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seeking slip(ring)age
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" |
seeking slip(ring)age
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. |
seeking slip(ring)age
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 $$$$. Give the small amount of power you need to transmit, I'd consider using a rotary transformer coupling to transmit the power as AC instead of DC. |
seeking slip(ring)age
Josepi wrote:
PM = permanent magnet. I guess your motives are unclear then. I understand you want to generate electrical energy form a mechanism installed on your whel chair wheels. A generator would be the only way to do this whatever the mechanism. Is my logic too far off? ----------------- Yes , he wants to supply power two strings of LEDs that he has mounted on his wheels . Though I don't understand why he wants two separate power feeds, unless he has them strobing or flashing independently of each other . Hactar , you're on the right track with the CD/plastic disc idea . I suggest the static component could be something similar to the power pickup brushes used on slot cars . Simple and robust , with mimimal protrusion that can be damaged when the wheels are off the chair . -- Snag Learning keeps you young ! |
seeking slip(ring)age
In article . com,
Pete C. wrote: Hactar wrote: I was told this might be a good place to ask. I'm looking for a slipring or commutator to go around the axle to my wheelchair wheels. .... Does such a thing exist for a reasonable amount of money, perhaps in the model-making or robotics communities? I have an idea about making one (per side) out of a CD-R, some alternator brushes, and some sheet metal, if a pre-made one can't be found. I figure I'll put the CD part on the wheel, to keep its angular momentum down. I'm afraid you won't find much for off the shelf slip ring assemblies, and what there are will be $$$$. 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_ |
seeking slip(ring)age
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 |
seeking slip(ring)age
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. |
seeking slip(ring)age
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 $$$$. Give the small amount of power you need to transmit, I'd consider using a rotary transformer coupling to transmit the power as AC instead of DC. What's a rotary transformer? I really need to minimize the "on wheel" weight; it's especially important not to cause a torque in the wheel. Basically just two coils of magnet wire, concentric with the rotary axis, one mounted on the rotating part (wheel) and one on the fixed part (chair/axle), AC voltage applied to one is coupled to the other with the rotation of the moving part having essentially no effect on the coupling. Also has the advantage of being non-contact and non-wear. |
seeking slip(ring)age
Hactar wrote: In article . com, Pete C. wrote: Hactar wrote: I was told this might be a good place to ask. I'm looking for a slipring or commutator to go around the axle to my wheelchair wheels. ... Does such a thing exist for a reasonable amount of money, perhaps in the model-making or robotics communities? I have an idea about making one (per side) out of a CD-R, some alternator brushes, and some sheet metal, if a pre-made one can't be found. I figure I'll put the CD part on the wheel, to keep its angular momentum down. I'm afraid you won't find much for off the shelf slip ring assemblies, and what there are will be $$$$. 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. |
seeking slip(ring)age
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 ! |
seeking slip(ring)age
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. |
seeking slip(ring)age
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 |
seeking slip(ring)age
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 |
seeking slip(ring)age
"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. |
seeking slip(ring)age
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. |
seeking slip(ring)age
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 |
seeking slip(ring)age
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) |
seeking slip(ring)age
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 |
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