I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. Four conductors would be nice,
but I can live with two. Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

--
-eben P royalty.mine.nu:81
If you need someone to blame
Throw a rock in the air
You'll hit someone guilty -- U2, _Zooropa_, "Dirty Day"

PM = permanent magnet.

I guess your motives are unclear then. I understand you want to generate
electrical energy form a mechanism installed on your whel chair wheels. A
generator would be the only way to do this whatever the mechanism.

Is my logic too far off?

-----------------

"Hactar" wrote in message ...
PM? That sounds like a moving-magnet generator to me, which might have
problems if I stop, which I might do for an hour or two.

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. Four conductors would be nice,
but I can live with two. Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

In article ,
Josepi After a 1 year Usenet restriction resulting from a criminal charge a troll, blaming me attempts to incite group harrassment Spends $100s monthly on accounts just to troll wrote:
"Hactar" wrote in message ...

PM? That sounds like a moving-magnet generator to me, which might have
problems if I stop, which I might do for an hour or two.

PM = permanent magnet.

I guess your motives are unclear then. I understand you want to generate
electrical energy form a mechanism installed on your whel chair wheels. A
generator would be the only way to do this whatever the mechanism.

Is my logic too far off?

Indeed, sorry if I was unclear. A generator would make it too hard to
push (OK, harder than it is now), and wouldn't work at all without
constant energy input. Right now each string is independently powered
and switched, by a wheel-mounted battery pack. I aim to have one
centralized battery (+ voltage conversion if necessary) and one switch.
That's where the slipring comes in.

--
-eben P http://royalty.mine.nu:81

Every normal man must be tempted at times to spit upon his hands,
hoist the black flag, and begin slitting throats. -- H.L. Mencken

Josepi wrote:
PM = permanent magnet.

I guess your motives are unclear then. I understand you want to
generate electrical energy form a mechanism installed on your whel
chair wheels. A generator would be the only way to do this whatever
the mechanism.
Is my logic too far off?

-----------------
Yes , he wants to supply power two strings of LEDs that he has mounted on
his wheels . Though I don't understand why he wants two separate power
feeds, unless he has them strobing or flashing independently of each other .
Hactar , you're on the right track with the CD/plastic disc idea . I
suggest the static component could be something similar to the power pickup
brushes used on slot cars . Simple and robust , with mimimal protrusion that
can be damaged when the wheels are off the chair .

--
Snag
Learning keeps
you young !

In article . com,
Pete C. wrote:

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels.
....
Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

What's a rotary transformer? I really need to minimize the "on wheel"
weight; it's especially important not to cause a torque in the wheel.

--
-eben P http://royalty.mine.nu:81
SAGITTARIUS: All your friends are laughing behind your back... kill
them. Take down all those naked pictures of Ernest Borgnine you've
got hanging in your den. -- Weird Al, _Your Horoscope for Today_

On 5/5/2011 11:30 AM, Hactar wrote:
The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially.

The most common slipring assembly is the slipring on the steering column
of an auto for the horn. Perhaps two different size diameters can be found.

Kevin Gallimore

axolotl wrote:

On 5/5/2011 11:30 AM, Hactar wrote:
The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially.

The most common slipring assembly is the slipring on the steering column
of an auto for the horn. Perhaps two different size diameters can be found.

Kevin Gallimore

They use clocksprings these days, not continuous rotation compatible.

Hactar wrote:

In article . com,
Pete C. wrote:

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels.
...
Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

What's a rotary transformer? I really need to minimize the "on wheel"
weight; it's especially important not to cause a torque in the wheel.

Basically just two coils of magnet wire, concentric with the rotary
axis, one mounted on the rotating part (wheel) and one on the fixed part
(chair/axle), AC voltage applied to one is coupled to the other with the
rotation of the moving part having essentially no effect on the
coupling. Also has the advantage of being non-contact and non-wear.

Hactar wrote:

In article . com,
Pete C. wrote:

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels.
...
Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

What's a rotary transformer? I really need to minimize the "on wheel"
weight; it's especially important not to cause a torque in the wheel.


They were used in VCRs to transfer the RF between the rotating heads
and the electronics.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

axolotl wrote:
On 5/5/2011 11:30 AM, Hactar wrote:
The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed
(that's easy, just push a button) and the body's put in a car trunk,
and it only has about 10mm clearance axially.

The most common slipring assembly is the slipring on the steering
column of an auto for the horn. Perhaps two different size diameters
can be found.
Kevin Gallimore

Seems to me everybody is making this way more difficult than it needs to
be . A plastic disc with two rings of thin brass glued to it , holes thru to
solder a wire to the back side of the rings . Mount 'em on the wheel , use a
pair of slot car type brushes mounted to the frame of the chair to feed the
power to the rings . Done deal , and if he wants 4 rings instead of two ,
that just ain't that much harder.
Fer cryin' out loud , I could whip this up outta scraps I have layin'
around in an afternoon !!
--
Snag
Learning keeps
you young !

In article . com,
Pete C. wrote:

Hactar wrote:

In article . com,
Pete C. wrote:

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels.
...
Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

What's a rotary transformer? I really need to minimize the "on wheel"
weight; it's especially important not to cause a torque in the wheel.

Basically just two coils of magnet wire, concentric with the rotary
axis, one mounted on the rotating part (wheel) and one on the fixed part
(chair/axle), AC voltage applied to one is coupled to the other with the
rotation of the moving part having essentially no effect on the
coupling. Also has the advantage of being non-contact and non-wear.

That sounds like it would work, if it were thin enough. I'd need a
rectifier/capacitor and voltage converter on each wheel, and an inverter
on the body. Where do I find one, or is it something I make?

--
-eben P royalty.mine.nu:81

Q: What kind of modem did Jimi Hendrix use?
A: A purple Hayes.

In article ,
"Snag" wrote:

Seems to me everybody is making this way more difficult than it needs to
be . A plastic disc with two rings of thin brass glued to it , holes thru to
solder a wire to the back side of the rings . Mount 'em on the wheel , use a
pair of slot car type brushes mounted to the frame of the chair to feed the
power to the rings . Done deal , and if he wants 4 rings instead of two ,
that just ain't that much harder.
Fer cryin' out loud , I could whip this up outta scraps I have layin'
around in an afternoon !!

Printed circuit board material might be a better approach to the plastic
and metal - it's already well-glued.

Something like bullet catches (spring-loaded metallic, robust) might
make a less fiddly connection than the slot car type springs (are we all
revealing our age by even knowing what those are, or are they still
around these days?) Probably want a capacitor on (in) each wheel to make
up for momentary glitches owing to lack of perfection. Also want
something to cut the contacts off from power before it's taken apart and
loaded in a car trunk. Carbon brushes would work better when assembled,
but are not very rugged apart.

--
Cats, coffee, chocolate...vices to live by

Hactar expressed precisely :
I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. Four conductors would be nice,
but I can live with two. Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

Many childrens scooters come with flashing lights in the small wheels.

http://shop.kmart.com.au/wcsstore/Km...40935607-f.jpg
The lights are only on when the scooter is moving.
I have no idea how they work but I would be looking for some clues
there.
At 77 I have no use for scooters but I am always on the lookout for odd
ways of doing things as I build helpful devices dor disabled people of
all ages.

--
John G

"John G" wrote in message
. au...
Hactar expressed precisely :
I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. Four conductors would be nice,
but I can live with two. Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

Many childrens scooters come with flashing lights in the small wheels.

http://shop.kmart.com.au/wcsstore/Km...40935607-f.jpg
The lights are only on when the scooter is moving.
I have no idea how they work but I would be looking for some clues there.
At 77 I have no use for scooters but I am always on the lookout for odd
ways of doing things as I build helpful devices dor disabled people of all
ages.

--
John G



Some of those things (in wheels, shoes, bouncy balls) use a light spring
where vibration or centrifugal force causes it to contact a terminal wire
etc etc.

Hactar wrote:

In article . com,
Pete C. wrote:

Hactar wrote:

In article . com,
Pete C. wrote:

Hactar wrote:

I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels.
...
Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

I'm afraid you won't find much for off the shelf slip ring assemblies,
and what there are will be $$$$. Give the small amount of power you need
to transmit, I'd consider using a rotary transformer coupling to
transmit the power as AC instead of DC.

What's a rotary transformer? I really need to minimize the "on wheel"
weight; it's especially important not to cause a torque in the wheel.

Basically just two coils of magnet wire, concentric with the rotary
axis, one mounted on the rotating part (wheel) and one on the fixed part
(chair/axle), AC voltage applied to one is coupled to the other with the
rotation of the moving part having essentially no effect on the
coupling. Also has the advantage of being non-contact and non-wear.

That sounds like it would work, if it were thin enough. I'd need a
rectifier/capacitor and voltage converter on each wheel, and an inverter
on the body. Where do I find one, or is it something I make?

You'd have to build it. Also, you wouldn't be running 120V 60Hz AC to
it, you'd be using something like 12V AC and probably a few KHz
frequency. This is similar to the setup used for waterproof non contact
charging stations as seen on some electric shavers.

On May 5, 9:57*pm, (Hactar) wrote:
...
Could you just put flashing lights on the frame in line with
reflectors on the spokes?

jsw

In article ,
Jim Wilkins wrote:
On May 5, 9:57 pm, (Hactar) wrote:
...
Could you just put flashing lights on the frame in line with
reflectors on the spokes?

This is the look I'm going for:

http://royalty.mine.nu:81/decorations-2010.jpg

--
You can't get a leopard to change his spots... You can explain it care-
fully to the leopard, but it will just sit there lookng at you, knowing
that you are made of meat. After a while it will perhaps kill you.
Geoffrey Pullum, Language Log (2007-01-04)

On May 5, 8:30*am, (Hactar) wrote:
I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. *The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. *On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. *Four conductors would be nice,
but I can live with two. *Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. *I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

--
-eben * * * * *royalty.mine.nu:81
* * *If you need someone to blame
* * *Throw a rock in the air
* * *You'll hit someone guilty -- U2, _Zooropa_, "Dirty Day"

On May 5, 8:30*am, (Hactar) wrote:
I was told this might be a good place to ask.

I'm looking for a slipring or commutator to go around the axle to my
wheelchair wheels. *The catches are, it needs a 1" center hole (to go
around the axle nut), nothing can break if the wheel's removed (that's
easy, just push a button) and the body's put in a car trunk, and it only
has about 10mm clearance axially. *On the plus side, it only needs to
carry a hundred mA, its radial clearance is something close to two feet,
and my maximum speed is around 75 RPM. *Four conductors would be nice,
but I can live with two. *Does such a thing exist for a reasonable amount
of money, perhaps in the model-making or robotics communities?

I have an idea about making one (per side) out of a CD-R, some
alternator brushes, and some sheet metal, if a pre-made one can't be
found. *I figure I'll put the CD part on the wheel, to keep its angular
momentum down.

--
-eben * * * * *royalty.mine.nu:81
* * *If you need someone to blame
* * *Throw a rock in the air
* * *You'll hit someone guilty -- U2, _Zooropa_, "Dirty Day"

If you have pneumatic tires and you can dismount the rims from the
spokes you can make up little insulators to fit around the spokes to
electrically isolate the rim from the spokes. Now all you would have
to do is make a spring loaded brush to contact the rim and one to make
contact with the hub and then you would be in business. (Just stay out
of deep puddles of salt water) one side of the lighting could then be
attached to any spoke, and you could tun a thin strip of copper
through the valve stem hole and make that your second connection.

I think if you went this way it would be best to do one spoke at a
time and that way your wheel would not get too far out of whack as you
can re-tighten one at a time. Alternatively you could just take a
spare set of rims to a bike shop and let the wizards do it and true
the wheels. (Probably better than they come from the factory.)

Of course if the rims are anodized aluminum that might not conduct
very well and you would have to get below the anodizing for it to
work.

How much space is there between the spokes at the hub? If you had
enough room you could slip a soft battery case using either AA or C
cells that were sewn into a strap that could be fastened around the
inside hub with Velcro. Out of this a small switch, plug for the
lights and and a charging jack would come out to hook everything up.
You might also build in the switch that could detect motion and if
static for more than a minute or horizontal it would shut off. Or you
could mount the batteries parallel with the spokes fastened between
plastic disks. What I am thinking about here is two flexible plastic
disks 6 to 10 inches in diameter. Each disk would have a hole in it
the same size as the wheel hub and a slit from the hole to the outside
edge. The batteries could be attached with zip ties through slits in
the plastic and then you could feed one side of the slit in between
the spokes and wind it around so that it would be between the spokes.
A couple more zip ties to fasten this assembly to the spokes and you
are in business.

I like the plastic disk idea the best as it would be cheap and easy to
make. You might skip the switch altogether and just use a plug that
you could either plug your lights into or unplug the lights to shut it
off or to plug in the charger.

Good luck with the project.

Roger Shoaf