Quote Originally Posted by Gearhead51 View Post
FYI, automotive repair spot welders, are often capable of putting out 10,000 plus amps, have over 1000 lbs of compressive force at the weld point, and normally does a 6mm weld "nugget". The proper testing of a spot weld in the automotive industry is a "tear out" where the weld is torn apart. If the "nugget" stays in tact and the metals tear around it, it is a successful weld. These are often done on scrap panels that have been removed from the damaged area of the car. I don't know if that information is helpful to you or not. I just don't want somebody trying to put a car together using this method if it does not actually offer proper penetration. After training technicians on direct resistance spot welders, I see a few reasons why I wouldn't trust this method until I attempted a tear out.

Tig spot welding is different in many ways, and your point is a little off. It's frequently and safely done in the industry in many applications. You have a shielding gas for one and the time used is up to 10 seconds. It's NO different than a normal weld. A tig welded spot weld will be stronger than an unshielded resistance spot weld anyday. The fusion starts on the start plate and penetrates fully down to the second plate. The resistance spot weld is made between the two pieces and is typically smaller and with less penetration. Properly clamped as Rambozo said, you cna use the spot weld timer to make a nice spot weld....and forget about "tear outs" because the only thing tearing IS the metal around it.

Any good set of clamps provides plenty of clamping force to make a good spot weld.