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Post by Ron Walker on Nov 26, 2022 16:05:59 GMT -7
Posted by: Ron Walker Nov 4 2007, 02:19 PM QUOTE(mrgare5050 @ Nov 3 2007, 02:18 AM) * ok 1 ring per circuit, but what slips? why dont the contacts just go round and round like a clock? Here is an example of "stacked" slip rings. This is the central core of the Goto E-5. You can see the 8 slip rings and the brush stack to the left. You can see that the "stacked" slip rings fit within the central core with a large ball bearing on top and bottom. The brush stack bolts to the fixed central core shell and slides along each ring. In the planet cage of this same projector are examples of the flat slip rings virtually identical to the type I made. They are placed under the gears that drive the planet projectors. Note that there are only two slip rings (positive and ground) as there is only one bulb for each projector.
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Post by Ron Walker on Nov 26, 2022 16:07:52 GMT -7
Posted by: Ron Walker Nov 4 2007, 02:38 PM QUOTE(Ken Miller @ Nov 2 2007, 07:43 AM) * For my slip rings I used sections of brass pipe. I made plungers from brass rod to act as the "brushes". The plungers are pushed down by hardware springs and then a threaded brass rod pushes down on the spring to adjust tension and provide a point for the electrical connection. I can post drawings if anybody has any interest.
Motor brushes are a good idea. They are designed for a sliding contact, and wouldn't wear or cause as much friction as my brass plungers. I just figured there wouldn't be nearly as much rotation of my starball as there would be for a motor rotor.
Love to see drawings. Pictures would be even better!
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Post by Ron Walker on Nov 26, 2022 16:08:13 GMT -7
Posted by: Ron Walker Nov 4 2007, 02:50 PM QUOTE(charles jones @ Nov 1 2007, 01:42 AM) * Hi Ron
Fantastic! This was my idea too except that I thought it might need thicker material and was planning to buy copper sheet and glue it to a plate, then cut the rings on a lathe as you have done.
Of course, I haven't been able to do anything while I am here.
When I get home, the first thing is I have ordered a small lathe to begin making parts.
Charles
You really don't need thicker material. You would be surprised how much power a 1/4 inch wide strip of printed circuit can handle. Basically it depends on the number of brushes that are in contact with the ring that really determines how much power can flow. One contact should easily carry five amps or more.
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Post by Ron Walker on Nov 26, 2022 16:08:34 GMT -7
Posted by: Ron Walker Nov 4 2007, 02:54 PM QUOTE(charles jones @ Nov 1 2007, 06:35 PM) * Ron
Do you have a source for the blank PC boards?
I think you mentioned earlier using brushes from an electric drill. Have you tried this or just in theory? Any suggestions for mounting, etc., if you have exiperimented with it? On a side note: I will be meeting someone at the Adelaide Planetarium on Monday. They have the small Zeiss without planetary motion, and the spherical mirror projection. Then on the following Saturday, I am meeting Paul Bourke in Perth, the inventor of the spherical mirror projector. I'll report back on both visits within a week.
Charles
When you meet with Paul, invite him over to our forum. It would be good to get his point of view on the video/mirror system, since he is the inventor of it. I know I would like to learn more.
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Post by Ron Walker on Nov 26, 2022 16:09:10 GMT -7
Posted by: charles jones Nov 5 2007, 06:40 AM Many thanks for the photos of the slip rings in the Goto!!!
Interesting to see how these compare with the photos on the net from commercial companies that manufacture these. I know I'll be able to make them, but it is an extra chore isn't it. The truth is there seems to be nothing out there that will exactly work in the space and configuration that I will need.
A report soon on the Adelaide planetarium -- a small Zeiss.
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Post by Ron Walker on Nov 26, 2022 16:15:02 GMT -7
Posted by: Ken Miller Nov 25 2007, 09:09 PM Here is some info on my slip ring efforts. This is the setup on my Spitz A3 starglobe: What you are looking at is the axle and bearing supporting the globe. The wheel on the right is my grip for manually rotating the globe. The bearing is the two white blocks of high density polyethlyene (HDP, cutting board material)). The axle is brass pipe with an insulated fitting between the two bearings (hidden inside the wooden spacer that the blocks are mounted to). The plungers that make contact with the brass pipe are fitted into holes drilled into each of the two pieces of HDP, threaded for 1/4 - 20 threaded rod (the wires connect to the toip ends of the threaded rods). What is inside those holes is illustrated in the following message.
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Post by Ron Walker on Nov 26, 2022 16:16:48 GMT -7
Posted by: Ken Miller Nov 25 2007, 09:19 PM The piston assembly: The brass slug that makes contact with the pipe is shown on the left. It is smaller than 1/4 inch diameter so that it slips easily inside the 1/4 - 20 threaded hole. The spring is between the threaded rod and the brass slug to maintain tension. The external electrical connection is to the end of the threaded rod (the wire is shown connected to the end of the threaded rod to help illustrate how it goes together). The slug is dropped into the hole, followed by the spring, and then the threaded rod is screwed down into the hole until the spring is compressed, then the the rod is locked in place with a 1/4 - 20 nut, and the wire is fastened to the dnd of the threaded rod.
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Post by Ron Walker on Nov 26, 2022 16:20:30 GMT -7
Posted by: Ken Miller Nov 25 2007, 09:24 PM Here are the slip rings on the Viewlex Apollo projector: The outside slip ring is ground (electrical return circuit), the next ring is for the coordinate projector, then comes the Sun/Moon projector ring, and finally the starlamp/Milky Way projector ring. (Added by Ron 11-26-22) Surprising how the commercial slipring looks like my experimental one.
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Post by Ron Walker on Nov 26, 2022 16:21:21 GMT -7
Posted by: charles jones Jan 13 2008, 10:31 PM Slip rings again!!!
I finally will be starting to actually build my projector the week after next. I'll take photos as work progresses and furnish them later. The first order of events, besides ordering parts, I've decided will be making the SLIP RINGS. Their size will make the difference of the dimensions of the central core, etc.
The PC borad is a great idea! But, Ron, have you solved the brush problem? I've purchased some med-sized relays, taken them apart. But the contacts seem to be a bit abrasive. I did discover the perfect item: A brush assembly off of a small variac. It is perfect. However, I am going to need about 16 slip rings, with two brushes each. 32 variacs would cost a fortunate unless I find some surplus outlet that has only the brushes seperately.
The brushes from an electric drill seem to be too large and have springs attached that would take up too much room.
What do you think of a simple spring brass strip with no brush at all? What did you come up with, Ron?
Also, (can't find the post) Ron were you the one who had extra timing belts you couldn't use?
Charles
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Post by Ron Walker on Nov 26, 2022 16:37:33 GMT -7
Posted by: Ron Walker Jan 14 2008, 11:02 AM QUOTE(charles jones @ Jan 13 2008, 10:31 PM) * Slip rings again!!!
I finally will be starting to actually build my projector the week after next. I'll take photos as work progresses and furnish them later. The first order of events, besides ordering parts, I've decided will be making the SLIP RINGS. Their size will make the difference of the dimensions of the central core, etc.
The PC borad is a great idea! But, Ron, have you solved the brush problem? I've purchased some med-sized relays, taken them apart. But the contacts seem to be a bit abrasive. I did discover the perfect item: A brush assembly off of a small variac. It is perfect. However, I am going to need about 16 slip rings, with two brushes each. 32 variacs would cost a fortunate unless I find some surplus outlet that has only the brushes seperately.
The brushes from an electric drill seem to be too large and have springs attached that would take up too much room.
What do you think of a simple spring brass strip with no brush at all? What did you come up with, Ron?
Also, (can't find the post) Ron were you the one who had extra timing belts you couldn't use?
Charles
I don't have any extra timing belts, yet. The Goto E-5 just uses simple brass strips and works fine. I'm spending most of my time working on the various drives of the A3P right now. Time is tight.
(Added 11-26-22) I think a simple copper or brass strip like markspoelstra used on his 3D models might work fine. Not sure if thinner or thicker plate would be best as the material would need to use its natural elasticity to hold pressure on the rings themselves.
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Post by Ron Walker on Nov 26, 2022 16:38:07 GMT -7
Posted by: Ken Miller Jan 14 2008, 11:52 AM QUOTE(charles jones @ Jan 13 2008, 09:31 PM) * The PC borad is a great idea! But, Ron, have you solved the brush problem? I've purchased some med-sized relays, taken them apart. But the contacts seem to be a bit abrasive. I did discover the perfect item: A brush assembly off of a small variac. It is perfect. However, I am going to need about 16 slip rings, with two brushes each. 32 variacs would cost a fortunate unless I find some surplus outlet that has only the brushes seperately.The variac wiper elements are available as replacement parts, unfortunately they're like $20 each.
I'm not sure how abrasive relay contacts should be, but they weren't designed for a sliding-type contact. That's not to say that it wouldn't work. I would think it would be worth a try; its not like it would have heavy use in the long run. You would probably find various kinds of plating on relay contacts -- some prone to wear and some not.
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Post by Ron Walker on Nov 26, 2022 16:38:45 GMT -7
Posted by: charles jones Jan 15 2008, 04:32 PM QUOTE(Ron Walker @ Jan 14 2008, 10:02 AM) * The Goto E-5 just uses simple brass strips and works fine. I'm spending most of my time working on the various drives of the A3P right now.
I understand. Thanks for the info on the GOTO. It looked like brass strips in the photo.
I am anxious to hear (and see) what size motor, pulleys and timing belts you end up using for the A3P. I'll be into this in about a month I believe.
Charles
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Post by scotttucker on Nov 27, 2022 1:43:15 GMT -7
Thank you for continuing to re-post these threads Ron. One of the brightest silver linings of the demise of the old OC is that stuff that I missed first time round is given an airing - this is great stuff.
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Post by Ron Walker on Nov 27, 2022 12:26:02 GMT -7
I too had forgotten how much stuff and good information had accumulated over the last fifteen years.
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