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Jon Elson[_3_]

wrote:

So I was looking at some rotary encoders and a thought occurred to me
that maybe I could make a level with a digital display for checking
lathe bed twist. The highest number of pulses per revolution available
was 40,000. That works out to only .009 degrees. Seems pretty small
huh? But .009 degrees is 36 seconds! That works out to .0016" in 10
inches. My fairly inexpensive precision level shows .0005" in ten
inches. That's ten seconds resolution. And I know it's accurate
'cause I checked it with gauge blocks. I know, overkill, a feeler
gauge would be good enough. I guess I'll stick with the level and just
watch the analog bubble display.
Eric
Lucas made some liquid inclinometers that had a resistive liquid inside and
some traces on a PC board that turned it into essentially a potentiometer
with a plumb weight. Kind of worked. No friction, which is what would make
the mechanical version (weight and encoder) not work very well.

The problem with really sensitive bubble levels (like master precision
levels that resolve better than an arc minute) is they take a long time to
settle, like about 30 seconds.

Taylor Hobson makes an electronic level, called the TalyVel. It resolves to
about 0.2 arc second when new, and settles completely in 2 seconds.

The technique is a very light platform suspended by 5 hair-thin wires. It
has an aluminum plate between two magnets as a damper, and a pair of
inductive proximity sensors that detect the ends of the pendulum.
Works fantastically well, but QUITE expensive. About $7000 for one sensor
and the readout box.

Jon