Original poster: "Dwight Harm by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dwighth-at-traxsoft-dot-com> I'm considering getting some 1/4" OD copper tubing, as that seems to be the preferred primary coil material. How significant is the tube thickness? This will likely be driven by a 12/30 NST for now, but I'd like it to be able to handle something heavier (say 12/60) in the future. Dwight.