Re: Holding Rectangular Aluminum Tubing
Bolt a straightedge down to your table. This could be anything that you have laying around, steel, aluminum, or even MDF or plywood. Take a cut on it to square it to the table. If you put a generous chamfer on the front edge prior to bolting it down, then there is no danger of the endmill going into the table when taking a squaring cut. This gives you a backstop to position the tube against. Then bolt down an end stop, this positions the tube in the X axis. Then clamp the tube down as needed.
Jim Dawson
Sandy, Oregon, USA