Laser Compound-Slide Angle Setting

[tonyfoale]

Establishing the null y-axis position by setting the cross-slide flush with the apron seems like it might be a bit difficult to reproduce accurately. Even a small error will cause your scale on the cabinet to have a translation error.

Marv,

I think that you are making a mountain out of a mole hill.
Just by feel you could repeat that setting probably to less than 0.1mm, definitely 0.2mm maximum. The translation error on the board would be the same as that error and compared to the ability to repeat the dot position on the drawn line it would be trivial.
If you held a small flat block against the saddle edge you could probably set the cross slide position to better than 0.05mm in seconds. Ones ability to set the cross slide position as per Christophe's method far exceeds ones ability to detect a tiny error between the laser dot and the drawn line. I fear that your method would be an order of magnitude less repeatable.

Christophe et al,

it is a convention that the spindle axis of a machine tool is designated as Z. On a lathe what you have called the X axis should be termed Z and your Y is generally called X. Personally I don't like it but that is the convention and less misunderstandings occur if we all use the same notation.