Best way to separate pinch welds

But to put my 2¢ in, i just use a standard drill bit and only drill through one layer, its kind of something you get a feel for overtime, i always use the smallest drill bit i think will work because you can always go up a size if the panels dont wanna split, and center punch because the bits like to walk on the hard weld, then i take a plain thin putty knife and hammer and split the panels apart ,its best to tap light and try and go at it from as many angles as you can, and it doesn't matter if i have a hole in the good panel because thats just a hole to do a plug weld in, a lot of the factory plug welds on my car kind of suck and they really dont take much to separate anyways, strength in numbers i guess... Lol