Spot welder and Mig welder

[cwalker509]

I feel like I am spamming lately with all my questions. I have a mig and have used it for a battery apron replacement and some small patching. Also for SS exhaust using different gas. Will not win any awards but good enough. I know a 480v spot welder is what is really needed for heavy duty spot welding on thicker sections but does a 220v spot welder have a place in major restoration work? Should I just use the mig for everything and be done with it? I was reasonably happy with my rosette welds on the apron replacement. Much more so than my panel welding (grinding).

 

[Steve McMahan]

The problem with spot welders are size. If you look at the size of the equipment OEMs used to build the cars, they had to reach over other pieces of structure. They also had superior clamping force. For our repair parts, it just isn’t practical to use a spot welder. Sure, you might find one or two panels you could maneuver a spot welder to make one or two welds, but not enough to justify the expense. And, property done, MIG welds are just as good, some say better. Just my 2 cents (In a previous life, 45 years ago, I designed spot welder’s for the Muffler and Exhaust pipe industry).

 

[cwalker509]

The problem with spot welders are size. If you look at the size of the equipment OEMs used to build the cars, they had to reach over other pieces of structure. They also had superior clamping force. For our repair parts, it just isn’t practical to use a spot welder. Sure, you might find one or two panels you could maneuver a spot welder to make one or two welds, but not enough to justify the expense. And, property done, MIG welds are just as good, some say better. Just my 2 cents (In a previous life, 45 years ago, I designed spot welder’s for the Muffler and Exhaust pipe industry).

Thanks! Was hoping to save some time but not going to run 480 to my house and then pay more than the car is worth for an industrial spot welder. Figured I would ask. Do you know anything about tig welding replacement panels into place?

 

[Hemikiller]

A Mig will do everything you need for restoration welding. Practice more so you get smoother rosette welds, which will save you a ton of time on grinding. A Dynafile makes quick work of them as well.

As far as spot welders, the hand held units (Harbor Freight, Eastwood) are not even remotely good enough to be used in autobody repair. They have a spring for pressure, which doesn't remotely produce enough clamping force for a proper weld. I've seen people use them on cowls, fender aprons and other critical places that will fail over time or on an impact. A proper spot weld may require several thousand pounds of force.

Body shops use a specialized spot welder designed specifically for the purpose. IIRC, they start around $10k and go up from their based on features. Even then, there are guidelines as to where spot welding can be utilized for panel replacement, and where resistance (Mig) welding is required.

I worked for an ISO9001 company that utilized a fair amount of spot welding in it's products, and we did destructive peel testing once a week for each material combination. If our welds wouldn't pull the kernel out of either of the materials being welded, they failed. I can pretty much guarantee that none of the 120/220 welders can do that.

 

[Steve McMahan]

What Hemikiller said . . .