MTS 211si grounding problem

To set the stage for my question, I have a new (to me) welding table. For ground connection I cleaned a spot on one of the legs with a grinder and welded a 1-1/2" piece of pipe that I cleaned thoroughly. When MIG welding with the piece to be welded laying on the table, I get a small "tack" weld on the table top. I have tried laying the piece on a length of channel iron and connecting the ground cable to the channel iron. I have connected the ground cable directly to the piece. In every case I can think of I am getting the small "tack" weld. I have checked the nut on the ground clamp itself. I have made sure that the ground clamp is in the "-" connection port. I have checked that the connector block on the inside of the machine is "+". What else can I check? Bad ground cable that should be replaced? Thanks for your help.

The "small tack" comes from a poor connection to your work. It has nothing to do with the machine or cable. You could try sanding the whole surface of your welding table to get a better connection to your work. Mill scale, paint or rust on the table or part to be welded could cause your problem.

You should always ground direct to your item you are welding. You are indirect grounding and loosing a lot of connection and increasing resistance.