RE: [CAD_CAM_EDM_DRO] Digest Number 1463 Laser Levels.

It has been 15 years or so since I was trained in precision optics as used
in precision machinery alignment and I don't know about this days laser
products, But I would like to share a few things we were taught back then.
Most of my experience was involving turbine generator sets in power plants
and nuclear reactors.

In class when we asked about lasers, we were told that they were not precise
enough because beam in the tube would rotate around the filament and thus
the beam was about .025" to .030" wide.
We used Brunson Optical Micrometers that gave relational accuracy of .001"
+/- .0005" and micro levels that were good to 50 millionths. For setting up
machines like lathes and mills we used what we called shaft levels. My
personal equipment was Starrett #98 which I Have a 4", 6", 8', & 12".
Occasionally we used a Master Precision Level which typically were 18" long
and the bottom was cambered, so any overhang needed to be equal.

The microlevel had a very sensitive vial which was adjustable with a thumb
screw and the leg on one end was a micrometer, 1" range, direct reading to
100 millionths. The process to use this, was to set the level assembly on
the 2 points you wanted to check. Set the mike at mid scale .500" and then
level the vial. When the vial is level carefully lift it and set the mike
end where the other and had been. Now use the mike to bring the vial back to
level. The difference above or below the .500 line is the difference of
being level. A micro level could be set up as short as about 12" and as long
as 30 feet. It is (or was) probably the most accurate that would commonly be
used outside a laboratory. The vial was so sensitive the that the heat from
a 2 cell flash light focused of the vial would cause it to move.

I tend to get long winded for which I apologize, but If I just wrote forget
about laser and get a shaft level my view would be summarily rejected.

Bob