Thursday, August 14, 2008

FrankenSwitch, Part 1

I need two honkin' DPDT switches that can sustain 200+ amps for my arc welder. They are for AC/DC and polarity selection. So I am building some of the type shown in the monster films - knife switches:

No worries, they will be under a cover and therefore shielded when energized.

In this episode will be constructing the pole clips.

Got a length of 1/2" copper water pipe, cut it with a pipe cutter, and hammered it flat. Copper is very malleable and ductile, so this is relatively easy to do. I wore ear muffs because it is loud! Then I bent pieces in vice with hammer to form the clip components:

Soldering copper pipe is not hard, but there is a process. First, I cleaned the copper with soap and water to remove oils. Then I used a wire brush on the parts until they are shiny. Next, I applied flux with a clean chip brush - ideally you use an acid brush, but I didn't have one:

I had to arrange my vise and these vise-grips to keep it all together as I soldered it with MAPP torch. Soldering copper involves heating the center or far side of the joint, and then letting the joint melt the solder on the near side. The solder wicks into the joint and flows to wherever there is flux.

After soldering I washed the clips at my sink under cold water and then soaked and rinsed them in a solution of baking soda and water to neutralize the residual flux. Flux should always be cleaned off after any soldering, brazing, or welding operation. Flux is highly aggressive and will corrode the shit out of damn near any metal. The finished clips - they are now very strong and quite heavy:

What is left is to drill holes for terminal bolts and mounting screws. Next on the list will be the throws (knives) and the center support poles.

more to come...

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