im going to be welding my bodywork on car but say when im doing the floor panels etc, the earth clamp wont be able to clamp to what im welding as cant get to both sides of the floor so were would i clamp it for it to still work ??
Anywhere you can get a decent connection will do, as close as possible to where you're welding.
Just make sure it's somewhere on the body, not a component such as a brake disc, exhaust etc.
The nearest and biggest bit of metal or bolt that is welded or bolted into the car floor or inside sill walls. Clean any paint off first, so the clamp is on bare metal.
There is usually somewhere, but if there isn't, clean a patch of floor and either weld a piece of 2mm or thicker metal to the floor, or drill a hole and bolt the metal to the floor, and then clamp onto the metal.
If you are having difficulty finding a good earth you could always weld a small tag of new metal to the old panel whilst you still have access to both sides of the panel. Close up the panel with your new metal and grind off the tag when you have finished doing the proper work.
My experience of them is that they pick up metal dust and create a poor connection, just a lot of fizzling and sparks, and of no use on stainless or ally of course.