so I’ve got to go!

And again “Welcome to the Forum!”

All the Best,
CJ

 

[Dougal Thompson]

Thanks for the welcome and reply.
The tube will be saddle welds and butt welds plus some brackets and threaded inserts.
I'm going to pick up some 1.5 plate for a practice plus I've got a few meters of tube to move onto.
I'll probably be back with lots of questions once I get into the practice pieces of tube.
Dougal.