I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

wrote in message
...
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds.
This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

http://www.hotrod.com/articles/0206s...ur-alternator/
"Most alternators need to spin at about 2,400 rpm at idle, have their
maximum output above 6,000 rpm, and should never exceed 18,000 rpm."

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

How about a timer made from a 555?

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric
Look at the pulley size ratio on your car. Minimum 2:1 - so if the
engine cranks up to only 3000 RPM the alternator is spinning at 6000
RPM.. No problem at all handling 5000.

On Tue, 11 Apr 2017 16:18:16 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

How about a timer made from a 555?

The question wasn't how to make the pulse Gunner - but how to
trasnmit the power pulses to a spinning shaft.

On 2017-04-11, wrote:
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day.

Is this 24 VDC or 24 VAC? Can you *use* AC? If so, mount a
coil around the rotating shaft, and another one close to it to the
stationary surrounds. If you make it well balanced, there should be no
problems for transmitting AC.

I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

I would skip the idea of slip rings, as the electro-magnetic
coupling will last pretty much forever.

Enjoy,
DoN.

--
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 ---

On Tue, 11 Apr 2017 21:33:27 -0400, wrote:

On Tue, 11 Apr 2017 16:18:16 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

How about a timer made from a 555?

The question wasn't how to make the pulse Gunner - but how to
trasnmit the power pulses to a spinning shaft.

Simply use an encoder. to trigger your timer.

http://www.ebay.com/itm/Incremental-...-/171947459869

On Tue, 11 Apr 2017 21:31:10 -0400, wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric
Look at the pulley size ratio on your car. Minimum 2:1 - so if the
engine cranks up to only 3000 RPM the alternator is spinning at 6000
RPM.. No problem at all handling 5000.
That's what I was thinking Clare, but I though I was wrong because
6000 seems awfully fast. Thanks.
Eric

On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:

On 2017-04-11, wrote:
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day.

Is this 24 VDC or 24 VAC? Can you *use* AC? If so, mount a
coil around the rotating shaft, and another one close to it to the
stationary surrounds. If you make it well balanced, there should be no
problems for transmitting AC.

I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

I would skip the idea of slip rings, as the electro-magnetic
coupling will last pretty much forever.

Enjoy,
DoN.
Greetings DoN,
I thought about that but dismissed it because I really don't know how
I would go about doing it. So maybe you could help. Sticking out the
back of the lathe will be a steel tube. Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air. If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better? Since I can supply any
voltage to the stationary coil it seems tome that a 1:1 ratio between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can handle
the minute current? The valve only needs .2 amps to operate so the
wire can be pretty fine. The valve operates on DC but a rectifier can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?
Thanks,
Eric

wrote in message
...
On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"

wrote:

On 2017-04-11, wrote:
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5
watts.
The power will be on for about 4 seconds and off for 7 seconds.
This
on/off cycle will be going on 10 hours a day.

Is this 24 VDC or 24 VAC? Can you *use* AC? If so, mount a
coil around the rotating shaft, and another one close to it to the
stationary surrounds. If you make it well balanced, there should be
no
problems for transmitting AC.

I ahve looked at
slip
rings online but the high speed through hole type are really
spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea?
I
need about 1 inch through the slip rings.
Thanks,
Eric

I would skip the idea of slip rings, as the electro-magnetic
coupling will last pretty much forever.

Enjoy,
DoN.
Greetings DoN,
I thought about that but dismissed it because I really don't know
how
I would go about doing it. So maybe you could help. Sticking out the
back of the lathe will be a steel tube. Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air. If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better? Since I can supply any
voltage to the stationary coil it seems tome that a 1:1 ratio
between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can
handle
the minute current? The valve only needs .2 amps to operate so the
wire can be pretty fine. The valve operates on DC but a rectifier
can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?
Thanks,
Eric

Is there a reason why you can't control the air flow upstream of the
rotary union?
-jsw

On Tue, 11 Apr 2017 21:58:53 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 21:33:27 -0400, wrote:

On Tue, 11 Apr 2017 16:18:16 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

How about a timer made from a 555?

The question wasn't how to make the pulse Gunner - but how to
trasnmit the power pulses to a spinning shaft.

Simply use an encoder. to trigger your timer.

http://www.ebay.com/itm/Incremental-...-/171947459869
How does he get the power to the spinning part???

On Wed, 12 Apr 2017 08:54:19 -0700, wrote:

On Tue, 11 Apr 2017 21:31:10 -0400, wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric
Look at the pulley size ratio on your car. Minimum 2:1 - so if the
engine cranks up to only 3000 RPM the alternator is spinning at 6000
RPM.. No problem at all handling 5000.
That's what I was thinking Clare, but I though I was wrong because
6000 seems awfully fast. Thanks.
Eric
It's fast for a merry-go-round and slow for a jet turbine - - -

On Wed, 12 Apr 2017 20:29:20 -0400, wrote:

On Tue, 11 Apr 2017 21:58:53 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 21:33:27 -0400, wrote:

On Tue, 11 Apr 2017 16:18:16 -0700, Gunner Asch
wrote:

On Tue, 11 Apr 2017 13:46:24 -0700, wrote:

I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day. I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

How about a timer made from a 555?

The question wasn't how to make the pulse Gunner - but how to
trasnmit the power pulses to a spinning shaft.

Simply use an encoder. to trigger your timer.

http://www.ebay.com/itm/Incremental-...-/171947459869
How does he get the power to the spinning part???

Via the not-encoder bits?

--
Newman's First Law:
It is useless to put on your brakes when you're upside down.
--Paul Newman

On 2017-04-12, wrote:
On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:

On 2017-04-11, wrote:
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day.

Is this 24 VDC or 24 VAC? Can you *use* AC? If so, mount a
coil around the rotating shaft, and another one close to it to the
stationary surrounds. If you make it well balanced, there should be no
problems for transmitting AC.

I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

I would skip the idea of slip rings, as the electro-magnetic
coupling will last pretty much forever.

Enjoy,
DoN.
Greetings DoN,
I thought about that but dismissed it because I really don't know how
I would go about doing it. So maybe you could help. Sticking out the
back of the lathe will be a steel tube.

Mild steel, or hardened? Mild would be better.

Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air.

Hmm ... any reason why you can't put the valve on the outside
end of the union? That looks like it (the union) might wear faster than
the slip rings anyway.

If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better?

Hmm ... let's make the part which contains the coil fairly
short, and put a plastic spacer say 1/4" thick or a bit more between it
and the main tube. Let me sketch how I would make it for reasonable
magnetic coupling.. (I'm sure that there are many ways.)

BBBBBBBBBB
XXXXXXXXXXXXXXX XXXXXXXXXXXXXXBBBBBBBBBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXXXXXXXXXXXXXX XXXXXXXXXXXXXXBB
PPPPPPPPPPPPPPP
PPPPPPPPPPPPPPP
PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

This image is only above the centerline of the tube.

If your newsreader is using a proportional space font, the image
will be distorted -- unless you can send it to a printer which has a
fixed-space font like Courier available. Proportional space fonts will
squeeze the ':'s closer together than the 'P', 'S' and 'X' characters.

The second and third row of Ps should end just below the
right-most '|'s

The parts made of ||| are mild steel cups. The one to the left
fits onto a plastic sleeve PPP over the steel sleeve SSS.

The ::: are the ends of wires in the coil wound and glued into
the cup. (With the wire ends brought out though a hole or two drilled in
the bottom wall of each cup.

BBB is a bracket -- steel, aluminum, or perhaps a strong plastic. The
two cups will concentrate the magnetic field fairly well from one coil
to the other. Whether it goes up, or down depends on where you have
something to bolt it to.

voltage to the stationary coil it seems tome that a 1:1 ratio between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can handle
the minute current?

Too few turns will make the inductance too low for the 60 Hz
voltage, even with the steel cups, and will draw too much current from
the supply. At a guess, I would go for perhaps 100-200 turns on each
coil.

The valve only needs .2 amps to operate so the
wire can be pretty fine.

Probably 24 to 30 ga magnet wire. Measure it and calculate how
much area would be taken up by 200 turns to decide how deep to make the
cups. You can use mild steel pipe and bore it out truly round (since
most pipes have an internal weld bead) and then turn a mild steel plate
to press into the pipe. Or -- machine the whole thing out of a mild
steel. If you want it to look nice, and have some, 12L14 machines
nicely. Pipe is usually ugly to machine. :-)

The valve operates on DC but a rectifier can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?

A snubber diode will short half of the AC voltage. Bad news
here. Maybe put one on the DC coil of a relay from whatever is
generating the pulses, and use that to switch the AC into the coil.

On the output coil (between it and the solenoid valve) you'll
want a small bridge rectifier. If you use a plain single diode, you
will only get power for half of each cycle (1/120 second on, 1/120th
second off) which will likely buzz, and you may need to boost the
voltage a bit (maybe 20-50% to get sufficient current into the solenoid
valve.


Thanks,
Eric

You have my thoughts above -- including putting the solenoid
valve outside the union so it does not need to rotate. :-)

Enjoy,
DoN.

--
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 ---

"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.
-jsw

On 13 Apr 2017 03:59:31 GMT, "DoN. Nichols"
wrote:

On 2017-04-12, wrote:
On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:

On 2017-04-11, wrote:
I'm sue someone here can help. I need to get power to a solenoid
operated valve spinning at 5000 RPM. Low power, 24 volts at 5 watts.
The power will be on for about 4 seconds and off for 7 seconds. This
on/off cycle will be going on 10 hours a day.

Is this 24 VDC or 24 VAC? Can you *use* AC? If so, mount a
coil around the rotating shaft, and another one close to it to the
stationary surrounds. If you make it well balanced, there should be no
problems for transmitting AC.

I ahve looked at slip
rings online but the high speed through hole type are really spendy.
Then I got to thinking about the slip rings in alternator. They
certainly can carry enough current but I don't know how fast
alternators typically spin. I do have an old alternator that would
make a good slip ring donor. Anybody know or have a better idea? I
need about 1 inch through the slip rings.
Thanks,
Eric

I would skip the idea of slip rings, as the electro-magnetic
coupling will last pretty much forever.

Enjoy,
DoN.
Greetings DoN,
I thought about that but dismissed it because I really don't know how
I would go about doing it. So maybe you could help. Sticking out the
back of the lathe will be a steel tube.

Mild steel, or hardened? Mild would be better.

Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air.

Hmm ... any reason why you can't put the valve on the outside
end of the union? That looks like it (the union) might wear faster than
the slip rings anyway.

If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better?

Hmm ... let's make the part which contains the coil fairly
short, and put a plastic spacer say 1/4" thick or a bit more between it
and the main tube. Let me sketch how I would make it for reasonable
magnetic coupling.. (I'm sure that there are many ways.)

BBBBBBBBBB
XXXXXXXXXXXXXXX XXXXXXXXXXXXXXBBBBBBBBBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXX:::::::::::: :::::::::::XXXBB
XXXXXXXXXXXXXXX XXXXXXXXXXXXXXBB
PPPPPPPPPPPPPPP
PPPPPPPPPPPPPPP
PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

This image is only above the centerline of the tube.

If your newsreader is using a proportional space font, the image
will be distorted -- unless you can send it to a printer which has a
fixed-space font like Courier available. Proportional space fonts will
squeeze the ':'s closer together than the 'P', 'S' and 'X' characters.

The second and third row of Ps should end just below the
right-most '|'s

The parts made of ||| are mild steel cups. The one to the left
fits onto a plastic sleeve PPP over the steel sleeve SSS.

The ::: are the ends of wires in the coil wound and glued into
the cup. (With the wire ends brought out though a hole or two drilled in
the bottom wall of each cup.

BBB is a bracket -- steel, aluminum, or perhaps a strong plastic. The
two cups will concentrate the magnetic field fairly well from one coil
to the other. Whether it goes up, or down depends on where you have
something to bolt it to.

voltage to the stationary coil it seems tome that a 1:1 ratio between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can handle
the minute current?

Too few turns will make the inductance too low for the 60 Hz
voltage, even with the steel cups, and will draw too much current from
the supply. At a guess, I would go for perhaps 100-200 turns on each
coil.

The valve only needs .2 amps to operate so the
wire can be pretty fine.

Probably 24 to 30 ga magnet wire. Measure it and calculate how
much area would be taken up by 200 turns to decide how deep to make the
cups. You can use mild steel pipe and bore it out truly round (since
most pipes have an internal weld bead) and then turn a mild steel plate
to press into the pipe. Or -- machine the whole thing out of a mild
steel. If you want it to look nice, and have some, 12L14 machines
nicely. Pipe is usually ugly to machine. :-)

The valve operates on DC but a rectifier can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?

A snubber diode will short half of the AC voltage. Bad news
here. Maybe put one on the DC coil of a relay from whatever is
generating the pulses, and use that to switch the AC into the coil.

On the output coil (between it and the solenoid valve) you'll
want a small bridge rectifier. If you use a plain single diode, you
will only get power for half of each cycle (1/120 second on, 1/120th
second off) which will likely buzz, and you may need to boost the
voltage a bit (maybe 20-50% to get sufficient current into the solenoid
valve.


Thanks,
Eric

You have my thoughts above -- including putting the solenoid
valve outside the union so it does not need to rotate. :-)

Enjoy,
DoN.
Greetings DoN,
Thanks for the advice. The reason for the valve is that the rotary
union has only one air passage and I need two for the closer. The
rotary union I am using will last thousands of hours. I know this
because I have used this exact model for thousands of hours. I don't
know why it is but two passsage rotary unions that can handle the air
pressure and speed are about 10 times more expensive than single
passage ones. For liquids, like oil or coolant, two passage rotary
unions have much higher pressure and rpm limits. Anyway, the only cost
effective way to get the setup to work is to do the valving in the
spinning tube. I use DOM tubing for spindle liners and will be using
some for this project. I have another coil question. What if the coils
face each other rather than being concentric? Harder to wind maybe but
it might be easier to mount the stationary coil if it is facing the
moving coil.
Eric

On Thu, 13 Apr 2017 08:52:56 -0700, wrote:


Greetings DoN,
Thanks for the advice. The reason for the valve is that the rotary
union has only one air passage and I need two for the closer. The
rotary union I am using will last thousands of hours. I know this
because I have used this exact model for thousands of hours. I don't
know why it is but two passsage rotary unions that can handle the air
pressure and speed are about 10 times more expensive than single
passage ones. For liquids, like oil or coolant, two passage rotary
unions have much higher pressure and rpm limits. Anyway, the only cost
effective way to get the setup to work is to do the valving in the
spinning tube. I use DOM tubing for spindle liners and will be using
some for this project. I have another coil question. What if the coils
face each other rather than being concentric? Harder to wind maybe but
it might be easier to mount the stationary coil if it is facing the
moving coil.
Eric

I assume you need two air feeds because the closer has a double acting
cylinder. If we can also assume that the closer requires a higher
pressure for clamping than for releasing, then you may be able to use
a single passage union and a sequence valve circuit rotating with the
closer and a 2-pressure supply to the union. When the rotating circuit
sees low pressure it routes the pressure to the closer's release port;
high pressure switches the pressure to the clamp port. In other words,
the union is carrying both the working air pressure and the data
needed to route the pressure to the proper port.

If you're not familiar, there's some info on sequence valves he
http://beta.hydraulicspneumatics.com...educing-valves

--
Ned Simmons

On Thu, 13 Apr 2017 07:35:32 -0400, "Jim Wilkins"
wrote:

"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.
-jsw

what kind of electric motor? I'm assuming a universal motor. What
advantage do you get using a brushed motor with a commutator in place
of the VERY much simpler slip rings?????? Also, with a rotating
transformer the pulse timing for the solenoid is likely going to get
pretty hairy due to the magnetic retention of the cores.

There is really nothing wrong with using slip rings, and it is the
most elegant solution due to it's sureme symplicity. NOTHING he is
trying to do contraindicates using slip-rings.

On Thu, 13 Apr 2017 14:13:20 -0400, Ned Simmons
wrote:

On Thu, 13 Apr 2017 08:52:56 -0700, wrote:


Greetings DoN,
Thanks for the advice. The reason for the valve is that the rotary
union has only one air passage and I need two for the closer. The
rotary union I am using will last thousands of hours. I know this
because I have used this exact model for thousands of hours. I don't
know why it is but two passsage rotary unions that can handle the air
pressure and speed are about 10 times more expensive than single
passage ones. For liquids, like oil or coolant, two passage rotary
unions have much higher pressure and rpm limits. Anyway, the only cost
effective way to get the setup to work is to do the valving in the
spinning tube. I use DOM tubing for spindle liners and will be using
some for this project. I have another coil question. What if the coils
face each other rather than being concentric? Harder to wind maybe but
it might be easier to mount the stationary coil if it is facing the
moving coil.
Eric

I assume you need two air feeds because the closer has a double acting
cylinder. If we can also assume that the closer requires a higher
pressure for clamping than for releasing, then you may be able to use
a single passage union and a sequence valve circuit rotating with the
closer and a 2-pressure supply to the union. When the rotating circuit
sees low pressure it routes the pressure to the closer's release port;
high pressure switches the pressure to the clamp port. In other words,
the union is carrying both the working air pressure and the data
needed to route the pressure to the proper port.

If you're not familiar, there's some info on sequence valves he
http://beta.hydraulicspneumatics.com...educing-valves
I LOVE how you "engineers" complicate a simple solution. You need to
get Colin Chapman on board!!!!

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.

--
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 ---

On 2017-04-13, wrote:
On 13 Apr 2017 03:59:31 GMT, "DoN. Nichols"
wrote:

[ ... ]

You have my thoughts above -- including putting the solenoid
valve outside the union so it does not need to rotate. :-)

[ ... ]

Greetings DoN,
Thanks for the advice. The reason for the valve is that the rotary
union has only one air passage and I need two for the closer.

O.K. One to close it and one to open it? What happens with no
pressure -- does it default to an open or a closed position -- or
indeterminate?

The
rotary union I am using will last thousands of hours. I know this
because I have used this exact model for thousands of hours. I don't
know why it is but two passsage rotary unions that can handle the air
pressure and speed are about 10 times more expensive than single
passage ones. For liquids, like oil or coolant, two passage rotary
unions have much higher pressure and rpm limits. Anyway, the only cost
effective way to get the setup to work is to do the valving in the
spinning tube. I use DOM tubing for spindle liners and will be using
some for this project.

Can you mount two single unions on the tube? That would cost
less than a two-channel one.

I have another coil question. What if the coils
face each other rather than being concentric? Harder to wind maybe but
it might be easier to mount the stationary coil if it is facing the
moving coil.

I can't really picture what you are talking about. Perhaps you
mis-read my drawings (now snipped from above). There are two coils,
each in a cup, one rotating and one stationary facing each other. Think
of the cup as a coffee mug with a tube mounted in the bottom and
extending up to the level of the rim. The coil is wound on a form, and
then pushed into the cup and around the tube. That coil faces another
one just like it. Obviously, the coffee mugs need to be magnetically
conductive (e.g. mild steel) and with two small holes drilled in the
base of the cup -- one near the center tube, and one out near the outer
mug wall for bringing the wires through.

The center tubes in the mugs will have to be big enough to pass
your steel tube through -- and enough for perhaps 1/4" thickness of
plastic between the steel tube and the ID of the mug.

Enjoy,
DoN.

--
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 ---

On Thu, 13 Apr 2017 16:43:02 -0400, wrote:

...VERY much simpler slip rings...

Indeed! Built a crude slip ring back about 1985 that had three
channels plus ground, two of which pulsed at different rates. One
for a LED and the other for a sonalert. Very low RPM obviously, but
it worked! Used copper coated PCB board and slot car brushes. Which
were kind of hard to find in the mid 80s. Slot cars had been out of
fashion for over a decade and no internet to just 'look things up'.
http://alt-config.net/slipring.jpeg

Um, the LED was in the bats mouth;-)
--
William

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric
Slip rings with a set of alternator brushes, or heater motor brushes,
or brushes from a power tool or vacuum cleaner motor that can handle
5000RPM + are extremely simple to set up and very reliable.

On 2017-04-14, wrote:
On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

[ ... comments on using a motor as a rotary transformer snipped ... ]

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp.

I read that in another of your responses earlier today, and
posted this to which you replied yesterday, otherwise I would not hav
repeated this suggestion.

So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.

O.K. Another thought comes to mind. What happens if you use
only one port, and apply either pressure or a vacuum to it? I presume
that you need continuous pressure when it is holding, but do you need
continuous pressure to the other side to open it and hold it, or will it
open and stay pretty much open from a fairly short pulse? If a short
pulse will do, then a valve to feed the pressure to a venturi to get
vacuum will open it. You likely don't want to hold it there for long,
because a venturi is a rather inefficient way to generate a vacuum, lots
of run time on the compressor. But a short burst to open the chuck might
do well. (Check it out with short bursts for open before you mount it,
while it is easy to get to.) If this works, you can use the single
union and no need for valve control in the spindle.

The only air-operated chuck which I have seen had springs to
return to the open state, so only one pressure feed needed. This was
one made for lathe use, so it was designed for single pressure line.
Maybe there is provision inside yours for spring return, if you just
install the springs. (Sorry, that one was sold by a friend on eBay a
couple of years ago.)

Enjoy,
DoN.

--
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 ---

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

I've used a dual rotary union similar to this on a heated roller. Kind
of spendy. Deublin also makes slip rings.
http://www.deublin.com/2117-001-109/

Pete Keillor

On Thu, 13 Apr 2017 20:50:14 -0400, William Bagwell
wrote:

On Thu, 13 Apr 2017 16:43:02 -0400, wrote:

...VERY much simpler slip rings...

Indeed! Built a crude slip ring back about 1985 that had three
channels plus ground, two of which pulsed at different rates. One
for a LED and the other for a sonalert. Very low RPM obviously, but
it worked! Used copper coated PCB board and slot car brushes. Which
were kind of hard to find in the mid 80s. Slot cars had been out of
fashion for over a decade and no internet to just 'look things up'.
http://alt-config.net/slipring.jpeg

Um, the LED was in the bats mouth;-)

Hah! Well, that explains things, Mr. BSC.

--
Newman's First Law:
It is useless to put on your brakes when you're upside down.
--Paul Newman

On 14 Apr 2017 02:04:54 GMT, "DoN. Nichols"
wrote:

On 2017-04-14, wrote:
On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

[ ... comments on using a motor as a rotary transformer snipped ... ]

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp.

I read that in another of your responses earlier today, and
posted this to which you replied yesterday, otherwise I would not hav
repeated this suggestion.

So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.

O.K. Another thought comes to mind. What happens if you use
only one port, and apply either pressure or a vacuum to it? I presume
that you need continuous pressure when it is holding, but do you need
continuous pressure to the other side to open it and hold it, or will it
open and stay pretty much open from a fairly short pulse? If a short
pulse will do, then a valve to feed the pressure to a venturi to get
vacuum will open it. You likely don't want to hold it there for long,
because a venturi is a rather inefficient way to generate a vacuum, lots
of run time on the compressor. But a short burst to open the chuck might
do well. (Check it out with short bursts for open before you mount it,
while it is easy to get to.) If this works, you can use the single
union and no need for valve control in the spindle.

The only air-operated chuck which I have seen had springs to
return to the open state, so only one pressure feed needed. This was
one made for lathe use, so it was designed for single pressure line.
Maybe there is provision inside yours for spring return, if you just
install the springs. (Sorry, that one was sold by a friend on eBay a
couple of years ago.)

Enjoy,
DoN.
Greetings DoN,
Vacuum won't work because it takes too much pressure to retract. I
wish there was room for a spring return, that would really simplify
things.
Eric

On Thu, 13 Apr 2017 14:13:20 -0400, Ned Simmons
wrote:

On Thu, 13 Apr 2017 08:52:56 -0700, wrote:


Greetings DoN,
Thanks for the advice. The reason for the valve is that the rotary
union has only one air passage and I need two for the closer. The
rotary union I am using will last thousands of hours. I know this
because I have used this exact model for thousands of hours. I don't
know why it is but two passsage rotary unions that can handle the air
pressure and speed are about 10 times more expensive than single
passage ones. For liquids, like oil or coolant, two passage rotary
unions have much higher pressure and rpm limits. Anyway, the only cost
effective way to get the setup to work is to do the valving in the
spinning tube. I use DOM tubing for spindle liners and will be using
some for this project. I have another coil question. What if the coils
face each other rather than being concentric? Harder to wind maybe but
it might be easier to mount the stationary coil if it is facing the
moving coil.
Eric

I assume you need two air feeds because the closer has a double acting
cylinder. If we can also assume that the closer requires a higher
pressure for clamping than for releasing, then you may be able to use
a single passage union and a sequence valve circuit rotating with the
closer and a 2-pressure supply to the union. When the rotating circuit
sees low pressure it routes the pressure to the closer's release port;
high pressure switches the pressure to the clamp port. In other words,
the union is carrying both the working air pressure and the data
needed to route the pressure to the proper port.

If you're not familiar, there's some info on sequence valves he
http://beta.hydraulicspneumatics.com...educing-valves
Greetings Ned,
I looked at your link last night. I had never heard of sequence valves
before. I would need one that would work with only about 10 PSI
pressure difference. I'm gonna look this weekend to see what's
available.
Thanks much,
Eric

On Fri, 14 Apr 2017 06:34:20 -0500, Pete Keillor
wrote:

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

I've used a dual rotary union similar to this on a heated roller. Kind
of spendy. Deublin also makes slip rings.
http://www.deublin.com/2117-001-109/

Pete Keillor
The max speed for that rotary union is only 250 RPM. I need 4000 RPM.
The single passage ones go that fast while still being affordable. The
dual passage ones that can spin that fast and have air going through
them are about 10 times more expensive.
Eric

On Wed, 12 Apr 2017 09:11:45 -0700, wrote:

On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:

I thought about that but dismissed it because I really don't know how
I would go about doing it.

You should dismiss it because it is complication you don't need. My
contact in Ford Engineering tells me that the burst test speed for
"standard" alternators (the traditional ones before they started
designing a custom alternator for every engine) is 15,000 RPM and that
they will run up to around 10,000 RPM with the engine wound out.

So you have no problem getting the power to the solenoid. The problem
will be the solenoid itself.

The only way the solenoid could work is for the plunger to be exactly
axially aligned with the shaft. If it is off-center by even a tiny
amount, the whole assembly will be out of balance. Worse, the
centrifugal force will act to bind the plunger against the wall of the
solenoid tube.

Even if you work that out the fluid (air in this case) will be
affected by the same centrifugal force. The force will either work
against or with the valve. If it work against the valve, the valve
might not open. If it works with the valve, it might not shut.

I don't fully know what you're trying to achieve but it seems to me
that a stationary solenoid, a rotary coupling such as one of these.

https://www.mcmaster.com/#rotating-couplings/=17755fj

to get the air inside the tube. If you need to flow to be abruptly
started and stopped, my approach would be capillary tubing from the
valve to the outlet, the bore of which is chosen to provide the
desired air volume when full shop air is applied from the solenoid.
Here is an example of several bore sizes.

https://www.johnstonesupply.com/sear...pillary+tubing

If your solenoid is DC it will either require a snubber or use a
switching device capable of withstanding the flyback. A pure diode
will greatly slow the closing time because the current will continue
to flow until it is dissipated in the solenoid's resistance.

If you need it to close rapidly, the usual technique is to connect a
resistor in series with the solenoid and adjust its value until the
flyback voltage is as high as tolerable. For example if your
actuating device uses a 200 volt max rating transistor, I'll allow the
voltage to rise to no more than 100 volts.

You'll need an oscilloscope to observe this. I anticipate your not
having one but you probably have a friend that does.

If you need the valve to close very rapidly, I can describe a very
simple peak/hold circuit that supplies full voltage until the solenoid
is actuated and then drops the current to the much lower holding
value. Much less current to dissipate in the snubber.

John


So maybe you could help. Sticking out the
back of the lathe will be a steel tube. Inside this tube will be the
solenoid actuated valve and counterweights so that the tube is
balanced. And the plumbing that will bring the air from the valve to
the collet closer mounted in the spindle. Into the end of this tube
will be screwed a rotary union that passes air. If I have a coil
wrapped around the steel tube won't that be a problem? What if a
plastic sleeve were to be pressed over the O.D. of the tube and the
coil wrapped on it. Would that be better? Since I can supply any
voltage to the stationary coil it seems tome that a 1:1 ratio between
the coils would be easiest to do. Does this mean that I can also get
away with just about any number of turns provided the wire can handle
the minute current? The valve only needs .2 amps to operate so the
wire can be pretty fine. The valve operates on DC but a rectifier can
be stuffed into the tube along with everything else. Will the tube
coil need a snubber diode too? Any advice?
Thanks,
Eric
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address

On Fri, 14 Apr 2017 17:29:21 -0400, Neon John wrote:

On Wed, 12 Apr 2017 09:11:45 -0700, wrote:

On 12 Apr 2017 04:01:56 GMT, "DoN. Nichols"
wrote:

I thought about that but dismissed it because I really don't know how
I would go about doing it.

You should dismiss it because it is complication you don't need. My
contact in Ford Engineering tells me that the burst test speed for
"standard" alternators (the traditional ones before they started
designing a custom alternator for every engine) is 15,000 RPM and that
they will run up to around 10,000 RPM with the engine wound out.

So you have no problem getting the power to the solenoid. The problem
will be the solenoid itself.

The only way the solenoid could work is for the plunger to be exactly
axially aligned with the shaft. If it is off-center by even a tiny
amount, the whole assembly will be out of balance. Worse, the
centrifugal force will act to bind the plunger against the wall of the
solenoid tube.

Even if you work that out the fluid (air in this case) will be
affected by the same centrifugal force. The force will either work
against or with the valve. If it work against the valve, the valve
might not open. If it works with the valve, it might not shut.

I don't fully know what you're trying to achieve but it seems to me
that a stationary solenoid, a rotary coupling such as one of these.

https://www.mcmaster.com/#rotating-couplings/=17755fj

to get the air inside the tube. If you need to flow to be abruptly
started and stopped, my approach would be capillary tubing from the
valve to the outlet, the bore of which is chosen to provide the
desired air volume when full shop air is applied from the solenoid.
Here is an example of several bore sizes.

https://www.johnstonesupply.com/sear...pillary+tubing

If your solenoid is DC it will either require a snubber or use a
switching device capable of withstanding the flyback. A pure diode
will greatly slow the closing time because the current will continue
to flow until it is dissipated in the solenoid's resistance.

If you need it to close rapidly, the usual technique is to connect a
resistor in series with the solenoid and adjust its value until the
flyback voltage is as high as tolerable. For example if your
actuating device uses a 200 volt max rating transistor, I'll allow the
voltage to rise to no more than 100 volts.

You'll need an oscilloscope to observe this. I anticipate your not
having one but you probably have a friend that does.

If you need the valve to close very rapidly, I can describe a very
simple peak/hold circuit that supplies full voltage until the solenoid
is actuated and then drops the current to the much lower holding
value. Much less current to dissipate in the snubber.

John
SNIP
Greetings John,
I alread thought about the solenoid sticking. It will be concentric
with the lathe spindle centerline. I'm not sure but I think the valves
I have are piloted because they use so little current to change the
valve position. And it changes fast. Anyway, I already use these
valves with this closer as well as other air clamping devices. As to
the two passage rotary union you linked to if you read the specs you
will see they cannot be spun anywhere near as fast as I need to spin
it. That's why I'm going through all this falderal (izzat how it's
spelled?). As I have posted I would love a two passage rotary union
that can handle 4000 RPM and 120 PSI air. But they are about 10 times
more than the single passage types with the same air and speed rating.
Like $3000.00. I have even checked eBay. I did find a good deal on a
coolant rotary union and I bought it. But it is for coolant. And is a
single passage union. And it's going into the mill for through spindle
coolant.
Eric

Eric - perhaps just for information, you might try a side access air
coupling. This would comprise the rotating center "tube" you mention
surrounded by a metal piece with 2 "o-ring" seals for each air passage.
You could setup a test on a drill press and use the local hardware store
for "o-rings". Hopefully, the tube's diameter could be reduced.
Probably first testing would be for max pressure with no rotation then
with greater speeds. Next step would likely be searching for teflon "o-rings"
or even higher temp types.

Hul

wrote:
On Fri, 14 Apr 2017 06:34:20 -0500, Pete Keillor
wrote:

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

I've used a dual rotary union similar to this on a heated roller. Kind
of spendy. Deublin also makes slip rings.
http://www.deublin.com/2117-001-109/

Pete Keillor
The max speed for that rotary union is only 250 RPM. I need 4000 RPM.
The single passage ones go that fast while still being affordable. The
dual passage ones that can spin that fast and have air going through
them are about 10 times more expensive.
Eric

On Fri, 14 Apr 2017 22:37:18 +0000 (UTC), Hul Tytus
wrote:

Eric - perhaps just for information, you might try a side access air
coupling. This would comprise the rotating center "tube" you mention
surrounded by a metal piece with 2 "o-ring" seals for each air passage.
You could setup a test on a drill press and use the local hardware store
for "o-rings". Hopefully, the tube's diameter could be reduced.
Probably first testing would be for max pressure with no rotation then
with greater speeds. Next step would likely be searching for teflon "o-rings"
or even higher temp types.

Hul
Greetings Hul,
The rotary union I will be using is a side access one but the air
comes out the center. The problem is the high speed, 4000 RPM. O-rings
won't work in that application. It's really interesting to look online
at rotary unions. Lots of single passage 150 PSI 4000 and higher RPM
for air but not two or more. Years ago I had to design and make a
custom rotary union for a gundrill machine where I worked. It had to
seal against 2000 PSI hot oil up to about 1000 RPM. It was actually
pretty easy to do. The design was informed by the Parker Seal folks.
We were going through expensive rotary unions on this machine and my
boss wanted one that would be easy and cheap to repair. The answer was
using the correct rubber compound and letting a little oil leak past
the O-rings. The union was built with a shroud that collected the
slight leakage and drained the oil into the gundrill sump. I have
since seen this type of design on high pressure hydraulic rotating
actuators. It is apparently very common. But since I am using air
special hard seals need to be used, O-rings just won't last.
Eric

wrote:
On Fri, 14 Apr 2017 06:34:20 -0500, Pete Keillor
wrote:

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

I've used a dual rotary union similar to this on a heated roller. Kind
of spendy. Deublin also makes slip rings.
http://www.deublin.com/2117-001-109/

Pete Keillor
The max speed for that rotary union is only 250 RPM. I need 4000 RPM.
The single passage ones go that fast while still being affordable. The
dual passage ones that can spin that fast and have air going through
them are about 10 times more expensive.
Eric

On 2017-04-14, wrote:

[ ... ]

seal against 2000 PSI hot oil up to about 1000 RPM. It was actually
pretty easy to do. The design was informed by the Parker Seal folks.
We were going through expensive rotary unions on this machine and my
boss wanted one that would be easy and cheap to repair. The answer was
using the correct rubber compound and letting a little oil leak past
the O-rings. The union was built with a shroud that collected the
slight leakage and drained the oil into the gundrill sump. I have
since seen this type of design on high pressure hydraulic rotating
actuators. It is apparently very common. But since I am using air
special hard seals need to be used, O-rings just won't last.
Eric

Does it *matter* if the air union has some leaks? As long as
you can get enough pressure through. Yes, it will cost more to run the
compressor. Make it a labyrinth style for each part and try it -- first
stationary, then rotating. You can make it with two passages on the
inner part (which goes onto the tube), and two parts which bolt together
around it bolted to the frame of the lathe.

Enjoy,
DoN.

--
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 ---

On Fri, 14 Apr 2017 15:21:27 -0700, etpm wrote:
....
I already thought about the solenoid sticking. It will be concentric
with the lathe spindle centerline. I'm not sure but I think the valves
I have are piloted because they use so little current to change the
valve position. And it changes fast. Anyway, I already use these
valves with this closer as well as other air clamping devices. As to
the two passage rotary union you linked to if you read the specs you
will see they cannot be spun anywhere near as fast as I need to spin
it. That's why I'm going through all this falderal (izzat how it's
spelled?). [...]

folderol appears to be the most-common spelling, but falderal,
fol de rol, and fol-de-rol are linked as alternatives in
https://en.wiktionary.org/wiki/folderol.

https://goo.gl/RmUH86 links to a Google Ngrams chart that
compares frequencies-in-books of the four spellings.

--
jiw

Eric - do you remember what rubber compound was used on the gun drill?

Hul

wrote:
On Fri, 14 Apr 2017 22:37:18 +0000 (UTC), Hul Tytus
wrote:

Eric - perhaps just for information, you might try a side access air
coupling. This would comprise the rotating center "tube" you mention
surrounded by a metal piece with 2 "o-ring" seals for each air passage.
You could setup a test on a drill press and use the local hardware store
for "o-rings". Hopefully, the tube's diameter could be reduced.
Probably first testing would be for max pressure with no rotation then
with greater speeds. Next step would likely be searching for teflon "o-rings"
or even higher temp types.

Hul
Greetings Hul,
The rotary union I will be using is a side access one but the air
comes out the center. The problem is the high speed, 4000 RPM. O-rings
won't work in that application. It's really interesting to look online
at rotary unions. Lots of single passage 150 PSI 4000 and higher RPM
for air but not two or more. Years ago I had to design and make a
custom rotary union for a gundrill machine where I worked. It had to
seal against 2000 PSI hot oil up to about 1000 RPM. It was actually
pretty easy to do. The design was informed by the Parker Seal folks.
We were going through expensive rotary unions on this machine and my
boss wanted one that would be easy and cheap to repair. The answer was
using the correct rubber compound and letting a little oil leak past
the O-rings. The union was built with a shroud that collected the
slight leakage and drained the oil into the gundrill sump. I have
since seen this type of design on high pressure hydraulic rotating
actuators. It is apparently very common. But since I am using air
special hard seals need to be used, O-rings just won't last.
Eric

wrote:
On Fri, 14 Apr 2017 06:34:20 -0500, Pete Keillor
wrote:

On Thu, 13 Apr 2017 18:15:09 -0700, wrote:

On 13 Apr 2017 22:07:57 GMT, "DoN. Nichols"
wrote:

On 2017-04-13, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...

How well do you think an electric motor would work as a rotary
transformer? They are already balanced and built to withstand the
RPMs.

Well ... most of our electric motors are induction motors, where
the rotor is just iron and copper (or aluminum) -- no connections to it
other than magnetic coupling.

However -- a universal motor (wound rotor and commutator) could
perhaps act as a transformer -- with say AC fed into the field, and
power picked up from the commutator. But the commutator would be fixed
with relation to the field coil, so you still have the problem of
getting the power to the solenoid valve. Break out the commutator, and
pick one of the rotor windings and you have your AC (modulated by the
rotation of the rotor poles relative to the field poles), but running
those wires out to the solenoid valve would still be tricky. The wires
would interfere with mounting of the bearing at that end -- unless you
milled a couple of slots in the rotor shaft where the wires could be
passed under the bearing.

I really think that moving the solenoid valve to the outside of
the rotary coupling would make more sense as I suggested at the start of
my followup -- in spite of my having posted the design for machining
magnetic cups and coils for getting the power in through the rotating
shaft.

Enjoy,
DoN.
Of course the valve mounted outside would be better. But that won't
work because the closer is basically a double acting cylinder. This
means that it needs air pressure to clamp and remain clamped, and air
pressure to unclamp. So the rotary union would need two passages.The
way I use the closer now is with a solenoid operated valve the has one
air inlet, two outlets, and two exhausts.So when one side of the
piston is pressurized the other side is exhausted to the atmosphere.
Since air needs to be sent to both sides of a piston there needs to be
two passages in a rotary union if the valve is outside.
Eric

I've used a dual rotary union similar to this on a heated roller. Kind
of spendy. Deublin also makes slip rings.
http://www.deublin.com/2117-001-109/

Pete Keillor
The max speed for that rotary union is only 250 RPM. I need 4000 RPM.
The single passage ones go that fast while still being affordable. The
dual passage ones that can spin that fast and have air going through
them are about 10 times more expensive.
Eric

On 15 Apr 2017 03:49:46 GMT, "DoN. Nichols"
wrote:

On 2017-04-14, wrote:

[ ... ]

seal against 2000 PSI hot oil up to about 1000 RPM. It was actually
pretty easy to do. The design was informed by the Parker Seal folks.
We were going through expensive rotary unions on this machine and my
boss wanted one that would be easy and cheap to repair. The answer was
using the correct rubber compound and letting a little oil leak past
the O-rings. The union was built with a shroud that collected the
slight leakage and drained the oil into the gundrill sump. I have
since seen this type of design on high pressure hydraulic rotating
actuators. It is apparently very common. But since I am using air
special hard seals need to be used, O-rings just won't last.
Eric

Does it *matter* if the air union has some leaks? As long as
you can get enough pressure through. Yes, it will cost more to run the
compressor. Make it a labyrinth style for each part and try it -- first
stationary, then rotating. You can make it with two passages on the
inner part (which goes onto the tube), and two parts which bolt together
around it bolted to the frame of the lathe.

Enjoy,
DoN.
Greetings DoN,
I thought about labryrinth sealing but air would leak out pretty fast.
I suppose I could use the labyrinth seal for just the opening cycle so
it would be leaking for the least amount of time. If the tube mounted
solenoid valve doesn't work then maybe I'll give it a try.
Cheers,
Eric

On Sat, 15 Apr 2017 06:42:48 +0000 (UTC), Hul Tytus
wrote:

Eric - do you remember what rubber compound was used on the gun drill?

Hul
SNIP
No. It was a long time ago. The rubber was not exotic though. I just
looked for rubber compounds that could handle the temperature and oil
composition. It mighta been EPDM. I don't think it was BUNA-N.
Eric

On Sat, 15 Apr 2017 04:40:26 -0000 (UTC), James Waldby
wrote:

On Fri, 14 Apr 2017 15:21:27 -0700, etpm wrote:
...
I already thought about the solenoid sticking. It will be concentric
with the lathe spindle centerline. I'm not sure but I think the valves
I have are piloted because they use so little current to change the
valve position. And it changes fast. Anyway, I already use these
valves with this closer as well as other air clamping devices. As to
the two passage rotary union you linked to if you read the specs you
will see they cannot be spun anywhere near as fast as I need to spin
it. That's why I'm going through all this falderal (izzat how it's
spelled?). [...]

folderol appears to be the most-common spelling, but falderal,
fol de rol, and fol-de-rol are linked as alternatives in
https://en.wiktionary.org/wiki/folderol.

https://goo.gl/RmUH86 links to a Google Ngrams chart that
compares frequencies-in-books of the four spellings.
I like the most common spelling. It just looks better. But I also like
fol de rol. I can hear it being pronounced as three separate words.
Thanks,
Eric