The tube mitering jig is not yet complete. I have yet to make the parts for keeping the miter cuts at both ends of the tube in phase.

Tube clamp vee block. Currently we clamp the halves of the vee block together with a C clamp. It works well enough that I haven't come up with a more elegant clamp.

To miter the tube the jig is clamped to the table of the milling machine and the rotary table is adjusted to the desired angle.