NeilC Posted January 30, 2022 Report Share Posted January 30, 2022 Hello all, My first post here... I'm getting started into a TR3A here in Ontario, and had a couple queries... The first curiosity, for me, was how tiny the spot welds are on the tub (body), much smaller than any other old car I've done metalwork on. Likewise, the access to some of them are extremely cramped, for example the spare wheel opening surround. It all makes me wonder at the tiny spot welder arms they must have used at the factory. I don't normally spot weld, but I do plenty of rosette welds, and the small size of these spot welds give me pause - meaning I can't see how I'm going to be able to do a rosette weld in my normal fashion. What do you all generally use to redo these spot welds ? I'm aware of using a stationary timed MIG shot using a spacer tip, e.g. from Eastwood, but I've not used that technique thus far. Secondly, my sheet metal gauge seems to come up with a mix of 19 and 20 gauge metal on the tub. Does that seem right ? Any authoritative info on the sizes ? Thanks and regards, Neil Quote Link to post Share on other sites
stuart Posted January 30, 2022 Report Share Posted January 30, 2022 I have a variety of spot welder arms and tips of all shapes and sizes to be able to get into the various places when replacing panels, The order of assembly when starting from scratch is how the factory managed to do it so well as then you can get to most things, not so easy when replacing only certain sections. You will also find the original factory spots were pretty minimal and only just about 3/16th in size, I tend to go for more welds per inch and slightly bigger as it makes for a stiffer shell. I always use 18SWG for all my repair panels as its much easier to work and weld. Stuart. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 30, 2022 Report Share Posted January 30, 2022 (edited) Welcome Neil. Working with automobile body construction taught me spot welds are not all the same. The engineering practice calls for the spot welder tips to be re-shaped/sharpened after a certain number of welds as they become flatter and larger with use, and the resultant weld is not to specified strength. Spot weld guns in industry may have a counter that disables the gun when a certain number of welds have been done and will require an inspector to check the tips have been re-dressed before the they reset the welding gun’s counter. the variables in spot welding are pressure, contact area, amperage and time. here is an helpful article. https://www.titespot.com/spot-welding-technical-information/ Edited January 30, 2022 by BlueTR3A-5EKT Quote Link to post Share on other sites
NeilC Posted January 31, 2022 Author Report Share Posted January 31, 2022 I appreciate the feedback, thanks. Regards Neil Quote Link to post Share on other sites
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