Make your own mig with batteries and inductor ?

Hi chaps,
Looking to do some mig welding but only have single phase power which means I wont be able to generate the currents needed for aluminium 3" plate.
ie. Somewhere around the 150 to 200Amp secondary.
So I'm wondering if anyone has made a mig from a set of car batteries and what size/spec inductor you would use to generate an arc ?
--
Regards
Mike
* VK/VL Commodore FuseRails that wont warp or melt with fuse failure indication
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Might find some ideas here...
http://www.readywelder.com /
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snipped-for-privacy@goodone.com says...

Interesting device, though rather expensive for the amount of hardware in it, there is a local supplier at a small airport about 30Kms away, have sent them email but no reply as yet. Definitely worth taking a closer look at but the price seems awfully high for the parts, I guess they still havent recovered their R&D or exploiting the uniquess of it for as long as they can...
--
Regards
Mike
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says...

Also try asking at sci.engr.joining.welding.....
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Mike wrote:

The inductor won't help overmuch. You need a sustained voltage to keep the arc going and the inductor won't provide that. If you have enough volts to sustain the arc, you have enough to strike it.
If you are trying to use less battery voltage than will sustain a reasonable length of arc, then you can use a small hv invertor with a secondary electrode to sustain it. The sort used to light oil-fired burners works quite well - I've used one with 24v of battery to arc weld using coated electrodes. It's easier than using a regular arc welder as the arc strikes before the rod actually touches the metal.
You could get an inverter-type mig/tig set and bring out the primary DC connections - and connect those to your chain of deep cycle battteries - not car batteries. eg http://www.trojan-battery.com /
However, be very very careful. There is shedloads of power there to kill you thousands of times over and burn your place down in an instant. Plus the usual fire risks of batteries charging. Plus welding using lots and lots of watts - that's why welders need 3 phase supplies. Your bank of batteries is going to empty very quickly.
Can't you just hire a suitable generator/ mobile welder or use gas?
I presume that you mean 3" wide bar and not 3" thick plate?
I prefer gas welding - easier to use a gas welder to heat a mug of soup..
--
Sue


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says...

Sorry I wasnt detailed enough, ie For an inductor to give more voltage than the batteries would supply it would need an interruptor, so that V=Ldi/dt could do its thing. Saw this site http://www.readywelder.com and guessed the little control box was prob a fast high current switch at maybe 1KHz and using the inductance of the cables given the current is high...

mmmm, Thats another idea and I like the potential for it to ease the starting of the arc. Have a regular arc welder but not happy with using it for the Aluminium manifold setup I want to make a proof of concept

I can get lots of cheap car batteries and dont care if they die but then the time and effort carrying them around may not be worth it. I actually do have a 3-phase mig but not in working condition, when I get it fixed I guess I could get an alternate transformer for it. ie. Leave the old one in place, get a companion transformer for single phase that would be at the max of its rating for a single phase supply, and just rewire the secondary into the 3-phase unit and the correct feed for the controls etc.

Yeah there is a lot of potential for bangs, not least of which is the ease with which H2 explodes, and its propensity to stick to static surfaces all over the place and not rise like it does in Hollywood.
Anyone that wants to use H2 with all its safety and energy density issues for terrestrial transport has never done a thermodynamic analysis :(

Other option was going to be a single phase motor to 3-phase alternator, I recall a few units around years ago. All in one, ie Windings on same rotor/stator - no coupling to another spinning part etc. But for that price I can probably get a small s/h 3-phase gen set.
Re plate, yeah meant to say 0.3" and lots of pipe, have done steel mig but never ally mig so will need to experiment a heap, especially if I want to make an aluminium coffee cup... mmmm Start with a dish and layer it up around the top edge each time I want to rewarm it ;)
thanks
--
Regards
Mike
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