September 11th, 2006

Working on it

Minor update

The past week wasn't terribly productive Minor-wise. I spent a lot of time painting the newly-sandblasted wheels with a brush (five wheels, five coats of paint on each, about 45 minutes per wheel per coat), and I'm certainly glad that's over with. I also spent a couple of evenings turning the fittings that will let me hook my new heater matrix up to Fenchurch's existing hot water pipes (I'm very happy with the result), and spent some time pottering around doing little bits of things like cleaning out the inside of the car. I've made a start on the new heater, but haven't made much progress so far. This is by far the most complicated thing I've ever made from sheet metal, so I'm learning as I go along. So far I've learned that my Dad's MIG welder is too powerful to give a decent weld on 0.5mm thick steel, and even if you do manage to get a blob of weld to stick to both parts of the joint without burning through them, it supplies so much localised heat that just tacking it causes massive distortion, never mind seam-welding it. I'm tempted to wimp out and use pop-rivets, but when I see things that have been pop-rivetted together I often think they look a bit unprofessional and home-made as a result. I'm going to have a try at silver-soldering it instead first to see if I can get a decent joint that way, as I already have the torch, solder, and flux.

Update: I had a try at silver soldering a small test piece of the 0.5mm steel. On the up side, it produced a nice strong joint without distortion (though admittedly a larger piece would be more likely to distort). Easiflo solder and flux lived up to their name and flowed easily along the whole joint once the metal was up to temperature. On the down side, the fire bricks I use for my makeshift hearth are far from ideal (they soak up heat instead of reflecting it back like the stuff they make proper hearths from), and I don't have a sulphuric acid pickling bath, so removing all the tough flux scale from the finished piece is next to impossible. I'm not sure what the effect would be if I didn't remove all the flux, but I suspect it might rot the metal. Nevertheless, I think silver soldering is a better bet for this job than trying to weld it with my dad's MIG welder, and it produces a nicer looking joint than rivets.