Home Made Spot Welder

I found this on another forum & decided to have a go myself. If it's welcome here I'd like to let you all know how I've been getting along.

If it's considered too dangerous then by all means delete it, but the usual disclaimers apply.

Here's the YouTube video which sparked it all off (terrible pun I know; "sparked" it all off! )....

Well, I thought, as I've got a couple of old microwave oven transformers knocking about, why not have a try?

One thing I would advise, if you decide to have a go yourself, when you cut off the existing secondary coils from the transformer, leave the tape, or paper, or whatever is keeping them together, on there. If you peel it off you will have little pieces of thin wire all over the place! You'll be finding them for years to come! (Just as I will )

So, following the YouTube video I have created this....



As you can see, I'm getting a steady 4.3 volts, which is supposed to be very good.

I've used some 16mm-square household earth cable, mainly as it's the largest cable I had knocking about (being an ex-electrician probably helps here), it should be good for well over 80 amps in short bursts (it should be able to take 80 amps constant really, depending on which version of the electrical regulations you go by).

I've also been experimenting with crushing the end of a piece of 1/4" gas pipe (commonly used as petrol pipe on stationary engines) for electrodes, but I'm not sure about that yet, I would prefer solid copper electrodes, but I don't happen to have any "knocking about". I might try sliding some 3/16" copper pipe inside the 1/4", in an attempt to make it a little more solid. I'll have a fiddle with that in the future.

This will probably now go to the back of the workshop, until I get bored enough to do some more. Although I've got little else to work on at the moment, so maybe I'll have a little more of a play with it first, see what I can do.

Can I just add unless you have a good knowledge of electrics don't try this at home.

Electricity can kill.

Stu.

stationary stu wrote:Can I just add unless you have a good knowledge of electrics don't try this at home.

Electricity can kill.

Stu.

Sure thing Stu. The YouTube video has a pretty good disclaimer on it, & I wouldn't suggest building one of these unless you actually know what you're doing (if you "think" you know what you are doing then that's probably not good enough ).

Anyway, I did a little more last night. I wanted some solid copper electrodes, so I made some.

I have some 1/4" copper gas pipe, I also have some 3/16" copper gas pipe, after some thinking (don't worry, I was careful ) I realised I also had some pretty thick solid copper wire, it's some 3mm (dia) copper "magnet" wire (otherwise known as enamelled copper wire). This was left over from some experiments I was doing earlier this year....



The 3/16" pipe is a tight fit inside the 1/4" pipe, & needed some shaving off, so I put a short length of it into a drill & used a file to shave a bit off. I also used the action of the drill to get it to fit inside the 1/4" pipe.
The 3mm copper wire (obviously I've scraped the enamel coating off it) is not such a tight fit inside the 3/16" pipe. But, some time ago, my dad bought a crimping tool from a boot sale. He had no idea what it was for & neither did I, but it was very cheap so he bought it....




I think it's for "boot lace" type electrical connectors, but not entirely sure. But, it just so happens one of the settings on it was perfect for crimping this little lot together.

So I've now ended up with 2 electrodes, which are hollow on the shaft but solid at the end. If the hollow shaft proves to be a problem I will fill it with solder....







I've also taken apart my second microwave, which has been knocking about in the boot of my car all summer, so I've now got a spare transformer, although it's smaller than the one I'm using, & a few more bits & bobs to scavenge.

I'm determined to make this completely from junk parts, but I may have to spend out a small amount at some point.