Several years ago I picked up a machinist bench vice at a yard sale. I mounted it outside on a table. It works nice to hold metal for wire brushing, painting, welding. It sees a little wood working as well. I made sure the screw is hidden up inside the support slide so it is out of the rain and weld splatter. At first it was heavy enough to not bolt down. I saw several at the flea market this week for under $10 an inch. 3-5 inches is plenty heavy.
Since it is an old hunk I do not feel bad about abusing it this way.
Bill D