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Old 10-26-2013
Brent Swain Brent Swain is offline
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Re: welding and welder options

I use a 100 amp dodge alternator, which I paid $25 for in an auto wreckers , driven by a 10 inch pulley off my main engine.I feed the field from the staring battery ,thru a toggle switch and a 50 watt 12 volt car headlight bulb, to reduce the input to something which wont fry the field windings. To avoid frying the diodes, I put a 120 volt, 60 amp light bulb betweeen the negative and positive output.
You need a lot of RPM , hence the 10 inch pulley. I once had a commercialy buiult welder which used a 3800 rpm wisconsin gas engne and still a 10 ich pulley. That was a lot of RPM! I control the output with the throttle.
I find I get about three years out of the internal diodes which come with the alternator. When they go, I use a much bigger set of external diodes in aluminiumn plates as heat sinks , which never get warm. Dont have the numbers with me at the moment ,but they are common. I have only done, stainless, steel and aluminiumn stick welding with it, but I understand the high frequency of this setup may work well with TIG or MIG.
I have built several anchor winches and stainless woodstoves with it , from scratch, in my cockpit ,while at anchor. The output from it also runs my 120 volt angle grinder and other 120 volt power tools.
I couldn't fit it in my engine compartment, so I made a removeable panel on the side of the engine compartment to run a V belt thru, and mounted the alternator outside the engine compartment. I also mount my watermaker pump there.
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Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"

Last edited by Brent Swain; 10-26-2013 at 11:23 PM.
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