spot welding 1/8 steel?

I don't have much experience spot welding. I am looking at an assembly that is made from 3 laminated pieces of 1/8" mild steel. Since I
designed the assembly I can choose the fastening method and was wondering if the parts could be reasonably spot welded together. The assembly process would be to first weld two parts together and then weld the last part to the now 1/4" thick assembly. I am also considering blind rivets and screws. But spot welding would obviate any drilling or tapping. And I was thinking someone here would have the practical experience to let me know if this scheme of mine is practical. Thanks, Eric
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I think the floor-mounted spotwelder I used when learning to design and build machines could be turned up to handle steel as thick as 12 gauge, nearly 1/8". You could simulate spot welds by filling punched holes in the top sheet with MIG.
The process is imprecise and may be restricted by the bulk of the electrodes. -jsw
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On 12/2/2017 3:07 PM, Jim Wilkins wrote:

"Plug welding". Would be faster than either screws or rivets, but not as fast as spot welding.
I spot welded 2 1/8" pieces as a test of my home made spot welder and it was nearly perfect. I have not had the occasion to use it on 1/8 for real. But I'm sure that a commercial welder could easily do it.
http://www.mwdropbox.com/dropbox/MOTSpotwelderPrintable.pdf
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snipped-for-privacy@whidbey.com wrote:

The first welds will be easy. Once you start to change thicknesses it might get more interesting. Do you have a spot welder now?
Had fun with a bunch of big spot welders at Fab Tech in Chicago a month ago. The best part when a sales person welded over a weld with some sort of resistance sensing welder. It turned the current WAY up to overcome what it though was shunt of a nearby weld. Got a nice shower of sparks. Surprised the soft carpeting didn't go up in flames. Then we both got shooed away and a Sr. guy gave a lecture and demo.
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On Sat, 02 Dec 2017 11:26:01 -0800, etpm wrote:

The Harbor Freight #45690 spot welder doesn't handle that much, in my experience. I've spot welded a lot of .1" + .1" assemblies with good results but .1" + .125" just tacked instead of welding, and .125" + .125" didn't stick at all. The .1" was cold-rolled and plated steel; the .125" was hot rolled and I probably didn't get enough of the mill scale off to get good enough conduction.
The https://www.harborfreight.com/240-volt-spot-welder-61206.html item is similar to the #45690. #61206 is rated at 2.5 kVA. With twice that power you probably could weld .125" + .125" reliably and quickly, but if you need a good strong three-layer weld I imagine 8 to 10 kVA would be needed. Do you have any factories or shops near you with a good sized spot welder so you could try out your assembly?
--
jiw

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