I just use the $5.00 Harbor Freight spotweld cutter. It's lasted 5 times longer then the Blair i had for $29.00. Just a thought!
FWIW I was having trouble missing the spot but found that if I drove a putty knife between the panels and down to the spot weld the raised bit of metal caused the cutter to center up every time. If I'm taking out a wasted part I just grind it loose, no need to deal with the drill/cutter if it's bound for the scrap pile anyway.
Yep sure fire way to get stuff apart. Sometimes its not just about getting the panels apart, its about saving them and not causing any damage. Like removing a quarter panel from a parts car , you don't want to mess it up. Nor would you want to mess up the sub structure of your car when you take off the quarter to be replaced. I suppose you could grind the old bad one off of your car & drill straight thru the parts car not use a fancy cutter at all. But it all takes common sense; which isn't so common anymore.