home made welder?

[meancoyote]

anybody ever heard of making a welder from an alternator? a guy at work was talkin about it today and i am interested. looked on the internet and found a few places selling kits, but i may try and make one from junkyard parts maybe.

[welder19]

If you google it you will come up with some sites documenting how to do it, I would post links but there on my laptop.
They are pretty cool, I plan on making one some day.

welder19

[jimbob]

Originally Posted by meancoyote

anybody ever heard of making a welder from an alternator? a guy at work was talkin about it today and i am interested. looked on the internet and found a few places selling kits, but i may try and make one from junkyard parts maybe.

check out Burden Sales Surplus Center - Hydraulics, Engines, Electrical and More they have all sorts of stuff to build your own welder or anything else

[agsolder]

Popular Science Publishing Co. did their Amateur Craftsman's Encyclopedia in 1937 for guys with lots of spare time on their hands. In it is a piece with some instructions on how to make a welder out of an Model A engine-- no figures given on output, but article indicates maybe 200 amps. Piece assumes ammeter, voltmeter, field rheostat, current selector switch, terminal posts, resistance coil, resistance unit, and various wires and terminals" can be "ourchased all assembled and wired in its angle iron frame."

[meancoyote]

i got a 250 amp alternator today. now i need a gas motor. i wonder what horsepower i need?

[meancoyote]

today i got a onan gas motor. now i need to get some more parts and do something.

[ladysmith]

I've always wondered if would be possible make a sort of welder out of a car battery, jumper cables and a coat hanger. (Don't know why I haven't tried it yet.)

Pam

[evfreek]

Hi meancoyote. Yes, these work. But they are difficult to control. The standard voltage regulation scheme in an automobile alternator tends to keep the voltage constant. This is more appropriate for MIG welding. For stick/TIG welding, constant current is more suitable, so you have to replace the voltage regulator with a homebrew current control circuit. The Internet guru of alternator welders, Grant Stockly took his website down, but it had some great proven circuits for accomplishing this. Grant also did extensive experimentation and showed that motor-alternator combinations, since they operate at higher internal frequencies, would transfer more power at less weight. A typical automobile alternator has a lossy fan and undersized wire, so it is only about 50-60% efficient. One horsepower is 746 watts, and you need at least 1000 wats to make a useful welder. In that case, a 2 HP motor is a bare minimum, and Grant recommended 5 HP. Grant also had a table of more efficient alternators (esp. truck types) along with efficiency ratings. If you are serious, a better quality alternator will make life more pleasant.

Also, there is another gotcha to point out. Most inexpensive automobile alternators have diodes that avalanche at about 50V (foggy memory, maybe this is approximate). This is marginal for welding, especially stick welding. The higher quality ones, especially truck alternators, have higher voltage ratings, since some trucks run on 24 volt systems. Grant had a cool idea for a multiphase voltage doubler circuit to boost the voltage to meet the requirements for plasma cutting. It worked!

Give it a try, if you don't spend too much money. You should be able to get an arc out of it. I once made a homemade welder out of a junk microwave oven. It was a lot of work, and it would not hold a reliable arc. It was useless, even compared to the lowest end buzz box you can find on craigslist for about $100. Alternators are a better platform than microwave ovens.

[evfreek]

Hi Pam. Yes, this does work. Use two batteries in series, and roll a thin layer of damp newspaper around the coathanger to make ersatz 6010. I think it runs DCEP. I use my car's battery, along with a carbon rod from a cheap Everready cell, to weld my thermocouples. Make sure to wear flash goggles if you do this!

[meancoyote]

this alternator came out of a ambulance, the guts look very heavy duty. the motor is a 20 hp motor.