CEB Press 6 - Support Clamps - Build Time Data
The support clamp tube should be cut 6" long from rectangular tubing using a abrasive cutoff saw. Note that if using a conventional saw, the hardened seam in the tube will reduce the life of the blade.
The support clamps require one hole cut in the center of one side of each clamp and a nut welded over the hole, with clearance for a bolt to fit through the hole. The bolt is 3/4" in diameter and the hole should be about 1" in diameter. This hole can be cut with a conventional drill, a magnetic drill or with a cutting torch.
The simplest means is to use an oxy-acetylene torch, as the hole dimensions need not be exact - in fact, they need not even be marked, just cut the hole in one side only and use a sample bolt to test the fit. After torching the hole, use the next smaller size tube to insert into the clamp length to insure no slag blockages.
If drilling the holes, do not drill on the tube side with the seam, as this is much harder steel and will drill the bit quickly.
When welding the nut to the tube, thread a bolt into the nut, then insert into the hole and weld in place (this assures alignment).