Ok, I'm about ready to start replacing sheet metal on a 70 Barracuda that I am building for my daughter. I will be replacing the cowl cap, floor pans, trunk pans, quarters and etc. I would like to come as close as I can to duplicating the factory spot welds as I can. I will be doing the work with a mig welder. Would like to see and here your tips and secrets to making the replacement spot welds look as factory as possible.



Thanks
Dan

Father of the Year.

Good stuff, Dan.

At best a MIG welder can only come close. The only thing that can perfectly replicate a spot weld is a spot welder. A wire brush works good for locating the spot welds, and a spot weld cutter is invaluable. An air chisel is your friend when removing the old metal.

I don't know how accurate it is, but my friend replicates spot welds by twisting a pencil erase in the 2K primer while still wet. It turns out looking really good.

look up the barrel cuda threads. he posted pics of how his guy got the right look during the rebody process.

Dan, that is going to be tough! Recently I was looking online at spot welders & there seem to be units that are not too expensive & look like they'd do the job. I remember using one back in my metal shop class in junior high - it was easy to use & worked great. If I was going to do a major sheetmetal job like this, I would invest in one. Whenever I go to car shows, I look at all the restored cars & I look closely for cars that have had sheetmetal work done so well that you can't tell they are not factory - and that means perfectly duplicated spot-welds! You almost NEVER see that! Good luck & all I can say is I don't know how you did it to have your daughter interested - but my hat is off to you. Neither of my daughters could care less about my Cudas.

with as much, metal as you are doing, thats a lot of time to drill, plug weld with the mig, trying to get the factory look

We recently purchased a Lenco
because we couldn't find a used one at the time..

of course, right after that 2 showed up for sale...

We really like it, Very easy to use
we are practicing, on a 72 Dart
welding in floors, spare tire area.

We bought it mainly to do a 340 Dart> quarter panels, full floor and the Cuda quarter panels.
both these cars wanting factory look welds

When finished, there will be no problem selling the welder.

Try placing a wanted ad> local to you

There is not much inside of one to go bad.
(transformer, timer, relay)
they either work or not.

mostly keep the tips clean

Rick, I'm past getting all the old sheet metal out or off, and yes a wire brush does work well. Tom , I have seen the pencil in the primer done, but I was hoping there was a better solution. I would not be against a Lenco spot welder, but from what I have heard you can't get a strong enough weld. I think the problem is on areas like the pans to the rails where the rail is much thicker metal and you can't get enough penetration to make it structurally strong. Is there any truth to this?

Thanks
Dan

So the lenco doesn't require jaws that limit access such as deep inboard on the floor. You just have to line the 2 leads up and pull the trigger? Very interesting.

Thank you.

May I suggest practicing on some scrap pieces of metal the same thickness as your patch panels. When I do my "SpotWelds" with the MIG on my Duster, I run .023 wire in the gun.Takes a bit of "Practice" to get a good "Rosette" looking weld.... Good luck on your Father-Daughter Project....

I have seen one collecting dust at Mike Ross's shop over at B/E&A Restorations.It's a big professional collision repair unit and he might be interested in selling it.
Gus

I would really suggest evaluating how important having correct looking spotwelds are before I would spend the money and time to try to duplicate them. From someone that has literally performed millions of spotwelds and performed destructive testing on them in a manufacturing environment, I can tell you it isn't as simple as holding a couple tips together on a couple pieces of sheet metal. I've probably cut apart 20 full bodies to test spotweld integrity, so I kind of know a little about them. You can't tell a good spotweld by it's looks, so you are left to using a proper, repeatable process to make strong welds, which is almost impossible in a shop setting.

A good spotweld takes the correct current for the proper length of time, proper tip diameter (to heat the metal without burning it) and alignment, proper clamping pressure, and clean materials CONSISTANTLY to perform. While you can have decent results from the stationary machines with the footpedal - it takes a lot of trial and error to get REPEATABLE results, and they are limited to panels that you can fit between the arms.

Many times in the You Tube videos I see people performing spotwelds with the two handheld contacts, and I see that a lot of the time they have spatter coming from between the panels, which indicates they don't have enough clamping pressure between the tips. Those welds typically WILL FAIL TESTING, due to the panels didn't melt together fully. I don't see how anyone can CONSISTANTLY apply the correct pressure required, which can be 100+ lbs in certain circumstances, with handheld contacts in a shop environment.

I also see people "test" their welds by putting several welds into the ends of two pieces of sheetmetal, and try to pull them apart - LOL. The CORRECT test is 1 weld, and trying to twist the 2 apart - if the weld is good, you will tear a hole out of one of the sheets of metal - a bad one the weld fails. Or a chisel between the sheets to see if the weld pops before the metal tears. Point is, you have to make it fail to test the weld - many good looking spotwelds will fail testing. While they can produce acceptable results under controlled conditions, I don't see how someone could produce consistant spotwelds in a shop environment, especially with the handheld contacts.

If its "looks" you're after then go ahead and spotweld it. If you want it solid and safe, mig plug welds are the ticket.

You stated your using a mig so...Plug weld the panels then use a flat,round metal punch BETWEEN the plug weld areas to dimple the metal for the spot weld look...Vary the striking angle to mix it up and use a backer where needed...

I've heard of people grinding the plug welds flat then using a fresh pencil eraser in the wet paint to replicate the spot welds.