diy welding mahine cable size?

hi guys

i wanna make a welder. i checked

there the king uses 8 awg copper cables for the winding of the transformers. 

here (namibia) they seem to have only 6 or 10 sqare mm cables.

can i use 1 of those?

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Downunder35m9 months ago

Should be no problem, the thicker the better in terms of getting hot - which needs to be checked during use to avoid the insulation melting away.
For additional cooling, if required you can consider submerging the tansformer in mineral oil.

kefflon (author)  Downunder35m9 months ago

Hi, can I ask you how to connect this? I drew a line for the Live cable (brown) and Neutral (blue). Is this right? And is there a point of putting a Ground or earthing the welding machine? Should that cable be connected to the casing, if its metal?

Live and Neutral.jpg

This way the transformers are connected parallel.
I would prefer aniti-parallel, meaning one blue and brown should be switched.
But with the wire size on the output you will have a hard time welding.
And of course these output ables should be as short as possible, you simply can't use 1.5 or two meters as the voltage drop would be too great and the cable overheats.

kefflon (author)  Downunder35m9 months ago

Thank you. Ill try to connect them anti paralel.

This green and yellow cable was for the winding of the transformers. Should I cut it off outside the transformers and add 2 cables for the two welding handles? What cable size should those be?

Be aware that welding cables are often 10mm² and more.
Even if you add short and thick cable with proper welding attachments the coil in the transformer will still heat up quickly.
You can almost imagine it like the wire in a fuse at home - the cables after it are much thicker making it blow when the current goes too high.
When I played with MOTs for welding I got enough of the troubles and welded two coers together after removing the crossbar.
This way I had enough room for a few decent layers of thick cable.
Don't remember the thickness but it had quite thin insulation and was a very thight fit to get into the core.
Ended up with just 5 turns but was enough for half decent spot welding.

kefflon (author)  Downunder35m9 months ago


Then I use 10 mm and see how many laps I can fit in into the transformers.

The more laps, the more volts, or more power right?

kefflon (author)  kefflon9 months ago

How hot can the machine get without getting damaged? What is an okay working temperature?

kefflon (author)  kefflon9 months ago

If I would submerge the transformer in oil, does the transformer have to be in a container, so it doesn't touch the oil?

kefflon (author)  kefflon9 months ago

sorry, lots of questions.

Temp depends on the insulation.
Enamelled wire can tolerate about 150°C without problems, normal PVC insulation about 60°.
And yes you need a suitable container but the oil is an insulator, so no electrical problem here.

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