All great info here so far, heres hoping I can add to this...
Today I was replacing a door skin on a project and started to remove the spot welds along with separating the actual skin from the door frame and as I was looking at a primitive yet effect tool / tools I made and thought I would share. The best part about this is it will probally cost you nothing to make these tools = FREE!!!!
First and foremost saftey!!! G&G glasses and gloves
As for the spotweld remover I have a assortment of drills that I have ground down to as close to zero degree as possible, We all have old drill bits laying around, right?
As for the panel removal tool I took a old pair of Vise-Grips, you guys know the ones that when you goto use them the teeth are almost non-existent and almost always never work the way they were designed to, you want to throw them away but you cant just because....
well I did some modifications to mine and they are priceless to me.
After cleaning the metal, finding the spot welds, countersinking the centers, you then drill just the top portion of the spot weld with a 1/8 SHARP bit not drilling all the way through the panel. Next take the drill bit at almost zero degrees and begin to slowly start to remove the weld itself. I have made a assortment of bits over the years, the size of the weld dictates which bit I will use which is why I like this approach rather than a spotweld removal tool. NOTHING against the tool itself just my own lame opinion, the second photo shows a standard bit and the bit on the right shows one I ground as close to zero degrees as possible. IF YOU HAVE NEVER SHARPENED A DRILL BIT BEFORE YOU SHOULD NOT ATTEMPT THIS. AS ALWAYS BE CAREFUL
As you begin to drill you will be removing the panel closest to you and not distrubing the frame itself, in this case the the exterior panel of the door will not be drilled through at all. After I drilled all the welds it was time to separate the skin from the frame itself. Its best to take some metal and practice drilling first. After all what were trying to accomplish here is separating the two panels with the least amount of destruction. Anyone can take a angle grinder and goto town with nothing but a big mess to show for it.
I always start at the bottom of the door and work up. First starting with a screwdriver to separate beacuse there is room for a screwdriver, when you begin to go up the door space sometimes becomes a issue and with the VG you can separate the two with zero damage to skin or frame. Slowly take the edge of the VG and start to separate. Its always great to see the dirt and rust begin to fall at you feet as the once one piece start to become two.
With the VG you can control the amount of panel separation. The next photo shows the entire panel separate. On the right side you can see how much you can peel back, on the left how with almost no bending, warping or destruction to either the skin or frame you can separate the two. Its almost like a can opener, you dont want to bend the metal as much as I did on the right. I only did it to show showed how much or how little you can bend with the VG. Slowly take small bites with very little pressure applied and separate the panels, almost NO pressure will be needed.