On Dec 19, 7:33*am, Mark Rand wrote:
...

Mirror on a stable stand or wall (the surface table would do in my shed). Then
you can look at the wall close to the mill :-)

Mark Rand
RTFM

A mirror that reflects the beam back to a target attached to the laser
should work, with doubled sensitivity, and be visible up close while
you are tapping and tightening the head. You could confirm the
flatness of the mirror by double checking with a square and test
indicator as you move the head down the column.

I just tried it over a 10' path using a 50ths ruler as the target and
equalizing the spot width on both sides of a 1" line, which is easier
than estimating the center. I have to hold the button on this laser
pointer so it wasn't as steady as possible, but I could align it
within 0.050 easily, translating to about 0.005" at the quill. I think
with a clamped instead of hand-held laser I could center the beam
repeatably to 0.020", 0.002" at the quill.

I should have written that the RF-31's Z axis clamping shift was
0.1mm, not 0.5.

jsw