On Thu, 29 Dec 2016 13:29:57 -0600, Tim Wescott
wrote:

On Thu, 29 Dec 2016 10:19:05 -0800, etpm 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

I did not know you were planning on checking twist with a rotary encoder.

But yes, a level sounds better. If you're going to be looking at the
"analog" display, would a real old-time machinist's level be better, or
are the 'lectronic ones cheaper?
The rotary encoder will measure tilt as will a level. The levels are
much more accurate and have a much finer resolution than any
comparably priced electronic level. To use a rotary encoder to measure
tilt I envisioned a weighted in one spot aluminum disc between a
couple damping magnets.
Eric