I'm getting ready to build another 18650 pack and wanted to come up with an improved electrode for my Riba spot welder. I really like the one hand ability of the one Rojitor was using. (https://endless-sphere.com/forums/viewt ... 14&t=89076
). This handle might also be useful for microwave oven transformer welders or resistance soldering units.
My Riba welder electrodes worked fine, but takes two hands and a foot to operate. This makes holding the nickel strip in place more difficult and I got cramps in my hands after long welding sessions. The wire was too stiff also.
I measured the existing wire and found it was closest to AWG 4, so ordered some super flexible welding cable that size. Temco has really nice stuff and it comes in a wide variety of AWG and color and they will sell by the foot. They also have battery jumper cables of assorted AWG and length that have ring terminals crimped on the ends.
I started with some sections of aluminum bar stock. The stuff I had lying around was 3/4" x 1/2", so that's what I used. Slightly thinner stuff might work just as well.
I drilled holes to hold the copper electrodes and cross drilled and tapped holes for set screws. Did the same thing on the other end to hold the welding cables. Alternately you could cross drill the bars and use terminals on the ends of the welding cables.
After drilling and tapping the holes, I joined the two pieces using double stick foam tape. Tape adheres very well to aluminum and there is enough surface area that the pieces stay pretty rigid with respect to each other. VHB tape is the best, but for this application about anything similar should work.
The actual electrodes are made from AWG 6 solid copper wire. This was the largest size solid conductor they stocked at my local hardware store. Sold by the foot, so you can make a lot of electrodes for a few dollars worth. Each electrode was cut and placed in my electric drill and spun against a flat file to form the tip.
The electrodes are placed at an angle which allows the tips to get pretty close. Tip spacing can be changed by extending or retracting the electrodes. I made the holes in the bars a bit oversize for the electrodes so they don't get stuck when dented by the set screws. Right now it has a tip spacing of about 4mm.
View of the welding cable entry. I used some pieces of copper tubing cut in half on the top side of the cable to keep it from getting shredded by the bolts.
After assembly, I was going to use some big heat shrink tubing over the handle, but the stuff I had was a bit too small so I settled for electrical tape.
Picture of business end
Not tested yet, but will report back when I get it set up. I may try placing a switch on the handle to replace the foot pedal. There will be some huge induced voltages in the switch wires during a welding pulse, so some kind of protection or isolation will be needed.