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 s**** 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.