Author Topic: Welding on clean DC  (Read 2976 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.   ;)


BruceM

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Re: Welding on clean DC
« Reply #93 on: October 12, 2019, 12:20:47 AM »
Mikenash or other welders- I need to draw on your experience as I'm still novice level.  I'm planning a mobile welding table with roughly 2'x4' top.

I've struck out at the 2 area scrapyards looking for suitable material for a welding table top.  The two area suppliers won't sell anything less than 4x8 foot sheet stock.  What I can get is 20 foot lengths of either 4 inch wide 3/8 flat, or 6 inch wide 1/2" flat.  Is 3/8 inch thick enough for a slat type welding table top, or should suck it up and go 1/2 (twice the price)?
« Last Edit: October 13, 2019, 04:06:49 PM by BruceM »

glort

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Re: Welding on clean DC
« Reply #94 on: October 14, 2019, 07:20:43 AM »
Have you rung any engineering/ fabrication shops? They may have offcuts just what you are looking for. I have picked up quite decent size plates out of their scrap bins.

mikenash

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Re: Welding on clean DC
« Reply #95 on: October 14, 2019, 09:46:42 AM »
Hey Bruce.  FWIW I would say 3/8 is heaps heavy enough if it is well-supported by pieces of steel underneath

If you made the top out of inch plate it could probably be completely un-supported.  If you made it from quarter plate it might need support every few inches

If you make it out of 3/8, just by smacking the top around a bit you'll get a feel for what support it needs underneath.  And underneath stuff you can knock up out of any old material lying around as no-one will see it . . .

Be imaginative  :)

EdDee

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Re: Welding on clean DC
« Reply #96 on: October 14, 2019, 10:48:03 AM »
Hey Bruce!

I have (Knocked down to component level) a 20mm thick solid welding surface 6ftx4ft - The reason its knocked down: TOO DAMN HEAVY TO MOVE!!

What I eventually settled on for minor mobility and stiffness (Price too) was a 6x4ft piece of checker plate - 1/4" thick...

4x Pipe legs at the corner, a 6" vice strategically welded into place, and, as a stiffener, 1x125mm wide galvanized lip channel welded underneath down the center of its length - the required braces are on the legs, the stiffener makes it more than adequate... As a bonus, the lip channel makes a handy clamp point for the earth leads....

Obviously, the rough side of the checker/tread plate is not the top of the bench!

With a decent run up and a sore shoulder later, I can move the thing a few inches at a time!!

Regds
Ed
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BruceM

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Re: Welding on clean DC
« Reply #97 on: October 14, 2019, 03:38:14 PM »
Thanks for the good ideas and help, Ed, Mike, Glort.

Yep, mobility does lean one towards a less hefty and cheaper design.  I've got some 4 inch all-locking castors which should do the mobility bit. I just have to come up with something to allow the occasional pounding on the vice anvil...perhaps just a wood or steel lift under the vice end to protect the castors.  I saw some scrap 1 inch threaded rod at the junkyard which gave me ideas but I expect the price of those nuts would make me wince.

I've done my best looking for some sort of scrap piece for a top and have come up dry. No engineering in these parts, and the fence/fab shop doesn't carry much in heavy sheet.

A slat type welding table top I can make from a single 20 foot 3/8 x 4 inch flat stock for $75, so I'll do that and beef it up with supports as needed as MikeN suggests. Some guy's seem to like slat tops- not my first choice but  I can put a piece of Hardyboard over it for non-welding table use.  A table with vise to use outside on the 20'x20' shop apron will be very useful for me.

Thanks for the good thoughts, guys!