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