Talyvel: It turns out that there are two US patents that mostly
describe at least the early versions of the Taylor-Hobson Talyvel
electronic level.

3,081,552 "Suspension Devices" to R. E. Reason, issued 19 March 1963.

3,160,237 "Damping Device" to R. E. Reason et al, issued 8 December 1964.

The fact that the above two patents "partially" describe the Talyvel is
mentioned in US patent 3,902,810, so this may well be it.


The Wyler AG levels are based on capacitance. The relevant US patents
a

4,023,413 "Device for measuring Accelerations, Particularly
Accelerations Due to Gravity" to Stauber, issued 17 May 1977.

5,022,264 "Instrument for measuring Accelerations, Particularly
Gravitation Components for Goinometry", to Stauber, issued 11 June 1991.

Siegfried Stauber was the Chief Engineer of Wyler AG at the time.

http://www.wylerag.com/IMAGES_2008/history.pdf

The picture of Dora Wyler scraping a surface plate reminds me of the
grimy young child hidden behind the machines in in the northern brush
factory.


Both instruments sense tilt by means of a pendulum swinging on a
zero-friction pivot of some kind.

The Taylvel senses pendulum motion by means of variable reluctance and
thus inductance. As the pendulum moves, one air gap widens while the
other gap narrows. The two inductances are compared in an impedance
bridge, yielding null at level. The drive frequency is about 10 KHz.

The Wyler level senses pendulum motion by means of variable capacitance.
As the pendulum moves, one inter-plate gap widens while the other gap
narrows. The two capacitances are compared in an impedance bridge,
yielding null at level. The drive frequency is not stated, but is
probably near to 1 MHz.


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

On Sat, 04 Apr 2009 22:23:03 -0500, Spehro Pefhany
wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.


Best regards,
Spehro Pefhany

They can do that but they're surprisingly pricey.

Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Are you planning to try it? Btw, thanks for the list of patents.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Don Foreman wrote:
On Sat, 04 Apr 2009 22:23:03 -0500, Spehro Pefhany
wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn
Have you considered the liquid type? They claim 5 arc second
repeatability.


Best regards,
Spehro Pefhany

They can do that but they're surprisingly pricey.

I got two of these Lucas liquid levels on eBay for
something like $75. Before I had a chance to do
anything with them, I stumbled onto the Talyvel on
eBay and snapped it up. If anyone wants these
Lucas units, and I have the docs with them, too,
let me know. I'll make you a good deal.

Jon

In article ,
Wes wrote:

Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

The big issue to be figured out is how to handle temperature variations.

The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. I know how, but it would be far too much work. The
patent mentions quartz as a suitable material. So, the question is if
quartz is really necessary. Symmetry may suffice.

The subsequent patent (5,022,264) mentions that the diaphram mass is
made of 0.003" brass foil, which is easy to get and to photoetch. One
can also use stainless steel, but it must be non-magnetic so the Earth's
magnetic field doesn't cause false tilt readings.


Joe Gwinn


PS. The German book came, and I was able to read it well enough to see
that it wasn't all that useful. Most or all circuit diagrams in the
book were clearly wrong (in the sense of being impossible), so I assume
that the authors had no idea how these things actually work. JMG

In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Joe Gwinn

On Apr 5, 6:39*pm, Joseph Gwinn wrote:
In article ,

*Wes wrote:
Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. *In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.

Are you planning to try it? *Btw, thanks for the list of patents.

I am thinking about making a level. *Don't know if I'll really do it. *
Probably depends on how practical an approach I can dream up.

The big issue to be figured out is how to handle temperature variations.

The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. *I know how, but it would be far too much work. *The
patent mentions quartz as a suitable material. *So, the question is if
quartz is really necessary. *Symmetry may suffice.

The subsequent patent (5,022,264) mentions that the diaphram mass is
made of 0.003" brass foil, which is easy to get and to photoetch. *One
can also use stainless steel, but it must be non-magnetic so the Earth's
magnetic field doesn't cause false tilt readings.

Joe Gwinn

PS. *The German book came, and I was able to read it well enough to see
that it wasn't all that useful. *Most or all circuit diagrams in the
book were clearly wrong (in the sense of being impossible), so I assume
that the authors had no idea how these things actually work. *JMG

fused quartz is a good choice. The quartz you can get from burnt out
halogen bulbs. Procedures in experimental Physics by Strong has info
on fused quartz. In another life I made coil springs out of fused
quartz.

Dan

"Joseph Gwinn" wrote in message
...
In article ,
Wes wrote:

Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

snip

If I wanted to make a precision level today - more precise than a
starett/vis master level, then I think I'd do the following

1.erect a perpendicular over the base material - one might use a surface
plate or other optically flat material for the base.

2. drop a penduluum from the perpendicular - longer is better so long as the
perpendicular in fact remains perpendicular

3. place a mirror at the end of the penduluum, and arrange mirrors along the
base to direct beams from a low powered laser. Mirror at base shoudl have
an angled and a straight part

4. use an interferrometer to measure the final centering of the penduluum -
first, just use the laser to roughly center by using the angled mirror to
form an optical amplifier and use a wall, maybe 20 feet away to get the
thing aproximately centered (this should get you to a micro inch or so).
After that, use interferrometry, this will get you to 1/2 wavelenght - so
depending on your choice of emitter, somewhere in the 200 to 500 angstrom
range. With a 1 meter perpendicular, that should give you what .... inverse
sine of 1E-8=?? - well, using small angle aproximation, 1e-8 radians

Is that good enough?

In article
,
" wrote:

On Apr 5, 6:39*pm, Joseph Gwinn wrote:
In article ,

*Wes wrote:
Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. *In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.

Are you planning to try it? *Btw, thanks for the list of patents.

I am thinking about making a level. *Don't know if I'll really do it. *
Probably depends on how practical an approach I can dream up.

The big issue to be figured out is how to handle temperature variations.

The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. *I know how, but it would be far too much work. *The
patent mentions quartz as a suitable material. *So, the question is if
quartz is really necessary. *Symmetry may suffice.

The subsequent patent (5,022,264) mentions that the diaphram mass is
made of 0.003" brass foil, which is easy to get and to photoetch. *One
can also use stainless steel, but it must be non-magnetic so the Earth's
magnetic field doesn't cause false tilt readings.

Joe Gwinn

PS. *The German book came, and I was able to read it well enough to see
that it wasn't all that useful. *Most or all circuit diagrams in the
book were clearly wrong (in the sense of being impossible), so I assume
that the authors had no idea how these things actually work. *JMG

fused quartz is a good choice. The quartz you can get from burnt out
halogen bulbs. Procedures in Experimental Physics by Strong has info
on fused quartz. In another life I made coil springs out of fused
quartz.

I have read Strong's book, which is quite good.

One can buy fused quartz from glass suppliers, and work it like glass.
It is possible for an amateur to make lenses and mirrors, and many
people made their own telescopes. Willmann-Bell publishes books on how
to do this. I can see how to wet grind the fused quartz to make the
spherical depressions in the flat plates of the sensor assembly, and to
drill the holes for the connections to the electrodes. However, vacuumn
depositing the electrodes would have to be sent out. Wet silvering
could be used, but that's another whole process.

For the record, the usual way to grind the depressions would be to use a
machined cast iron tool charged with carborundum grit (or diamond grit)
held in a machiine the moves the tool such that its surface describes a
sphere. Mor modern would be a diamond cup curve-generation tool in a
similar machine.

But I don't have the equipment to handle this, and don't want to get it
for a one-off project. So, I'm thinking of alternatives like two glass
sheets, two brass electrodes, a brass shim diaphram, and a pair of
machined ceramic spacers, assembled with epoxy. Or, two circuit boards
with metal faces inward, two brass spacers, and a brass sheet, assembled
with epoxy. And so on. The temperature and humidity coefficients of
the dielectrics are the big issues, as metals are far simpler.

Joe Gwinn

In article ,
"Bill Noble" wrote:

"Joseph Gwinn" wrote in message
...
In article ,
Wes wrote:

Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

snip

If I wanted to make a precision level today - more precise than a
starett/vis master level, then I think I'd do the following

1.erect a perpendicular over the base material - one might use a surface
plate or other optically flat material for the base.

2. drop a penduluum from the perpendicular - longer is better so long as the
perpendicular in fact remains perpendicular

3. place a mirror at the end of the penduluum, and arrange mirrors along the
base to direct beams from a low powered laser. Mirror at base should have
an angled and a straight part

4. use an interferrometer to measure the final centering of the penduluum -
first, just use the laser to roughly center by using the angled mirror to
form an optical amplifier and use a wall, maybe 20 feet away to get the
thing aproximately centered (this should get you to a micro inch or so).
After that, use interferrometry, this will get you to 1/2 wavelenght - so
depending on your choice of emitter, somewhere in the 200 to 500 angstrom
range. With a 1 meter perpendicular, that should give you what .... inverse
sine of 1E-8=?? - well, using small angle aproximation, 1e-8 radians

Is that good enough?

It's about 100 times better than the Wyler and Taylvel units, which are
only good to one microradian, but portability and applicability to lathe
beds and surface plates could be a challenge.

Perhaps a Sagnac interfereometer would be a suitable tiltmeter? There
is a nice one in a deep bomb shelter and command center in New Zealand:

http://www.ringlaser.org.nz/content/c-2.php

http://en.wikipedia.org/wiki/Sagnac_effect


Joe Gwinn

On Apr 6, 4:29 am, Joseph Gwinn wrote:
In article
,



" wrote:
On Apr 5, 6:39 pm, Joseph Gwinn wrote:
In article ,

Wes wrote:
Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.

Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

The big issue to be figured out is how to handle temperature variations.

The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. I know how, but it would be far too much work. The
patent mentions quartz as a suitable material. So, the question is if
quartz is really necessary. Symmetry may suffice.

The subsequent patent (5,022,264) mentions that the diaphram mass is
made of 0.003" brass foil, which is easy to get and to photoetch. One
can also use stainless steel, but it must be non-magnetic so the Earth's
magnetic field doesn't cause false tilt readings.

Joe Gwinn

PS. The German book came, and I was able to read it well enough to see
that it wasn't all that useful. Most or all circuit diagrams in the
book were clearly wrong (in the sense of being impossible), so I assume
that the authors had no idea how these things actually work. JMG

fused quartz is a good choice. The quartz you can get from burnt out
halogen bulbs. Procedures in Experimental Physics by Strong has info
on fused quartz. In another life I made coil springs out of fused
quartz.

I have read Strong's book, which is quite good.

One can buy fused quartz from glass suppliers, and work it like glass.
It is possible for an amateur to make lenses and mirrors, and many
people made their own telescopes. Willmann-Bell publishes books on how
to do this. I can see how to wet grind the fused quartz to make the
spherical depressions in the flat plates of the sensor assembly, and to
drill the holes for the connections to the electrodes. However, vacuumn
depositing the electrodes would have to be sent out. Wet silvering
could be used, but that's another whole process.

For the record, the usual way to grind the depressions would be to use a
machined cast iron tool charged with carborundum grit (or diamond grit)
held in a machiine the moves the tool such that its surface describes a
sphere. Mor modern would be a diamond cup curve-generation tool in a
similar machine.

But I don't have the equipment to handle this, and don't want to get it
for a one-off project. So, I'm thinking of alternatives like two glass
sheets, two brass electrodes, a brass shim diaphram, and a pair of
machined ceramic spacers, assembled with epoxy. Or, two circuit boards
with metal faces inward, two brass spacers, and a brass sheet, assembled
with epoxy. And so on. The temperature and humidity coefficients of
the dielectrics are the big issues, as metals are far simpler.

Joe Gwinn

Hi Joe,
forgive my ignorant rantings here, but I see there would be a much
more simple way of doing this....
If you don't want to worry about absolute accuracy, ie when leveling a
lathe bed where you are only concerned with differences, then what
about...

Use the capacitance method, ie to each side of centre - a bit of
double sided circuit board would suffice. Suspension for the pendulum
could be out of one of those $1 battery clocks in the junk shops -
use 2 capacitance meters, one each side, set balance. (or use a
comparator, depends on how fancy you want to go)You could do this
every time you use it so drift/temp. compensation would not be a
problem.

So, set to balance/zero/whatever figures it shows at one end of the
lathe, this will establish a datum point, move to the other end, note
difference (in picofarads, whatever) - then use this as a measure of
how far out it is, and which way to go in correcting.

Resolution - no idea. Probably someone smarter than me could do it all
in a PIC micro or similar.

Now, I suspect(sigh...) you could drive a truck through my approach,
but would appreciate constructive comments...

Andrew VK3BFA.

PS - will be away from the PC for at least a week (minor surgery) so
will be looking forward to your reply.

In article
,
wrote:

On Apr 6, 4:29 am, Joseph Gwinn wrote:
In article
,



" wrote:
On Apr 5, 6:39 pm, Joseph Gwinn wrote:
In article ,

Wes wrote:
Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the
Wyler
approach is far simpler mechanically. In either case, the
electronics
part is dead simple by present-day standards, but was a big deal
back in
the 1960s and 1970s.

Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

The big issue to be figured out is how to handle temperature
variations.

The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. I know how, but it would be far too much work. The
patent mentions quartz as a suitable material. So, the question is if
quartz is really necessary. Symmetry may suffice.

The subsequent patent (5,022,264) mentions that the diaphram mass is
made of 0.003" brass foil, which is easy to get and to photoetch. One
can also use stainless steel, but it must be non-magnetic so the
Earth's
magnetic field doesn't cause false tilt readings.

Joe Gwinn

PS. The German book came, and I was able to read it well enough to see
that it wasn't all that useful. Most or all circuit diagrams in the
book were clearly wrong (in the sense of being impossible), so I assume
that the authors had no idea how these things actually work. JMG

fused quartz is a good choice. The quartz you can get from burnt out
halogen bulbs. Procedures in Experimental Physics by Strong has info
on fused quartz. In another life I made coil springs out of fused
quartz.

I have read Strong's book, which is quite good.

One can buy fused quartz from glass suppliers, and work it like glass.
It is possible for an amateur to make lenses and mirrors, and many
people made their own telescopes. Willmann-Bell publishes books on how
to do this. I can see how to wet grind the fused quartz to make the
spherical depressions in the flat plates of the sensor assembly, and to
drill the holes for the connections to the electrodes. However, vacuumn
depositing the electrodes would have to be sent out. Wet silvering
could be used, but that's another whole process.

For the record, the usual way to grind the depressions would be to use a
machined cast iron tool charged with carborundum grit (or diamond grit)
held in a machiine the moves the tool such that its surface describes a
sphere. Mor modern would be a diamond cup curve-generation tool in a
similar machine.

But I don't have the equipment to handle this, and don't want to get it
for a one-off project. So, I'm thinking of alternatives like two glass
sheets, two brass electrodes, a brass shim diaphram, and a pair of
machined ceramic spacers, assembled with epoxy. Or, two circuit boards
with metal faces inward, two brass spacers, and a brass sheet, assembled
with epoxy. And so on. The temperature and humidity coefficients of
the dielectrics are the big issues, as metals are far simpler.

Joe Gwinn

Hi Joe,
forgive my ignorant rantings here, but I see there would be a much
more simple way of doing this....
If you don't want to worry about absolute accuracy, ie when leveling a
lathe bed where you are only concerned with differences, then what
about...

Use the capacitance method, ie to each side of centre - a bit of
double sided circuit board would suffice.

I have been considering circuit board for the outer electrodes, two
glass spacers with the brass shim stock diaphragm between, all held
together with epoxy. (In Europe, the standard would be Araldite.)

Wyler apparently uses fused quartz and invar, but the patent does cover
a design with a stack of sheets glued with epoxy.

The glass sheets can easily be drilled on a drill press with abrasives,
so it will be easy to make the 1" diameter hole for the diaphragm.


Suspension for the pendulum
could be out of one of those $1 battery clocks in the junk shops -

That won't really work. The key innovation in the patent is the use of
the perforated diaphragm as the proof mass. The diaphragm is made by
photoetching, which isn't difficult.


use 2 capacitance meters, one each side, set balance. (or use a
comparator, depends on how fancy you want to go) You could do this
every time you use it so drift/temp. compensation would not be a
problem.

The design in the Wyler patent (4,023,413) uses a differential
capacitor, which is optimum, and is far easier than trying to measure
the two capacitances independently. The classic capacitance-bridge
circuit uses a centertapped transformer to generate the drives to the
outer plates. The moving center plate will have zero voltage when that
plate is centered. The balanced configuration causes the non-varying
part of the capacitance to cancel out, allowing the varying part to come
out loud and clear.

I have built such circuits before, and they are very stable and
well-behaved. The transformer is easily built using a ferrite cup core,
which can also be part of the drive oscillator. The exact frequency is
not important.

The subsequent digital sensor from Wyler does measure the two
capacitances independently, and uses their ratio. There is a patent,
but I don't have the number at hand.


So, set to balance/zero/whatever figures it shows at one end of the
lathe, this will establish a datum point, move to the other end, note
difference (in picofarads, whatever) - then use this as a measure of
how far out it is, and which way to go in correcting.

Initial balance of the sensor would be mechanical, being a set of
leveling screws. Given the difficulty of coming up with a reference
surface that's exactly horizontal (to less than 0.1 arc seconds) in a
home shop, the approach will be to swap ends and adjust for equal
deviations from zero. Ultimately, one can use the sensor to adjust the
surface plate to exact horizontal and the sensor to exact adjustment, in
a converging cyclic process.


Resolution - no idea. Probably someone smarter than me could do it all
in a PIC micro or similar.

Transformer-driven capacitance bridges with synchronous detectors are
*very* good, and the PIC can do no better. I was imagining a purely
analog approach.


Now, I suspect (sigh...) you could drive a truck through my approach,
but would appreciate constructive comments...

Andrew VK3BFA.

PS - will be away from the PC for at least a week (minor surgery) so
will be looking forward to your reply.

Good luck with the surgery.

Joe Gwinn

In article ,
Don Foreman wrote:

On Sun, 05 Apr 2009 13:42:14 -0400, Joseph Gwinn
wrote:

In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Joe Gwinn

Have a look at
http://www.spectronsensors.com/datas...S-105-2704.pdf

Not bad. The resolution is up there, but the repeatability is 0.0008
degrees, or 2.9 arc seconds, versus 0.1 arc seconds. Better than 5 arc
seconds, but still. This is why people bother with pendulum tiltmeters.

Joe Gwinn

Joseph Gwinn wrote:
In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn
Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.
Believe me, .1 arc seconds is AWFULLY sensitive.
I can walk from one end of my Sheldon lathe to the
other and tilt it a full arc second by deflecting
the concrete floor.
So, unless you are aligning turbo-alternator sets
in nuclear power plants, you have no need for such
sensitivity. Possibly because my Talyvel is old
and hasn't been to the factory in 20+ years, it
also drifts. If I am going to be doing anything
precise, I turn it on and let it "warm up" for
5-10 minutes while I am setting up. Then it is
pretty stable. It may still drift a full arc
second or so per hour, may be temperature changes
as I handle it a lot when checking surfaces.

Jon

Joseph Gwinn wrote:


The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. I know how, but it would be far too much work. The
patent mentions quartz as a suitable material. So, the question is if
quartz is really necessary. Symmetry may suffice.

The Talyvel is housed in a cast aluminum frame,
with probably stainless parts inside holding the
platform. The platform can be tilted with two
micrometer knobs on top to compensate for
intentional tilt. When you screw them both down,
it locks the pendulum.

I think fused silica is totally insane, the
thermal drift of my unit is really quite small.

Jon

On Tue, 07 Apr 2009 00:02:58 -0400, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Sun, 05 Apr 2009 13:42:14 -0400, Joseph Gwinn
wrote:

In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Joe Gwinn

Have a look at
http://www.spectronsensors.com/datas...S-105-2704.pdf

Not bad. The resolution is up there, but the repeatability is 0.0008
degrees, or 2.9 arc seconds, versus 0.1 arc seconds. Better than 5 arc
seconds, but still. This is why people bother with pendulum tiltmeters.

Joe Gwinn

I thought it was better but you are correct.

2.9 arc seconds is about 14 microinches per inch or .00014" in 10".
Will you post your pendulum design and results as time goes on,
please? Interesting project!

In article ,
Jon Elson wrote:

Joseph Gwinn wrote:


The original Wyler unit (described in 4,023,413) may be made of fused
quartz, which would be easy for a big company like Wyler to do, but a
problem for me. I know how, but it would be far too much work. The
patent mentions quartz as a suitable material. So, the question is if
quartz is really necessary. Symmetry may suffice.

The Talyvel is housed in a cast aluminum frame,
with probably stainless parts inside holding the
platform. The platform can be tilted with two
micrometer knobs on top to compensate for
intentional tilt. When you screw them both down,
it locks the pendulum.

I assume that the foot is cast iron.

How sensitive is the unit to magnetic fields?

Are there any patent numbers on the unit or in its documentation?


I think fused silica is totally insane, the
thermal drift of my unit is really quite small.

Swiss precision! Must be zero drift!

Actually, making something out of fused quartz and invar is easy for an
optics shop, and the Wyler tilt sensor has only three parts requiring no
adjustments, so it may well be cheaper to make than the Taylvel sensor
unit.

Joe Gwinn

In article ,
Jon Elson wrote:

Joseph Gwinn wrote:
In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Joe Gwinn
Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Believe me, 0.1 arc seconds is AWFULLY sensitive.
I can walk from one end of my Sheldon lathe to the
other and tilt it a full arc second by deflecting
the concrete floor.

I like it! I bet you can detect the house swaying in the wind as well.


So, unless you are aligning turbo-alternator sets
in nuclear power plants, you have no need for such
sensitivity.

Probably the turboalternator twists the thicker floor of the power
station just as much as your lathe does to your basement floor.

One wants instruments to be at least ten times more accurate than what
is being measured, so the instruments don't limit the measurement.


Possibly because my Talyvel is old
and hasn't been to the factory in 20+ years, it
also drifts. If I am going to be doing anything
precise, I turn it on and let it "warm up" for
5-10 minutes while I am setting up. Then it is
pretty stable. It may still drift a full arc
second or so per hour, may be temperature changes
as I handle it a lot when checking surfaces.

No, the drift is built in, a matter of temperature coefficients and
residual deviations from symmetry. Aging has little to do with it. I'm
glad to know the rough magnitude.

While handling, temperature gradients may be the issue, as gradients
cause transient asymmetry. A wooden handle may be in order to cut down
on handling-induced thermal drifts. Or at least cover the existing
handle with the cloth tape used on bicycle handles.

One thing the fused-quartz Wyler unit is used for is long term
monitoring of such things as bridges, where the temperature drift of the
Taylvel would preclude this use.


If my only reason were to measure tilt, I would just monitor evilbay for
a Taylvel. I may yet do this. (I saw three Taylvel electronics boxes
yesterday, but "as is" and no sensor.)

But this is a Project, and if I am going to go to that much effort, the
pendulum units are far more interesting, and accurate.

Joe Gwinn

In article ,
Don Foreman wrote:

On Tue, 07 Apr 2009 00:02:58 -0400, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Sun, 05 Apr 2009 13:42:14 -0400, Joseph Gwinn
wrote:

In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back
in the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Joe Gwinn

Have a look at
http://www.spectronsensors.com/datas...S-105-2704.pdf

Not bad. The resolution is up there, but the repeatability is 0.0008
degrees, or 2.9 arc seconds, versus 0.1 arc seconds. Better than 5 arc
seconds, but still. This is why people bother with pendulum tiltmeters.

Joe Gwinn

I thought it was better but you are correct.

If one were to build an electrolytic level, this would be a good sensor
for it. The electronics are pretty simple. But I assume that one must
use only AC currents for sensing angle, a slight complication.


2.9 arc seconds is about 14 microinches per inch or .00014" in 10".
Will you post your pendulum design and results as time goes on,
please? Interesting project!

If I actually do it, sure.

This is one of those few areas where a dead simple gadget can achieve
such precision.


An odd thought: There was a burglar alarm design sold in the 1970s that
used a silicon strain gage glued to the underside of the floor
(especially the joists) to detect a person walking through. The maker
soon disappeared; don't really know why. May have been too fragile or
too temperature sensitive to be practical. (Silicon strain gages were
new then.) Or, too hard to install in an existing building. Or, too
sensitive to wind induced building sway. Or merely too hard to explain.
A precision tilt sensor could do the same thing, and could be installed
in a closet somewhere. The big advantage was that the sensor was not
easily found or approached undetected, and that one could set the
sensitivity to ignore small critters scurrying about and most pets.

Joe Gwinn

On Tue, 07 Apr 2009 09:12:18 -0400, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Tue, 07 Apr 2009 00:02:58 -0400, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Sun, 05 Apr 2009 13:42:14 -0400, Joseph Gwinn
wrote:

In article ,
Spehro Pefhany wrote:

On Sat, 04 Apr 2009 19:50:29 -0400, the renowned Joseph Gwinn
wrote:


As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back
in the 1960s and 1970s.


Joe Gwinn

Have you considered the liquid type? They claim 5 arc second
repeatability.

Yes, I did consider electrolytric types (a bubble level vial with
electronic readout). The pendulum units are a factor of ten better in
resolution and repeatability, 0.1 or 0.2 arc seconds versus 5 arc
seconds. Long term drift is also an issue. It sure would be easier if
the electrolytic sensors were better than they are.

Joe Gwinn

Have a look at
http://www.spectronsensors.com/datas...S-105-2704.pdf

Not bad. The resolution is up there, but the repeatability is 0.0008
degrees, or 2.9 arc seconds, versus 0.1 arc seconds. Better than 5 arc
seconds, but still. This is why people bother with pendulum tiltmeters.

Joe Gwinn

I thought it was better but you are correct.

If one were to build an electrolytic level, this would be a good sensor
for it. The electronics are pretty simple. But I assume that one must
use only AC currents for sensing angle, a slight complication.

Very slight. Recall that liquid crystal displays (as found in a $1.99
multimeter from HF) also require AC excitation.


2.9 arc seconds is about 14 microinches per inch or .00014" in 10".
Will you post your pendulum design and results as time goes on,
please? Interesting project!

If I actually do it, sure.

This is one of those few areas where a dead simple gadget can achieve
such precision.


An odd thought: There was a burglar alarm design sold in the 1970s that
used a silicon strain gage glued to the underside of the floor
(especially the joists) to detect a person walking through. The maker
soon disappeared; don't really know why. May have been too fragile or
too temperature sensitive to be practical. (Silicon strain gages were
new then.) Or, too hard to install in an existing building. Or, too
sensitive to wind induced building sway. Or merely too hard to explain.
A precision tilt sensor could do the same thing, and could be installed
in a closet somewhere. The big advantage was that the sensor was not
easily found or approached undetected, and that one could set the
sensitivity to ignore small critters scurrying about and most pets.

Joe Gwinn

I designed stuff like that in those days. Signal processessing to
reject false alarms was indeed the trick before microprocessors became
common. It's still a good trick, but a lot easier to implement now.

Another approach was seismic. The sensors were geophones developed
for oilfield exploration, basically a dynamic mike with a slug instead
of a diaphragm. We made devices that could sense a man walking from a
distance of several meters, a vehicle from several hundred meters or
a chopper overhead, and it could tell the difference. It used a very
small number of CMOS logic chips (less than half a dozen) to do it.