I just finished my alternator welder. Here are some pictures of the welds. I ended up using a Ford Large case 100amp Alternator. It 'feels' good on 3/16" and 1/4" steel with 1/8" 6010 electrodes and 3/32" 6011 electrodes. Actually it's a bit much for the 3/32" electrode at 2700 engine rpm.
These are 1/8" 6010 at about 2700 engine rpm. It has no problem burning through this 3/16" tube and is actually a bit much for this weld.
The center connection weld is 6011 3/32" at 2700 engine rpm.
Heat marks on the other side of the metal to indicate good penetration.
Yes, the leads come right off the alternator. The high voltage (110 volt) helps to strike the arc. The rectifer diodes are 30amp 200volt each and there are 6 of them. The high frequancy ripple in the DC current really helps to stablize the arc. I am almost wondering if I could do aluminum with a tig torch on this setup due to the high freq. ripple.
The large one is the ford weldernator. This is a picture when it was still under construction so some things are missing as the Delco's tensioner and the main leads off the Ford.
Wiring is SUPER easy if you are just using it as a welder, take your field connection (inner most of the two) and hook it straight to positive. Now hook up your electrode to + and ground your work to the alternator ground..away you weld. It will also serve in charging a totally different electrical system. Yes, it is externaly regulated and regulators are $10 from autozone (choose 1980 Ford Truck). The alternator was $25 as a core from the alternator/starter store and I spent $10 for a pulley and a brush holder/brushes.
Here is a very crude diagram of the electrical system when completed.
The welding with this rig feels so good I am thinking about finding me an 8-11hp briggs and building a protable unit.
So the rheostat alone controls the field when welding? And the regulator is there only if you want to use it for charging at 14.2 volts as well? What value is the rheostat? Do you have a voltmeter hooked up to the welding output while running this?
He is switching out his external voltage regulator and using a rheostat to control alternator output. Also need remote throttle to control engine speed. Using 2 alternators he doesn't have to switch from charging to welding and he has spare alternator. He is using truck's 12V power to excite the alternator.
What is rating of your rheostat? Seems to work ok.
The Rehostat is not yet installed, I am simply providing a straight 13.8 volts to the field right now and using engine rpm for voltage control. The voltage at 2200 engine rpm was 90 and it's about 40 volts at idle, 600 engine rpm. I usually weld at 2700 engine rpm.
The rehostat has to be able to handle at least 4 amps at full load. I will probably use a large volume control with a max rating of 20 ohm or a car light dimmer switch has been used before in a similar setup except it was powering a tig torch.
Engine speed control is going to be VERY hard to remotely control unless I use a very long cable. It will be easier to just have the headlight dimmer switch hooked up to a foot pedal with some long wires and control the field power rather than the engine speed.
I have tried bypassing air into the intake manifold and it works, but only 1300rpm, not the 3000rpm I need. In order to bring rpm up to a usable speed I have to use 2 dimes in between the throttle and the throttle stop. Now i could get really fancy and hook an electro servo type setup to the throttle for remote throttle control, but this gets away from the cheap theme of the project. My truck engine shouldn't hurt itself at 3000 no load rpm and using the dimmer switch is the cheap reliable alternative.
most people just use an air compressor motor, or a gas generator engine to spin the alternator on a cart.
Of course you just size the pulleys appropriately, to spin the alternator at desired rpm.
This guys used a 130 amp alternator, and a headlight dimmer to control the circuit. 130 amp Ford Alternator = Tig Welder
You can get a po-man's cruise control. A locking cable from NAPA. You'll have to rig up a slide or a chain so you'll still have throttle contol with your gas pedal. Do make it bullet proof as stuck throttles suck.
Of course, once you get your dimmer in, you can just put an idle solenoid off a 70's carb to kick your engine idle up.
As to tigging with that, isn't TIG straight polarity? If so, you won't be able to TIG on your vehicle.
I've got a Scott Welder made in the 70's that used a truck alt on a 16hp briggs. It is rated for 200amps DC with a 110dc circuit also. It runs the briggs at 3600rpm and the alt at 9000rpm. The thing worked good when it worked. The problem was vibration and it liked to eat belts.
Basicly they take the 3 phase output from the alt run it through a diode bank and put out DC. By controling the exciter input and/or rpm you ajust output amps.
I used to use it to jump start Semi's in cold weather. I hooked it to the truck battery and brought the rpm up slowly untill I heard the welder engine start to load up, about 1200-1500rpm and the truck would start off of it.
In the low 80's I bought 9 of the welders for $300. in need of repair. I only have 1 left and 1 spare head (alt). I still have the owners manual with schematics and troubleshooting guide.