You ground the rust away from the top of the table.
Did you place the grounding clamp with the jaw that has the cable bolted to it on the cleaned area or on the underside where it did not get clean?
If it's a brass grounding clamp is the jaw of the clamp that has "this side up" attached to the clean area? This is also the side that the cable bolts into.
If it's a brass clamp is the contact surface clean or does it have arc marks and burned places on it?
Does the cleaned table and the clean (no paint, rust, slag, etc.) item being welded do OK for a while before starting to have problems while welding? Slag and spatter between the item being welded and the table will act like insulation.
Even with a shiny table top the item to be welded can start to vibrate while welding. Amazing as it sounds, the contact point between table and item to be welded will heat up. The metal will expand and move in this tiny area. An arc will be observed as the metals move and when they move far enough the arc is extinguished. Metals move back together and it repeats. This can happen in rapid succession when tig welding and the item being welded starts to vibrate like a door bell without the ding dong.
The electrode holder has been cleaned. Does the electrode fit tightly?
When a ganged or multiple welding machine is used there is usually no problems with the arc knowing which weldor to go to or how to complete a circuit.
Most all of them have a GPS now days.
Big toothy grin!
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