Today, after improving my mold for making my aluminium "welds" I had a go at joining two pieces of 2" aluminium bar. I was hampered by being unable to locate my other G clamp and had to clamp one piece of aluminium down using a brick - which wasn't ideal as I couldn't get it close enough.
The welding wasn't actually "welding" I just melted some Harbor Freight "Aluweld" into the gap between the two pieces of aluminium. I'd cut the pieces and then chamfered one side on both pieces in order to maximise the surface area.Checking both sides afterwards, the one piece that I couldn't get perfectly flat due to not being able to find my G clamp had allowed some aluminium underneath it. In general though it seems to have worked passably well.
The welds do have faults and there is a lot of spillover on one side. That was because the work wasn't perfectly level and I used too much of the solder. I call it solder because it's really solder, not welding rod. A few minutes with an angle grinder would clean up the spillover on the back if this wasn't just a practice piece.
As far as this weld goes, there are gaps because it was fairly rushed and I had never used my mold nor tried butt-welding flat bar stock before. It was hampered by the lack of a second G clamp but on the whole I am very satisfied. The welds seem solid. When I flexed the bar, the welds did not break. The bar does appear to be straight but curiously there's a step with one bar being slightly out of line. Given that one of the sides of the trough on my mold disintegrated prior to welding I'm not surprised. I'll just need to work more on the mold. Perhaps I need a longer mold. That's doable - I have plenty steel angle I can weld into a former and plenty of the mysterious white gypsum-like powder.
At the moment things are looking fairly positive for making 3 welds like this. I would have to attend to the spill on the front of the test weld as there would be a rivet half way along. Two rivets will secure the bar to the bus body - one on each tongue with the weld stabilizing the join. Needless to say there would be other rivets at other points.
If the metals suppliers would get their acts together and provide 10 foot lengths instead of 8 foot lengths then I wouldn't have to buy two six foot lengths and muck about joining them. I see 10 foot lengths online but the local people won't supply that length. It's a bit like those bargain tyres advertised online. Sure - they're a bargain price but once shipping is paid they're more expensive than buying an ultra-expensive tyre locally.