For no particular reason except maybe that it was a challenge, I decided to build a spot welder based on a re purposed microwave oven transformer. I had used a small portable Aston spot welder when I was working as an Industrial Technology teacher here in Australia. However, since retirement I no longer have access to the machine and I believe it has been relegated to a storage shed because no one knows how to use it properly. Anyway, I liked the design and the portability of the little Aston welder and working from memory and three grainy photos that I could find online I was able to recreate the mechanism which opens and clamps the tongs onto the work. I have tested the weld quality and whilst it won't deal with really heavy material or large diameter welds it does work and despite the small weld size it is a practical and useful machine. From the get go, I wanted the machine to look professional and to be neat in appearance. I am posting this here because I spent a lot of time producing three YouTube videos (with two more in the pipeline) and to date none have rated much in terms of views. I wanted others to see how it could be done as a truly engineered design but if I were a "Diresta" or a "Stefan Gotteswinter" I would have had thousands of views by now but as a relative newcomer I guess that is not going to happen.
I made use of a number of technologies to manufacture this design. These were:
3D CAD modelling for designing and verifying the design. I use Autodesk Inventor although I also use Fusion360 if I have to do a lot of CAM.
2D CAD for creating the engineering detail drawings for each part.
3D printing for creating the patterns from which I cast light alloy parts used in the clamping mechanism and the chassis of the front end.
Metal Casting for the more complex parts where strength and durability are important.
CNC machining of some of the slots and pockets in the parts. I also drilled all the cooling holes and a decorative hole pattern in the casing using a generated toolpath.
General lathe and mill machining for the more straightforward features
Laser cutting and etching for making the switch panels and for validating the clamp mechanism. I do this by making a 2D mockup from acrylic sheet so that I don't waste a lot of time on metal parts only to find out that the mechanism doesn't work as I expect it to.
Powder coating for finishing the metal components.
Electrical and electronic control systems for the weld timer, cooling fan and the heavy current switching.
If you would like to see more details about this build you can find all the engineering data over at Thingiverse DIY Spot Welder (Super Scary Weldy Thingy) by Preso - Thingiverse
The videos are on YouTube. I will post the url's here so you don't get distracted by all the funny cat videos.
Part 1
Part 2
Part 3
Please feel free to comment on the videos and the Thingiverse post. Use any or all of the information if you wish. I'm all into sharing and we shouldn't spend all our time reinventing that round thing they put on cars.
Regards,
Preso
Very nice Mike. I've had a spot welder on the to-do list for some time. So far I've been holding out for a 5kVA transformer, maybe I should go for a microwave. Yours does a nice job.
Yes, 5KVA would be nice. I did see a video where one enterprising soul had used a transformer from an old 150 amp arc welder. It turned out to be quite a large build and I wanted something that I could pick up and put away in a storage cupboard when I wasn't using it.
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