I am new to TIG welding. Next week, I am getting a #9 torch to use. I recently watched a TIG Welding Basics DVD by Ron Covell, and in it he suggests using a piece of copper or aluminum under the practice piece (my practice piece will probably be a piece of 1/8 or 3/16 mild steel) so that I do not inadvertently weld the piece to my table top. Anybody ever done this? If so, what metal did you use, and how thick was it? Thanks.