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Spot-welding .040" 308L CRES SS rod

crossposted to sci.engr.joining.welding and sci.electronics.design please manage followups intelligently, thanks.

I've fashioned sort of a paper catcher for my Canon printer, with .040 TIG filler rod and duct tape. So I thought it'd be cool to spot-weld it, and so I STFW spotwelders and realized I have a scrap microwave oven (I don't know if it works or not, but I have two others anyway) and access to a machine shop, so I'm contemplating what it would take to make one. I have in mind something on the order of a fat pliers, but insulated. I can get "glass pliers" at McMaster-Carr,

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but I wonder what kind of temp. they'd stand up to - alternatively, does anyone know of either something like that that would handle high temperatures, or from experience, tell me not to worry because the electrode holders only get up to XXX deg. C or something. I've worked with "Garolite," which is basically phenolic - very nice to machine with, but it scorches. But maybe a couple of lumps of copper wouldn't get too hot doing .040 steel wire at 4VRMS.

And, if anybody's done that before, (.040" dia. 308L SS), what kind of amps could I expect? They recommend #4 wire, so I expect maybe close to 100. (hmmm - how many amps does it put out at maggie voltages? How many watts was the oven? Ah, that's it.) 750W @4V = 187.5A. Hm. But for a very short period of time, and that's assuming superconducting 308. I guess I should just do it, and borrow an amprobe. Or watch the joint.

So, can anybody recommend either glass-filled epoxy, garolite, or something else for an electrode holder? And is brass better than copper for the electrodes, because it's harder?

Thanks! Rich

Reply to
Rich Grise
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Magnetron want high voltage at (relatively) low current, so while the transformer core may be worth while to you nothing else will be. To get the high-current low voltage source that you want you'd need to rewind the thing.

The one spot welder I worked with had copper electrodes, and they didn't get that hot -- the point of resistance welding is that the highest resistance point should be the spot that you want welded. Since you're trying to weld stainless this part should be easy. Copper is both highly conductive and tends to conform to the part that you're clamping to.

If you want to weld stainless you will need to have some sort of a neutral atmosphere or a flux. You used to be able to get stainless welding flux, but I don't know if anybody bothers with it anymore.

Reply to
Tim Wescott

Do you have a TIG welder as well as the filler? If so just gently tack it without additional filler.

Ted

Reply to
Ted Edwards

Oh, yeah - that's one of the "easy" parts - cut off the secondary, wind a few-turn secondary of hookup wire, that'll give turns/volt; then wind enough #4 or so to make 4V.

These are a couple of good points. I have to keep reminding myself that copper is, after all, metal, and not wax or modeling clay. ;-)

I'm sure I could get flux at the local weld place; inert gases are no problem because I live in a weld shop. :-) But it'd be a PITA if I had to depend on the company's gases to do personal projects.

Thanks! Rich

Reply to
Rich Grise

What kind of amps and volts would you dial in? We have a TIG (or two or three), but I don't know if the owner would want me to play with it/them. I can make a puddle, but the (first and) last time I did it I melted the guy's tungsten. Luckily, I had read about grinding a new point, so that turned out OK, but I'd need a good coach. I've OA brazed mild steel, with coaching, and I've FCAW'd - at least one item with my welds lasted almost 10 years that I know of, and another was still in service 6 mos after I left that company. It must be butt-easy. ;-)

Thanks, Rich

Reply to
Rich Grise

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