The essence of a spot welder is nothing more than a microwave oven transformer rewound to produce low voltage and high current instead of vice-versa. Some people control the pulse-length during the weld with nothing more than their bare hands, while others feel that it’s better implemented with a 555 timer circuit. [Jim]’s version uses a NodeMCU board, which is desperately overkill, but it was on his desk at the time. His comments in GitHub about coding in Lua are all too familiar — how do arrays work again?
Using the fancier microcontroller means that he can do fancy things, like double-pulse welding and so on. He’s not even touching the WiFi features, but whatever. The OLED and rotary encoder system are sweet, but the star of the show here is the 3D printed case, complete with soft parts where [Jim]’s hand rests when he’s using the welder. It looks like he could have bought this thing.
The videos leave no stone unturned in documenting this project. If you’ve got the time, check them out. Highlights include an overview in Part 1, blowing out an SSR and case design in Part 2, smoking wood and a large battery pack time-lapse in part 3. There’s a bonus video going into detail about the electrodes.
Can’t get enough spot welders? We’ve posted too many to list. So to amuse you, we went looking for the earliest spot-welder post on Hackaday. This one from 2005 seems to be the first, but it’s got dead links and no details. Boo bitrot. This spot welder from 2009 is a beauty. Find a better, earlier one? Let us know in the comments below.