[Karl]

I'm defining a turntable with a vertical axis. It's easiest to put my reference point at about 135deg off the X axis, 

I don't imagine I can just set the Z value to zero, as that would rotate the vector and give me a bad axis.

i.e. the vector (53.734, 0.118, 0.027) is not equivalent to the robot using (0, 0.118, 0.027).

Instead of doing the math every time to get the correct vector, is there a way to lock the Z rotation to zero? Or am I wrong?

[Albert]

You can add a second coordinate system with respect to the first one and rotate it 135 deg around the Z axis (XYZABC set to 0,0,0,0,0,135). You can then make this new coordinate system the new root point.

You can also modify the tool flange of the turntable in the Parameters menu of the turntable (just add the 135 deg rotation around the Z axis).