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

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?

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

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

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

wrote in message
...
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

http://arstechnica.com/information-t...led-the-waves/
"But take away the fancy GPS shells, and the AGS and its digital fire
control system are no more accurate than mechanical analog technology
that is nearly a century old."

--jsw

On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared to be
either silver or silver plated.

This was used in an old artificial horizon (gyroscopic) (and also
in a gyrocompass) to level it when it first spins up. I picked both up
about 1960 at a surplus place, so it has been around for a while.

IIRC, it was made by Sperry, and likely made for propeller
driven aircraft.

What it does is apply current to a torque motor (ring like
a hollow motor rotor in a permanent magnet field to apply torque at
right angles to the pivot of the gyro to force it to precess until
level. It has outputs on two axes, so between them can zero the gyro
properly rather quickly. (I've seen similar things working with airflow
for air powered gyros -- no electric signals there -- just breathing on
vanes. :-)

Anyway -- I doubt that the dome sensors were anywhere near as
high resolution as our serious sensitive levels, but the
electrical/electronic sensors have been around for quite a while.

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


--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Why not add a 'level arm' - magnify the change easily.

"With a level I can move the world" in reverse.

Martin

On 12/29/2016 12:19 PM, 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

On 30 Dec 2016 03:33:36 GMT, "DoN. Nichols"
wrote:

On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared to be
either silver or silver plated.

The original used mercury

This was used in an old artificial horizon (gyroscopic) (and also
in a gyrocompass) to level it when it first spins up. I picked both up
about 1960 at a surplus place, so it has been around for a while.

IIRC, it was made by Sperry, and likely made for propeller
driven aircraft.

What it does is apply current to a torque motor (ring like
a hollow motor rotor in a permanent magnet field to apply torque at
right angles to the pivot of the gyro to force it to precess until
level. It has outputs on two axes, so between them can zero the gyro
properly rather quickly. (I've seen similar things working with airflow
for air powered gyros -- no electric signals there -- just breathing on
vanes. :-)

Anyway -- I doubt that the dome sensors were anywhere near as
high resolution as our serious sensitive levels, but the
electrical/electronic sensors have been around for quite a while.

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

On Friday, December 30, 2016 at 3:16:34 PM UTC-5, Clare wrote:
On 30 Dec 2016 03:33:36 GMT, "DoN. Nichols"
wrote:

On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared to be
either silver or silver plated.

The original used mercury

I remember hearing that not having a level is easy too. Just tie a bolt onto string and hang it from the ceiling. There you have what is called a plum bob. Its shadow (from the ceiling on down) is an exactly verticle line down, so its right angle is an exactly horizontal one.

On 12/30/2016 2:42 PM, wrote:
....

....

bolt onto string and hang [ing] from the ceiling ...
is called a plum bob. ...

That's PLUMB, not PLUM, the fruit, to be the pedant...

--

Have you checked out
http://wixey.com/anglegauge/index.html
Art

"DoN. Nichols" wrote in message
...
On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared to be
either silver or silver plated.

This was used in an old artificial horizon (gyroscopic) (and also
in a gyrocompass) to level it when it first spins up. I picked both up
about 1960 at a surplus place, so it has been around for a while.

IIRC, it was made by Sperry, and likely made for propeller
driven aircraft.

What it does is apply current to a torque motor (ring like
a hollow motor rotor in a permanent magnet field to apply torque at
right angles to the pivot of the gyro to force it to precess until
level. It has outputs on two axes, so between them can zero the gyro
properly rather quickly. (I've seen similar things working with airflow
for air powered gyros -- no electric signals there -- just breathing on
vanes. :-)

Anyway -- I doubt that the dome sensors were anywhere near as
high resolution as our serious sensitive levels, but the
electrical/electronic sensors have been around for quite a while.

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


--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

wrote in message
...
On Friday, December 30, 2016 at 3:16:34 PM UTC-5, Clare wrote:
On 30 Dec 2016 03:33:36 GMT, "DoN. Nichols"

wrote:

On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four
electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared
to be
either silver or silver plated.

The original used mercury

I remember hearing that not having a level is easy too. Just tie a
bolt onto string and hang it from the ceiling. There you have what is
called a plum bob. Its shadow (from the ceiling on down) is an exactly
verticle line down, so its right angle is an exactly horizontal one.

=================================

A plum(b) bob won't help in an airplane because "down" during a turn
isn't really vertical, and if you think it is your time will be brief.
https://en.wikipedia.org/wiki/Graveyard_spiral

Large warships needed a complex instrument called the Stable Vertical
to tell the gunnery computer which way is up.
http://www.navweaps.com/index_tech/tech-074.htm
It explains the mercury.

-jsw

On Friday, December 30, 2016 at 7:02:00 PM UTC-5, Jim Wilkins wrote:
wrote in message
...
On Friday, December 30, 2016 at 3:16:34 PM UTC-5, Clare wrote:
On 30 Dec 2016 03:33:36 GMT, "DoN. Nichols"

wrote:

On 2016-12-29, Jon Elson wrote:
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.

I've seen similar devices, a small metal dome with about the
curvature of a golf ball (without the dents) which has four
electrical
contacts in a Bakelite insert, and a connection to the metal dome
itself. The liquid was likely something like a saline solution,
selected to not attack the electrodes or the dome. (Both appeared
to be
either silver or silver plated.

The original used mercury

I remember hearing that not having a level is easy too. Just tie a
bolt onto string and hang it from the ceiling. There you have what is
called a plum bob. Its shadow (from the ceiling on down) is an exactly
verticle line down, so its right angle is an exactly horizontal one.

=================================

A plum(b) bob won't help in an airplane because "down" during a turn
isn't really vertical, and if you think it is your time will be brief.
https://en.wikipedia.org/wiki/Graveyard_spiral

Large warships needed a complex instrument called the Stable Vertical
to tell the gunnery computer which way is up.
http://www.navweaps.com/index_tech/tech-074.htm
It explains the mercury.

-jsw

"A plum(b) bob won't help in an airplane...."
Unless you're fueling it with the tanks' dripsticks. There's one in the main gear wheelwell on the keel beam.

Garrett

Jon Elson wrote:
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.

Surveying equipment all has built in levelling doo-dads. One I took apart
had some sort of glass vials filled with something noxious like iodine
that is used to adjust itself to a level position. There were electrodes
attached to the vials but I don't recall the details.

Anybody know what this stuff was?

wrote:


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.
Well, yes, the ordinary "electronic levels" at the hardware store are not
terribly precise.

But, Taylor Hobson also makes a high-end electronic level for millwrights
and such technicians that need to align stuff to serious levels of accuracy.
My Talyvel 3 will resolve .1 arc second, and is quite repeatable to 1 arc
second. It easily detects me walking from one end of my 3500 Lb lathe to
the other, shifts the floor about 1 arc second. The best part is it settles
to a fully damped reading in less than 3 seconds after being picked up and
moved to a different spot. WAY faster than a bubble level.

Jon

On Tue, 03 Jan 2017 14:58:18 -0600, Jon Elson
wrote:

wrote:


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.
Well, yes, the ordinary "electronic levels" at the hardware store are not
terribly precise.

But, Taylor Hobson also makes a high-end electronic level for millwrights
and such technicians that need to align stuff to serious levels of accuracy.
My Talyvel 3 will resolve .1 arc second, and is quite repeatable to 1 arc
second. It easily detects me walking from one end of my 3500 Lb lathe to
the other, shifts the floor about 1 arc second. The best part is it settles
to a fully damped reading in less than 3 seconds after being picked up and
moved to a different spot. WAY faster than a bubble level.

Jon
And way more expensive too. I could build an accurate enough level
with an electrolytic level sensor but that's still way more money than
a good precision level. If I leveled stuff every day I would have a
fast accurate level.
Eric