A long time ago now, when this blog was in its infancy, I wrote about how I had picked up a cheap manual metal arc welding set from B&Q since I needed to make some tools that would survive within the environment of the furnace. My existing metal-joining technology, silver soldering (aka brazing) would produce joints that would melt like butter at 600 degrees Celsius or so, which is a far cry from the thousand-degree environments I play with...
But as I mentioned slightly earlier, arc welding is easy to get wrong. I learnt from a book, so had only written descriptions to go by, and I was hard put to know what I was doing wrong that made my welds all messy.
Well, today I attended the Insight into Welding course at the Rural Skills Centre, which is near Cirencester, a short drive away from where I live. I had been looking for a welding course for a while - most of the courses I saw advertised at local colleges were formal affairs that took several days and ended up with you taking some kind of assessment, and ending up with an NVQ. All rather formal and constrained.
The Rural Skills Centre, however, does lovely little one-day or several-evening informal courses in all sorts of useful workshop skills. My welding course began with the instructor asking what the seven participant's past experience was, and what they hoped to learn - and then taught us just what we wanted to know, starting at the right level for us. Rather than having a fixed syllabus to be assessed against, we were basically paying to spend a day in a workshop with an experienced welding instructor. Which was perfect!
He quickly sorted out my arc welding problem - I held the electrode too far from the work, so it spattered all over the place and didn't heat the metal properly, thus creating a weld consisting of lots of little blogs sitting on top of the metal rather than bonding into it. Easy once you've seen how it's done properly
So having already got my money's worth before lunchtime, I practiced with the manual metal arc machine for a while, then moved up to try MIG welding - Metal Inert Gas. This is a much fancier setup than arc welding; the machine feeds a metal wire and shielding gas into the work for you when you pull a trigger, rather than you needing to manually control the distance between the end of an unweildy electrode and the work to within a few millimetres. As long as you have the voltage and wire feed speed controls on the machine set correctly for the wire you're using, the metal you're joining, and the kind of join you're doing, it's point and click - just hold the tip of the tool to the metal, pull the trigger, and keep the tip moving along smoothly, and you end up with lovely nice welds. Of course, knowing how to set the controls up right is the hard part, but we were taught foolproof techniques to home in on the correct settings.
So I spent much of the day practising with that, producing various kinds of joins in various thicknesses of mild steel. I'm quite taken by MIG welding - the equipment is a bit more expensive to buy and run than manual metal arc kit, but it produces vastly superior welds, and can be used on aluminium (manual arc can't do that).
But the best process for aluminium is TIG welding. A TIG welder doesn't put any metal out at all - it just produces intense head by driving an arc from a tungsten needle to the workpiece, while spraying the area with shielding gas like a MIG welder does. You have to feed your own extra metal in by hand to make the joint. But it's incredibly neat; the arc is tiny, and still - in the other processes the arc always seems to jump about a bit. The TIG arc was like a little flame a few millimetres long, and underneath it, the metal melted into a shiny puddle. Since it was so small you couldn't go very fast with it, but it produced incredibly neat welds! However, sadly, the TIG welding equipment is quite expensive, since the power supply needs to do some quite specialist regulation to create that easy-to-control neat arc!
So I'm going to keep practising my arc welding - but I'll be keeping my eye out for a MIG welder if I find one cheap or if I get rich... and I certainly wouldn't say not to a TIG if I somehow manage to find one I can afford!