The Alternator
You will need a standard GM-Delco alternator to build a welder like this. You cannot use your existing alternator in your vehicle, since you will be modifying it to do something different.
This alternator is standard equipment on most GM vehicles, and Jeeps (at least, mid-80's CJ's). It comes in different current outputs. You will want to find one with the highest output. No, I don't know how to tell them apart.
I got mine at the local U-Pull-It junkyard, from a loaded Bonneville. I assume that a car with power-windows, A/C, etc. will have a higher-output alternator.
Once you have an alternator, you have to take it apart and make a couple simple modifications to it.
Follow the instructions in the diagram above. You need to remove the insulation from one of the bolts on the regulator, and you also need to completely remove the exciter diodes (or diode trio). You do not need to remove the pulley from the alternator to do this, so don't even try. Make a scratch on each end of the case near the middle break-point, so you can put the case back together again the in the same orientation it was originally.
When you go to reassemble the alternator, notice that there is a small hole in the case, where the brush-holder goes. It helps a lot in assembly if you put the brushes in place and hold them there with a drill-bit or something through this hole before you try and stick the main shaft back into the case.
Go back to my On-Board Welder page.