Well to be honest these are not my first results but the first ones that I was not too ashamed to publish.
Here's the welder and the thermalite and slab of steel I've been using as a mini welding table. You can see my new vent in the background. The disposable gas is a bit expensive but I've not yet sourced a North London supplier of Argon in larger bottles who does not require rental.
I started on some 3mm mild steel , which I cleaned up using a angle grinder and a flap disk. First experimenting with getting a puddle and practicing adding the filler rod (left) and then tacking and various pieces, one of the later results (right). I've still to do a strength test on these, my previous attempt just snapped right in half with a simple tap of the hammer. At this thickness I found 80-85A seemed to work about right, I expect as I get quicker I'll need to turn up the settings.
After three or four goes on 3mm steel I though I'd try some 1mm. I set the current down to 45A and successfully joined the sheet. You'll see I've a bit of a melt through at the edges but that should go with practice, the trick is not to stop when you get to the end.
Finally I gave a go with a T joint, I just tacked the re-bar either side to a small offcut of square steel bar.
LILLABO railway blackboard
4 hours ago