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Learning to weld
January 22, 2020
Ten years ago I got the welding bug.
After doing a vocational training course I discovered my aptitude was essentially zero and on-the-job training was considered essential to improvement. Not actually having a welding job in order to be trained on, I did the best I could, assigning myself simple tasks and destructively testing my horrible creations. This involved buying my own welder, which was an education in itself. After about a month of ruining perfectly good scrap metal I got to the point where I was able to reliably produce all the welds I had learnt - without defects.
My next purchase was a bucket pump so I could pressure test a range of creatively welded bits of steel. This a really cheap piece of kit that you can get just about anywhere, and it completely humbled me. My first attempt was two square bits of scrap welded over the ends of a very thick pipe. It was immediately obvious that all my previous welds had been of insufficient depth, spraying water everywhere at very low pressures.
The other thing about hydrostatic pressure testing metal parts is, it makes the metal wet. Not knowing any better I'd often try to grind out and repair a weld while it was still wet. This worked about 80% of the time, and seeing as I was just trying to improve my technique, that was fine for me. However I did find that "baking" the part after discovering a leak was much more reliable. For a while I was doing this just by putting the part out the sun, later I discovered the joys of hitting it with the blowtorch.
Eventually I produced a nice chunk of mild steel that could hold as much pressure as I could pump into it. What could I do with this artefact of weeks of effort? Not a lot. I installed a shelf in my garage and left it there to slowly rust. Surprisingly, the rust really didn't affect the welds at all - it still held pressure a year or more later. This was a quite heavy bit of metal, so I guess I shouldn't be too surprised. I did five or six different prototypes of this form, and it honestly got a bit repetitive. I could whip up a pressure vessel of similar quality in about 10 minutes and it would hold pressure on the first attempt. Boring.
Around this point I got into welding aluminium sheet. I was using a low end TIG welder, and my goal was to build lightweight pressure vessels, so aluminium seemed like a must have. In retrospect, I should have investigated stainless steel, but the price and availability were horrible, so I settled for aluminium. I also should have tried reproducing my success with steel by starting with thicker aluminium, but I didn't do that either. As a result I produced mostly burn-thru and other defects. I did get a small lightweight tank to hold pressure, but I could never get my success rate up.
Later that year I traded my TIG welder for a MIG and bunch of other metalworking tools. It wasn't a great deal but I was done fiddling around with aluminium. Eventually I moved to a house without a garage and sold everything off.
I still think about welding, and I guess I'll get back into it at some point.
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