build ya a portaple welder

[missourihick]

I built a portable welder out of junk I had lying around. It is powered by a worn out 12 hp briggs and stratton engine and the power source is a 78 amp gm alternator(not stock) .
The only thing I had to pay for is the diodes I got on ebay for $25,Oh yea I had to pay for the drive belts. I'll try to put a picture on this post. It is a neat little welder,the amps are adjusted by varying the engine speed. It'll run into a dead short for at least a half hour without overheating. If anyone is interested I can email all the pictures you want and I can try to draw out a schematic,remember I said try.

 

[missourihick]

picture of the belts underneath. by the way ,on the alternator the only thing I kept inside was the brush holders everything else was ripped out. It'll weld at about 90 to 110 amps max at about 60 volts open current off a 78 amp alternator. I did get a 120 amp alternator for it ,but I haven't put it together yet.

 

[SPIKER]

Hey looks neat, I sure would like a copy of th ewire dia and any sketches you could make would be gret, I have several old cars laying around ll with good laternators... mostly fords, with external regulators, but I think that self exciting the feilds would be easy enough...

Mark M

ispike@bright.net
/forums/images/graemlins/smile.gif

 

[missourihick]

Heres a low quality schematic

 

[SPIKER]

hey MO:

is the diod pack external to you're design or are you using the internal diode pack (rectifyer bridge) that came with alt? the ones that I've seen before looks very small and unalbe to handle the load that a welder would output. the trigger on the stick is that to power the feild on the alt?

how about using the large gate triggered diodes for the bridge creation and then gate triggering them with the stick remote, ? ony back draw is that once trigger is let off bridge would still flow current untill current is lost by removing stick from surface, would weld with one click and not need continue hold on the trigger... just wondering.

Mark M /forums/images/graemlins/ooo.gif

 

[missourihick]

The internal diodes are way to small to handle the arc. I got my diodes off ebay.SCR rectifiers would be just fine too. I put in the trigger switch to allow a cool down when not welding and also to get rid of the bite you get from the 60 or so volts when changing rods. The cool down button was an after thought,originally I just used the headlight position on the starter switch as a shut off. I left the original rectifier bridge in the alternator only as a junction block ,I folded the copper tabs back away from the OE diodes and the stator connections.

 

[ducky2smoke]

What size rectifier bridge did you use? ducky2smoke Day late,dollar short and a saddle bag full of yesterdays

 

[missourihick]

</font><font color="blueclass=small">( What size rectifier bridge did you use? ducky2smoke Day late,dollar short and a saddle bag full of yesterdays )</font>
Home made rectifier bridge. (6) 50 amp 100 volt diodes

 

[missourihick]

other side of bridge

 

[missourihick]

I f anyone happens to be passing by Macon,Mo. and wants to see /use one of these homebrew welders,you're welcome to try it out. drop me an email thek9makers@lycos.com I check it daily.