DIY Laser levelling using webcam and laser level

[pippin88]

Interesting idea John.

3 axes may be enough:
Rotation (few degrees may be enough). Likely the rotation should be clamped after achieving the correct level plane. Rotation adjustment could even be manual.
Cutter up/down (few mm, accurate depth very important).
Transverse (~50mm)

Longitudinal along the rail could be done manually with clamping at each position. This avoids the need for a temporary low backlash longitudinal drive.

Actually, all the movements could be done manually based on software feedback. Light cuts are expected only.

An important point is a fixed mounting place for the laser that allows both rails to be machined / aligned. This may be a bracket fixed to the middle of the machine bed, equidistant to the rails.

(By the way I am keen to see some updates to your epoxy granite mill!)