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Spot weld with a tig machine?

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Got 2 pieces of .075 steel to make a end cap that is pressed onto the end of a piece of channel. The end cap on the painted part is not available anymore. There are two spot welds on a diagonal for each set of sheets. Anybody use a TIG machine with DIY electrodes to spot weld? Seems doable if I dial down the current, turn off the gas, and pulse the pedal. My usual method would be to drill a 3/32 hole on one side and drop a small bead, then grind it down.

DSC_0944.jpg

The gold zinc plated piece (top) is all they make now. I milled the slot and opposite side to match the old end cap.

The beige square piece (bottom) will have a radius on each corner.

The old spot weld part is probably gone because some moron bean counter thought the two spot welds made the thing too expensive. Cutting the cost of a $2 piece is all the bean counter is good for.

(I tried to format the pic to appear large, but this funky website software sucks).
 
Won't work, to spot weld you use thousands of amps not a few hundred like on a TIG, electrode shape and presure is what makes it work coupled with power = current squared times the resistance. Ergo HIgh current at the resistance of the 2 sheets touching gets bloody hot!

With tig the best you can do is puddle weld up holes.

Spot welders that can do that are available for less than a grand though.
 
There are piston grip spot welders that run on AC/DC stick and TIG machines. I have a brand name unit from 30 years ago but don't know quite where ATM. Eastwood sells a cheap one. I don't know how much power you'd need for .075.
 
The total thickness would be .075 x 2 = .150.

I was thinking that a reduced current with longer contact time would work. 300 amps dc is still a bit of current.

I remember watching a documentary on explosive welding. Might try it. :nutter: (No I won't)
 
Why can't you use an ordinary spot welder? I bought a cheapo HF for (I think) less than 200 bucks. It works fantastic. Plus you could be creative and make offset contacts. Experiment with dwell time on scrap.
 
No 300 amps is out by a factor of 10, you need at least 3k-6K amps to spot weld thoes thicknesses. Spot welding works by localised heating, to get that you have to dump enough heat fast enough in one spot, 300 amps will just make a mess.
 
^ Never seen it done that way, but if you can turn your pulse settings low enough, should be pretty darn repetitive. Ergo x amps for x secounds and you have a weld you can repeat and reliably test too. Not sure you need a ceramic with stand offs, just notch out a normal one with a diamond wheel. The pliers are a must though + really clean sheet, something typical spot welding partialy gets around by the presure right at the point of the weld.
 
yeah and look at the material thickness there processing compared to what your trying to do!
 
That says max 1.2mm thickness, op wants to weld 75 thou, thats near enough 2mm ie more than 50% more than its rated maximum?
 








 
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