Wizard's Sleeve welding supplies?

My understanding of the technical side of welding/welders is pretty low, but I thought arc welders were DC. The possibility of it being AC did occur to me sometime last night, shortly followed by the idea about alternator diodes. This really is a very basic old machine, not even an adjuster knob, just 4 connections on the front, 1 for the earth, and 3 different amp settings.

Stronger electrolyte wouldn't help, the trouble is it's already drawing to much power and overloading the battery charger. It was working great while I had it connected to a set of jump leads and a battery, but the battery didn't last long.

The trouble is that it's quite a big thing I'm trying to de-rust, a 3 foot diameter lawn mower deck. The large surface area is why it needs a lot of power. I didn't have a bucket that big so it's in a makeshift tank in the garden, made from a wooden frame and a budget pond liner.

go down the molasses route then should attract interesting wildlife to the garden too

Yeah I can just imagine going out in the morning to find a half empty tank, and a bloated badger rolling around the lawn!

I did consider molasses, it was very good for cleaning out some petrol tanks, but the lawn mower is really crusty and I thought waiting for it to dissolve would take to long, rather make it fall off in lumps.

Mine is a massive old 90 odd kilo 1940s affair which I am pretty certain is AC. When you take the cover off all that seems to be inside is a mahoosive transformer with a knob to adjust how much overlap there is between the coils. A quick google seems to confirm Russle's advice that cheap modern things are generally DC.

If you are desperate to do this without acquiring any more bits, how about setting up a desk fan or washing machine to drive an alternator…

Joolz,
if you want to escape from the nuisance of having to patch your lawnmower deck together every so often, I'd suggest finding one of these, which have a cast alloy deck...

I picked one up for £5 at the local tip years ago and transferred the engine and other parts over from the relatively new mower on which I'd already had to weld the steel deck.

This one's long gone.
http://www.ebay.co.uk/itm/Hayter-Kestre ... 7675.l2557

But this one is still available.
http://www.ebay.co.uk/itm/HAYTERETTE-HA ... 3a8c1dd722

Thanks Ken but I don't think I fancy one of those for our acre+ of grass. The original plan had been to strip the mower down and get the deck galvanised, I thought it would be preventative maintenance, but turned out I was a few years too late.

Interesting idea about using a washing machine motor to power an alternator, will keep it in mind. Turns out the welder is AC, it should have been the first thing I checked when the DC meter setting gave nothing, am just canabalising an alternator for it's diodes now.

Just incase anyone was wondering, the electrolysis was a success. The diode pack was liberated from the alternator, some wires were snipped, others were soldered in, and it ended up with 9 diodes all working in parallel.



The welder was put on it's lowest setting, and things were connected up with the help of a jump lead. There was a bit of arcing from the clamps, the welder made the same humming noise that it does when you get the rod stuck, but nothing caught fire. It was showing an output of about 20volts, didn't measure the current as it would probably have popped the 10amp multimeter.



Despite the extension lead being fully unwound, the built in trip did cut out a couple of times and most things got warm. The wall socket was warm, the extension lead was warm, the welder was hot the diodes were hot, even the water got warm, and it was distinctly tingly when I put my hand in it.
I gave it a few days before pulling it out and jet washing it, I'm reasonably happy with how it's come out. Less so about the amount of holes in it.

As it emerged.


Rust waiting to be washed off.
http://i686.photobucket.com/albums/vv22 ... 5311b4.jpg
http://i686.photobucket.com/albums/vv22 ... ebdfc3.jpg

And after washing. The rust visible on it all appeared after pulling it from the tank, in the time it took it to dry, and is very light surface rust.



And
http://i686.photobucket.com/albums/vv22 ... f31408.jpg

Now to work out what to do with nearly 300 liters of rusty washing solution.

see molasses is better you could make beer with the residue!