About Us

68droptop · 11-17-2005, 12:14 PM

I just ordered my trunk floor and will be installing it soon. My question is: Has anyone used a spot welder to weld the floor when possible? I can get a spot welder from my father in law. I'm thinking that this would be faster than plug welding with a mig? I know I'll have to use the mig in some places too. I have weld through primer. Is there a problem using that when spot welding? I know the surface has to be clean to use the spot welder, that's why I'm asking.

Thanks,
Jeff

Jack Gifford · 11-17-2005, 11:22 PM

"Spot welder" is slang for resistance welder, which places beryllium copper electrodes on both sides of the "spot", then pulses welding current through, melting (and thus welding) the pieces of sheet metal at that spot. A portable resistance welder typically has the two electrodes mounted at one end of hinged jaws- kind of resembles a big pair of pliers- usually about 18" deep and 6-8" high. I've never seen one with huge enough jaws to be able to weld a trunk floor, so I'm not sure what type of welder you're referring to. If it's truly a "spot welder" that can reach the spots to be welded in your trunk, it would be a great way to do it.

68droptop · 11-18-2005, 12:01 PM

He has this welder that has tow handles the you press against the metal and squeez the triggers and it welds them together like the factory spot welds that are on the car. I'm not sure if I'm explaining it right or not.

engineer · 11-18-2005, 03:36 PM

jaws are not long enough to spot weld. use compressed air punch \ flanger to make a lip and punch small holes in panel, then mig \ tig the holes. works faster, cleaner and easier.

Tempest · 11-18-2005, 06:22 PM

I am just finishing my trunk floor replacement (2 out of 3 panels) I found that more time is spent cutting the panels to fit, than plug welding. The welding around the edges is more difficult than the plug welds. I will try to attach 3 pics, #1 is the floor cut out, #2 is the new floor cut and screwed in, and #3 is the new floor welded in.
Take your time cutting the new floor, and the welding should go quickly, and I am not a good welder.
Good Luck and enjoy this step.

68droptop · 11-18-2005, 08:49 PM

Great job Tempest. I'll probably plug weld, but I'm gonna try the spot weld to see how it works too. I'll practice on some scrap first.

Thanks for the replies.
Jeff

Jack Gifford · 11-19-2005, 01:11 AM

I'd never seen a spot welder with two separate handheld electrodes. Might work, but I don't see how you would perfectly align the two, since you can't see them both simultaneously. Let us know how it goes.

oldblueponcho · 11-19-2005, 04:55 AM

Quote:

Originally Posted by 68droptop

He has this welder that has tow handles the you press against the metal and squeez the triggers and it welds them together like the factory spot welds that are on the car. I'm not sure if I'm explaining it right or not.

If I'm reading this right what you're describing sounds like a machine that was in a bodyshop I worked at in the mid 70's. We called it a spot welder also. You held both of the handles on the same side of the panel and it would weld. At least in theory. It was as likely to burn holes as it was to weld. The electrodes (or handles) had to be in a certain distance range, the metal had to be extremely clean, if there was any space between the two pieces , or any number of other things, you burned holes in the panel. I haven't seen one of these wonderous inventions in about 30 years. And I believe there is a very good reason for that. Please do yourself a favour. Use a mig and plug weld it.

Tempest · 11-19-2005, 08:48 AM

One tip, be sure to have some weight, like an old brake drum, on the new floor as you plug weld to the braces. If there is a gap, it is difficult to get a good weld. I have started grinding the welds now and this could take some time, but I will post the completed job when I am finished.
Good luck and enjoy,

68droptop · 11-19-2005, 09:05 AM

Oldblueponcho,

You got it. That's what I'm talking about. If it's that easy to burn through, then I'll just use the mig.

Thanks

400 4spd. · 11-19-2005, 01:30 PM

Quote:

Originally Posted by oldblueponcho

If I'm reading this right what you're describing sounds like a machine that was in a bodyshop I worked at in the mid 70's. We called it a spot welder also. You held both of the handles on the same side of the panel and it would weld. At least in theory. It was as likely to burn holes as it was to weld. The electrodes (or handles) had to be in a certain distance range, the metal had to be extremely clean, if there was any space between the two pieces , or any number of other things, you burned holes in the panel. I haven't seen one of these wonderous inventions in about 30 years. And I believe there is a very good reason for that. Please do yourself a favour. Use a mig and plug weld it.

Ahh, the good old days....
I used to own one of those. It was called a Panel Spotter. It had a green cabinet on wheels and really thick, heavy cables. There was a time (burn) selector on the front and a trigger switch on one of the handles.
And it would require perfect conditions to use without blowing holes in the metal. All it took to screw up were dirty, rough contact tips, bad ground, a trace of paint, or panels that had ANY gap between them.
The only reason I would want one today is for reproducing the look of a factory weld on a replacement piece I had mig welded in.

oldblueponcho · 11-19-2005, 07:29 PM

Thanks 400 that was the name alright. And your description was right on the money, details that I had forgotten. They could actually duplicate factory welds alright, but the holes they burned could be so big I don't think I'd risk using one again. Alright, maybe for the right restoration under the right circumstances with lots of practice.

PMDRACER · 11-19-2005, 08:22 PM

I did the entire trunk floor for a buddy with a '67 GTO. Here's the thread. Lots of pics.

http://216.178.81.108/forums/showthread.php?t=436092

bigblue66 · 11-24-2005, 01:10 AM

Hey 68droptop,

I've seen two flavors of spot welders:
http://www.eastwood.com/shopping/pro...ProductID=1233
and
http://www.eastwood.com/shopping/pro...ProductID=1172

Eastwood sells these. The first is the kind with jaws - forget that. The second might be useful in terms of spot welding. But I just finished replacing the entire trunk and all the floor pans with a MIG welder. I used a combo of plug welds, stitch welds, and regular beads. It's a pretty big job if you are new to body work... at least it was for me. Actual welding time is minimal compared to all the cutting, grinding, fitting, grinding, etc. Learned a lot though.

Good luck,

Pete

Tempest · 11-24-2005, 10:38 AM

Nice job PMDRACER, and great pics. Thanks for sharing that, my job wasn't anything near to what you did. I cut off the flanges that are to be welded to the inner wheel well, as I didn't want to disrupt good metal.
Thanks again for the pics.

Menu

About Us