Malectrics Spot welder box

thingiverse

Apologies if this explanation is a bit random, I'm writing this at night. I needed to modify the spot welder design to keep my board from hanging off the battery. To do this, you'll need to remove the original potentiometer and replace it with an external one, also moving the display to the lid. The potentiometer I used was a 2W Wire Wound multi-turn 50kOhm. When removing the original pot, note that the wiring is not as expected - the wiper is not the center pin on the original PCB-mounted pot. There's a low frame inside to support three 18650 cells. I used a 9-pin DIN socket for the balance wires of the 18650 cells so that packing and charging can be done without opening the box. The switch I used is a 2-pole 6-way rotary, with one pole for power and one for selection - Auto Pulse or not. Hex holes in the base are 8mm across the flats. A TVS diode was fitted below the board, clamped to ring terminals then heat-shrunk to prevent shorting to the base of the board. The Shottky Diode tabs need drilling to accept bolts and a copper strip is needed to extend it to the other thick wire. I added a 6.5mm mono jack plug on the lid for connection of the foot switch for manual pulse instead of auto-pulse. There are four holes in the base for rubber feet, as well as a keyhole slot for hanging the box on a 'mushroom head' nut. I planned to make a frame to hang the box alongside the battery so the cables would hang downwards. The box screws together with six screws - I think I used No. 4 size 15mm long. You'll need four cable clamps, obviously. Next job is to create a 'pistol grip' with trigger-style gun for single-handed application of probes and manual triggering. Has anyone seen anything suitable? I printed this in low-quality mode on a MakerBot Replicator 2. The quality was good enough, though the top layer of the lid was pretty poor. Don't think I've missed any info - feel free to leave a comment and I'll try and get back to you ASAP. For those who haven't come across this project, the links are below. Marc is a very helpful guy who's helped me in no end of ways.