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Author Topic: Welding on clean DC  (Read 1885 times)

BruceM

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Re: Welding on clean DC
« Reply #90 on: July 14, 2019, 01:52:32 AM »
Here's some pictures of the new 3 battery welder; two 12V marine group 29 and a 6V cart battery, with my custom gapped toroidal choke as arc stabilizer.  The case needed a complete redo to house the third battery.  It's a bit wider, longer, taller and heavier.

I used it this afternoon for some welding; the push bar for the case was made of some scrap 1" square tubing with 1/16" wall thickness. Since the oxy-acetylene rig is down waiting for a replacement valve body, I tried my hand at stick welding that 1/16 wall tube with 1/16" 6013.  Tricky business but I got it done and a decent job of it.  I switched to 3/32 rod for welding to the 3/16 thick mounting plates, which was much easier since it's really welding 3/16 with brief excursions to the 1/16.

In the first photo you can see the 26 gauge galvanized strip resistor which is used to limit current from the 30V battery series string. In the top (lowest current, most resistance) setting it is lower current than on straight 24V, which is only useful for 1/16" 6013. This strip has worked out very well, and was dirt cheap to build. The lowest positions marked are for 1/8" 7018 or 7014.  The sheet strips have good airflow on the back and front, and stay below 210F so could be directly screwed to the maple stand offs.  I'd planned for silicone washers under screw head and strip, but they aren't needed.

In the third photo you can see the custom clamping attachment I made from some scrap 1/4" steel that allows me to easily move to any power setting.  I marked the positions with the specific rod size and type determined experimentally.  The increments are usefully moderate.  It has a soldered on brass welding connector, and solder tinned faces for the clamping electrical surfaces. It needs some spray paint.  Polarity reversal only requires switching the cable connectors.

As before, the front, rear and side panels come off for battery removal or service.

I do bulk charging with three "smart" 15A max chargers, Schumacher SC1280 6/12V Rapid Battery Charger and 15A Maintainer ($44 ea), one for each battery.  The case is wired with a 6 pin sermos type connector, and now so are the chargers.

Next I'll redo my low power, low EMF maintenance charger, to make it 3 separate chargers as well.  The 6V battery requires 2.2 amps at full charge, so I need to order a 3A linear regulator for that.  It would be really nice to do it with three secondaries on one core but I've got some old small toroidal transformers that I'll use up instead.

I'm very happy with the new version, my welds have improved greatly with the extra power for "whipping" the electrode and the ability to tune the power for rod and material thickness.

Boring for you who can just use a $100 welder, but a big boon for me.





« Last Edit: July 14, 2019, 02:00:44 AM by BruceM »

glort

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Re: Welding on clean DC
« Reply #91 on: July 14, 2019, 09:18:16 AM »

" And in this weeks edition of Garage Beautiful, Bruce shows us how to build a welding trolley into a Piece of art that reflects traditional timber craftsmanship and modern metal sculpting on a work that is not only a show-piece for any shed, but a practical tool as well"........

Very Nice Bruce, as usual.
I have a suggestion that I think you could add these and make this complete and a real show stopper ......



Just replace the wheels with a pair of these 350W 24V wheels, add a couple of controllers for left and right and mount a seat and footrests on the trolley.
You can move the thing anywhere you want with ease, even to your Neighbours place.

Or is that going against the whole idea of this thing.... To make it so freaking heavy no one will EVER want to borrow it!  :0)

With a solar panel, charge controller and an inverter, this thing could be a portable power source as well as a welder.
Seems a shame to have all those big expensive batteries sitting round doing nothing when you are not using the thing for welding.
Least with the wheels you could have your own  EV for round your property!

Nice job mate.

BruceM

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Re: Welding on clean DC
« Reply #92 on: July 14, 2019, 02:48:39 PM »
Yes, portability has suffered now that it's over 200 lbs.  I can still haul it in my trailer, but I'd have to use a come along or block and tackle to winch it up the ramp. Powered wheels would do it but then I'd be out of power before I could start welding.   ;)