back in the 80s ,whilst working in a main dealer Ford body shop ,the spot welders at the time were similar to the ones available to the home restorer today.I remember a ford fiesta that had new front wing spot welded on with one of these welders. It was then involved in another front end shunt ,the wings where they had been spot welded popped off way too easy!. this was put down the technicians incompetence,not the equipment. over the years I have often removed panels that have been fitted in large bodyshops ,and the spot welds have no were near the factory weld strength. Today, insurance approved Bodyshops have to use approved welders that can reproduce welds near to factory spec .These are inverta welders that use up to 1400 amps (inverta technology increases the power from the standard 3 phase supply)
C type clamping action gives up to 1.300 lbs of pressure ,with water cooled electrodes for continues use with out loss of effiency . these machine now calculate metal type thickness ,and weld nugget size automatically ,this is essential with vehicles now using high strength boron steel. PLEASE STOP YAWNING !
when removing panels from a 50 year old mini ,the spot welds are not as strong as some on cars today ,but are obviously good enough for a Mini .
when I have restored cars in the past ,key areas like sills ,I have plug welded ,say every 4 inch ,and if the appearance of spot welds was required then after the plug welds had been dressed ,then spot welds were then used ,this will confuse future restorers ,but will add extra rigidity ,which some convertible body cars lacked from new .better than seam welding ,which wont look original
good welds can be achieved with 240 v welders ,and some of the problems highlighted were because of poor maintenance and over use of them ,electrodes need regular re,profiling .in the hands of a home restorer this can be better achieved !
Nick
spot welding
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Spider
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Re: spot welding
I would dearly love to buy a spot welder, but when I look at the ratings of most under the $3K AUD, they wouldn't be much good on car panels, especially those of older cars like our Minis due to the thickness of the material. I'd need to spend closer to $10K AUD to get anything worth while I recon, and they are quite big, heavy and need a power supply which would probably stretch the friendship in that dept.
I used to do some service work at one of the local Ford Factories (until it closed it's doors). They had awesome spot welders as you'd expect, and I know only too well the power needed to operate these to achieve the Factory Spot Welds. At the time I was there, they were doing the Ford Laser's (a Mazda 323), however prior to those, they did Escorts (and Galaxys before that) and assembled those shells with the same spot welders. I can't recall the typical rating of them, but it was big, much more than what most medium size workshops would have available (they actually had a Substation mostly dedicated to the welders and that had 2 x 1000 kVA Transformers in it). Each welder had hydraulic arms for clamping the tips together, water cooled of course and their own transformer and timer. I have it in my head that the typical weld current was around 50 000 Amps and 3 to 8 cylces (of the 50 Hz AC Power) depending on what specifically was being welded. I'll have to catch up with Frank and ask him, he used to set them. I guess these days with the modern electronic inverter type welders, they can perform much the same way with less input power.
Another client I have makes hot water systems, they use the mutha of spot welders to weld the socket fittings on to the tanks. Each of these welders are 2250 kVA! They have 7 such welders last time I looked.
I used to do some service work at one of the local Ford Factories (until it closed it's doors). They had awesome spot welders as you'd expect, and I know only too well the power needed to operate these to achieve the Factory Spot Welds. At the time I was there, they were doing the Ford Laser's (a Mazda 323), however prior to those, they did Escorts (and Galaxys before that) and assembled those shells with the same spot welders. I can't recall the typical rating of them, but it was big, much more than what most medium size workshops would have available (they actually had a Substation mostly dedicated to the welders and that had 2 x 1000 kVA Transformers in it). Each welder had hydraulic arms for clamping the tips together, water cooled of course and their own transformer and timer. I have it in my head that the typical weld current was around 50 000 Amps and 3 to 8 cylces (of the 50 Hz AC Power) depending on what specifically was being welded. I'll have to catch up with Frank and ask him, he used to set them. I guess these days with the modern electronic inverter type welders, they can perform much the same way with less input power.
Another client I have makes hot water systems, they use the mutha of spot welders to weld the socket fittings on to the tanks. Each of these welders are 2250 kVA! They have 7 such welders last time I looked.
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NicholasUpton
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Re: spot welding
As my full time job is restoring mini's I invested in a commercial spotwelder about 3 years ago, and my only regret is not doing it sooner. But at the cost of buying a nice running driving mini, it is not economical for the DIY guy. I can reach in and spotweld crossmembers, and assemble custom floor sections for projects in the shop.
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