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Post by Ron Walker on Aug 24, 2022 11:51:34 GMT -7
Posted by: Ron Walker Jan 17 2008, 12:13 PM QUOTE(mrgare5050 @ Jan 17 2008, 11:52 AM) * why 40? a rather biblical number
Actually there were two reasons. One it needed to be smaller in circumference so as not to block the adjustment shaft which continues out to the back of the motor core, and secondly I wanted the largest circumference as possible so the the torque (strain) on all of the components would be as low as possible but still not cause a problem with "one". Also you can add in the cost per gear vs. teeth and what is a standard size gear.
I never made the cosmic connection but who knows.....it's probably the number of years it will take me to get this all up and running!
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Post by Ron Walker on Aug 24, 2022 11:52:20 GMT -7
Posted by: Ron Walker Jan 17 2008, 12:21 PM QUOTE(mrgare5050 @ Jan 17 2008, 09:23 AM) * planetarium people love 'arcane' machinery do they not?
you can buy almost ANYTHING and turn it into planetarium equipment.
It's really kind of funny how I find myself looking at things at every store I go to, no matter why I went in the first place, and wind up wondering if I could use it in any of my planetarium endeavors.
You were actually the first to mention this mental condition so it could possible be called "Gareidious", or "hpad".
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Post by Ron Walker on Aug 24, 2022 11:52:47 GMT -7
Posted by: mrgare5050 Jan 17 2008, 12:38 PM you know, you could make a star cylinder out of an old water heater. im not saying I WILL .. but.. YOU COULD ....
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Post by Ron Walker on Aug 24, 2022 11:53:30 GMT -7
Posted by: charles jones Jan 18 2008, 02:04 AM Ron, you're doing a fantastic job! Thanks for all the documentation as this will help me a lot. I had decided I wanted to do a similiar thing on my "built from scratch" projector mainly because I thought I'd save space by not having the secondary gear box and the synchronous motor below the main analog.
But it does appear that the timing belt pulleys take up more space than I thought. Would you say it is less than the original?
Also, did you find you did not need idler pulleys?
I like the idea of taking all the energy from the moon projector and driving it with the single motor.
Have you found a suitable motor for this yet? I will be curious to see what you find. So far, I've looked at DC motors that I think are larger than needed.
Charles
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Post by Ron Walker on Aug 24, 2022 11:54:01 GMT -7
Posted by: Ron Walker Jan 18 2008, 10:57 AM QUOTE(charles jones @ Jan 18 2008, 02:04 AM) * Ron, you're doing a fantastic job! Thanks for all the documentation as this will help me a lot. I had decided I wanted to do a similiar thing on my "built from scratch" projector mainly because I thought I'd save space by not having the secondary gear box and the synchronous motor below the main analog.
But it does appear that the timing belt pulleys take up more space than I thought. Would you say it is less than the original?
Also, did you find you did not need idler pulleys?
I like the idea of taking all the energy from the moon projector and driving it with the single motor.
Have you found a suitable motor for this yet? I will be curious to see what you find. So far, I've looked at DC motors that I think are larger than needed.
Charles
Thanks Charles.
The timing belts take up about half the space of the original motor system. If you look at one of your analogs you will note that there is a small platform approximately two inches from the analog main plate that supports the motor which extends another two inches beyond that.
Mercury and the Sun obviously stick out further then the other analogs but they are still about a full inch shorter then the original platform and motor combination. In the adaptors I made to increase the shaft diameter to 1/4 inch I installed set screws about 1/4 of an inch up the shaft. They are longer then they need to be and stick out, not allowing the gear to sit down as far as it could. Finding or machining very short set screws which would fit below the shaft diameter would allow an even tighter thinner system. This really didn't matter to me, as I have the entire original motor core area to work with.
I will be adding idler pulleys for each belt just to get rid of the extra slack. Because of the critical alignment of the mirrors and projectors, I didn't want to move the position of the actual analogs (this is a problem you don't have). It is surprising how just adding one tooth to a belt (a pitch of 0.08 inch) makes a big difference in how tight a belt works. Another problem is working with the available stock sizes. Unfortunately they stock a belt one tooth shorter and one tooth longer then I really need. I tried the one shorter and I could see the drive shafts bend ever so slightly so I went with the one tooth larger. Because 180 degrees of the gear is engaged there is no slippage, however, there is a time lag when direction is reversed as the belt tension shifts from one side of the belt to the other. I'm going to add idlers just to take up this extra "play" in the system. I may however just use a small rotating slip bearing on the outside of the belt. This is my next experiment. I do, however want to add one more gear (which will act as an idler) but will be used to drive a small selsyn motor that will power a day/month/year indicator back at the control board. I may take the drive here at a year per revolution or (for better torque) at the actual drive motor which will rotate at least once per month.
I've not yet looked into drive motors as I am not sure of what the torque needed will be. I know that I will need at least one flexible shaft to power the Moon phasing gearing and have not yet decided about the image correcting dove prism. It might be just another timing belt.
The Moon drive requires a reversing gear to keep the image moving in the proper direction. One was provided on the double motor system behind the Moon analog. This is required because the original drive motor revolves twelve times a year and the Moon does not. There is a reduction gear directly on the back of the analog at the center drive shaft which corrects for this. The correcting gear reverses the rotation direction. In the original design this didn't matter because they just reversed power to the windings and ran the motor in the opposite direction. They added a second motor for extra torque and connected them with a simple one to one gear system. Reversing that motor to the first allowed for harmonious operation. Since a timing belt does not reverse rotation, this gearing is required. It is possible that there might be a timing gear combination that would allow driving the Moon directly, but I never looked into it as it would require extra gearing elsewhere on the Moon projector. Now I'm thinking it would be worth the experiment so I will count the teeth on the analog gears and see if the system can be made simpler. All of this gearing is only used to drive the Moon analog only and thus requires very little torque.
Picking a motor requires deciding what speed I would like the the entire annual motion to provide. Probably the fastest would be a year in one minute which would require a 12 rpm motor. Since the Moon is the "fastest" object in the sky, what I would want it to do probably is the deciding factor for slowest speed. I can't imagine ever needing the Moon to move slower then one minute per lunar month which would mean a 1 rpm motor.
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Post by Ron Walker on Aug 24, 2022 11:56:16 GMT -7
Posted by: charles jones Jan 18 2008, 03:26 PM QUOTE(Ron Walker @ Jan 18 2008, 09:57 AM) * In the original design this didn't matter because they just reversed power to the windings and ran the motor in the opposite direction.
So inotherwords, when the rest of the motors ran clockwise, the moon motor ran ccw? What about the phases and dove prism?
I still don't quite follow why the moon motor needs to run opposite; when I get into it and a closer look at the analog I guess I'll see. But I'm glad you pointed this out.
Regarding motors and motor drives, I called Minarik. (www.minarik.com & http://www.minarikdrives.com) They actually started as a little company in downtown Los Angeles. As teenager, my father took me there to buy small motors for my first planetarium. Bill (I think that was his first name) Minarik, owner, took me aside and worked with me for an hour to figure out what I needed. Now it's become a huge corporate, world wide. Guess what. The service is still the same today. I called the corporate office and they immediately connected me to an engineer who spent a 1/2 hr on the phone going various motors, gearing, how I'd have to wire the drive to make it go forward or reverse, etc. It was great!
While Minarik on line "catalog" is a bit sketchy on the data of the motor, the engineer took me to Bodine (on line) where schematics and all data is displayed. The three brands of DC motors they carry are Bodine, Leeson and Bison. (www.bisongearing.com)
I've selected my motors for Latitude and Daily motion, but not a motor for the analogs yet.
I did learn that most of the drives allow the motor to go in only one direction. But by wiring a 3 position switch (on-off-on), you can, in a sense, reverse the wiring so the motor will run in the other direction.
I also learned there is a special drive controller that works this way: With the position of center on the potentiameter, the motor stops; turn it CW and the motor speed increases; turn it back (CCW) the speed slows down, stops at the center point, and then begins to increase in the opposite direction as you continue to rotate the knob CCW.
Sound pretty cool! But you guessed it, this controller is very expensive. So I am opting to use the cheaper ones and wire the switch in.
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Post by Ron Walker on Aug 24, 2022 11:56:36 GMT -7
Posted by: charles jones Jan 18 2008, 03:31 PM Ron,
By the way, where did you get the pulleys? Surplus or new?
A very clever idea for an inexpensive bearing!
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Post by Ron Walker on Aug 24, 2022 11:57:07 GMT -7
Posted by: Ron Walker Jan 19 2008, 10:31 AM QUOTE(charles jones @ Jan 18 2008, 03:31 PM) * Ron, By the way, where did you get the pulleys? Surplus or new? A very clever idea for an inexpensive bearing! I got them surplus from: www.candhsales.biz/cgi-bin/shop991/shop.pl/SID=378259849/page=MOUS.htm#BR9856A description and part number: BAKELITE PULLEY WITH BEARING QTY 10 LACANNE, #50-N. Similar to BR2051. Bakelite plastic pulley which has a ball bearing mounted in the center hub. The bearing is an ADR-JN6C. The bearing bore is 15/64" nom. The pulley has a 2-9/32" outside dia and a thickness of 5/16" max. The outside edge of th epulley has a 3/32" nom wide round-bottom groove. This groove is approx 5/32" deep. QTY 10 Stock #BR2052X10 QTY 10 $25.00 Others have said that C & H went out of business but I just got this off the web. Perhaps it was just their retail store. I would hate to see them go as they are a treasure trove for the experimenter.
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Post by Ron Walker on Aug 24, 2022 11:57:40 GMT -7
Posted by: Ron Walker Jan 19 2008, 11:09 AM QUOTE(charles jones @ Jan 18 2008, 03:26 PM) * So inotherwords, when the rest of the motors ran clockwise, the moon motor ran ccw? What about the phases and dove prism?
I still don't quite follow why the moon motor needs to run opposite; when I get into it and a closer look at the analog I guess I'll see. But I'm glad you pointed this out.
Regarding motors and motor drives, I called Minarik. (www.minarik.com & http://www.minarikdrives.com) They actually started as a little company in downtown Los Angeles. As teenager, my father took me there to buy small motors for my first planetarium. Bill (I think that was his first name) Minarik, owner, took me aside and worked with me for an hour to figure out what I needed. Now it's become a huge corporate, world wide. Guess what. The service is still the same today. I called the corporate office and they immediately connected me to an engineer who spent a 1/2 hr on the phone going various motors, gearing, how I'd have to wire the drive to make it go forward or reverse, etc. It was great!
While Minarik on line "catalog" is a bit sketchy on the data of the motor, the engineer took me to Bodine (on line) where schematics and all data is displayed. The three brands of DC motors they carry are Bodine, Leeson and Bison. (www.bisongearing.com)
I've selected my motors for Latitude and Daily motion, but not a motor for the analogs yet.
I did learn that most of the drives allow the motor to go in only one direction. But by wiring a 3 position switch (on-off-on), you can, in a sense, reverse the wiring so the motor will run in the other direction.
I also learned there is a special drive controller that works this way: With the position of center on the potentiameter, the motor stops; turn it CW and the motor speed increases; turn it back (CCW) the speed slows down, stops at the center point, and then begins to increase in the opposite direction as you continue to rotate the knob CCW.
Sound pretty cool! But you guessed it, this controller is very expensive. So I am opting to use the cheaper ones and wire the switch in.
I have not tackled the other two drives as yet so I'm not sure of the direction of rotation. I will do that as soon as I've got the central core finished.
The Moon motor runs in the opposite direction because it was the simplest solution for the original drive. All of the other analogs derive their motion from a drive representing one year of Earth motion. Since every planet analog requires this speed for the Earth drive, it was simple for them to just use the same type of motor on each unit and generate the other planet speed with gearing within the analog. Spitz (to save money) purchased a lot of parts "off the shelf" so to speak and certainly so with the motors. It was easy to find 2/3 rpm for the planet analogs giving a fastest year in 1.5 minutes. It was also easy to find 8 rpm motors which would allow twelve rotations during that same 1.5 minutes. The problem is that the Moon doesn't go around the Earth once in a little over 30 days. It goes around in a little over 29 days. Since they couldn't find a drive motor that ran at this very particular speed, they just did it with a set of gears on the outside bottom of the Moon analog. Two gears operating together reverse the direction of rotation. That was no problem for Spitz as they just reversed the winding connections and made the Moon motor run in the opposite direction which then was reversed to the proper direction by the gears. Since this motor had a lot less torque then the 2/3 rpm motors and since the Moon analog was the fastest mover, they added a second 8 rpm motor for added power. The two motors are connected by a simple 1 to 1 gear. This second motor rotates in the opposite direction of the first motor through a simple reversal of windings.
I don't know if it is possible to find timing gears with the proper ratio to drive the Moon 29+ day shaft directly, but it is a mute point for me as I need both the one year rotation speed and one month rotation speed to drive the other Moon requirements. Since the Moon's monthly rotational cycle is 29. several decimal points to be accurate, I doubt that a simple combination of toothed gears would work. As a matter of fact I know they wouldn't as I computed a lot of this many years ago when I was thinking of building the drives from scratch.
I probably looked at the same info from Bodine that you have (about $600 for both motor and controller) and was going to go that way until I found out how easy it was to run the exsisting drive motors as variable speed. There is not nearly the controllable range as with the new Bodine drives, but saving $1200 here allows more work elsewhere. The one thing about the A3P worm drives is they add a lot of torque to the system and put very little drag an the motors.
As you build, please give info as to the motors and cost, as I will probably go in that direction for the annular drive.
I would be curious as to what you have found.
The nice thing about DC motors other then their high torque at virtually any speed is that they can be easily reversed by just reversing the leads of the field winding, like you said, a simple switch.
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Post by Ron Walker on Aug 24, 2022 12:01:50 GMT -7
Posted by: Ron Walker Jan 20 2008, 11:38 AM As I mentioned before, the stock timing belts did not exactly fit the Spitz analogs. While there are now enough teeth engaged on each gear to prevent slippage there is some belt "slop" to contend with as the direction is reversed. If the projector is run in a clockwise direction the belt tensions across the top of the pulleys and the slack accumulates along the bottom. If we run the drive in a counter clockwise direction the opposite occurs. It would be fairly easy to adjust for this extra "slop" when setting all of the analogs running in the normal forward direction (counter clockwise rotation) moving from west to east across the sky, the other direction would generate substantial inaccuracies in the sky until the entire drive was again reversed and run forward long enough to accumulate all of the excess slack. Since there is a separate belt between each analog, the slack of the first would have to be removed before the second one would move and so on. It seamed a simple task to add a small idler to take up this extra slack and thus remove these errors. Since the normal operation of the unit was in a counter clockwise direction, the normal tension would be on the bottom side of the belt with slack building up on the top side. It would seem proper to place the idler on the top slack side so that it would not effect the power transfer in any way. Also since we are talking of very slow speed belt movement considering that the fastest year would be only one minute in length, then I was not going to need very fancy idlers. A simple idea came to mind to use a long screw and place over it a simple hollow tube. An extra nut was used to lock the screw in place while still allowing a little play in the tube. This allows the tube to rotate freely on the screw. This tube then is placed against the back of the timing belt to take up slack. A closer view shows the free movement of the tube on the screw.
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Post by Ron Walker on Aug 24, 2022 12:03:41 GMT -7
Posted by: Ron Walker Jan 20 2008, 11:49 AM With all of the idlers in place the slop is reduced to a minimum. It is nice now to be able to turn the main drive gear and watch all of the planet analogs move in perfect synchronism. This is probably going to work very well. smile.gif Now on to the Sun drive.
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Post by Ron Walker on Aug 24, 2022 12:04:27 GMT -7
Posted by: charles jones Jan 21 2008, 01:34 PM Thanks again Ron for the information.
I follow the reasoning for the moon motors to run reverse.
I am 99% sure C&H (store and website) is out of business, although I haven't actually tried to order from the website. I may have accidentally purchased a few of these pulleys when I went to the store. I did buy a few odds and ends, because they were there and very cheap. What I bought had no purpose at the time. Gotta look through the bag of goodies!
The Bodine motors I am looking at for daily and latitude motion are running under $300 each and there is a Minarik drive for half that price that will run two motors. So I may get away with a price tag under $700. These are not right angle drives like the A3P. They are 1/29 hp. However, since both drives eventually transmit motion through a worm gear, that should prevent any damage to motor gearing if the projector is forced to move in any way. I'm hoping they'll work fine.
I am looking for something smaller for annual motion. But as you said it may need a higher torque. I haven't explored that yet. YOu will probably end up getting the annual motor before me.
Right now, first order of business is getting the lathe, making slip rings and then the entire central core of the projector.
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Post by Ron Walker on Aug 24, 2022 12:04:58 GMT -7
Posted by: Ron Walker Feb 23 2008, 07:24 PM QUOTE(charles jones @ Jan 21 2008, 01:34 PM) * Thanks again Ron for the information.
I follow the reasoning for the moon motors to run reverse.
I am 99% sure C&H (store and website) is out of business, although I haven't actually tried to order from the website. I may have accidentally purchased a few of these pulleys when I went to the store. I did buy a few odds and ends, because they were there and very cheap. What I bought had no purpose at the time. Gotta look through the bag of goodies!
The Bodine motors I am looking at for daily and latitude motion are running under $300 each and there is a Minarik drive for half that price that will run two motors. So I may get away with a price tag under $700. These are not right angle drives like the A3P. They are 1/29 hp. However, since both drives eventually transmit motion through a worm gear, that should prevent any damage to motor gearing if the projector is forced to move in any way. I'm hoping they'll work fine.
I am looking for something smaller for annual motion. But as you said it may need a higher torque. I haven't explored that yet. YOu will probably end up getting the annual motor before me.
Right now, first order of business is getting the lathe, making slip rings and then the entire central core of the projector.
Your probably talking about the Bodine 24A-D series motors. I am looking at the model 0196 for the annual motion drive. It runs $240 at the web site.
Is there a special reason why your looking at the Minarik controllers? Bodine makes model 0783 for the above motor which will allow output speeds from 0.56 to 28 rpm at 40 inch pounds of torque which should be much more then enough. Since this will be driving the entire system at the one revolution per month point it will allow operation from one month in approximately two minutes (a year in 24 minutes) to a year in half a minute (a month in two and a half seconds)! That will really be a moving Moon! The nice thing about these power supplies is that you can set the speed ramp up time to as much as 12 seconds which would be very good protection for the entire drive system if it happens to be set for a year in half a minute.
I need to order some more timing belts and gears but I should have this section operational in just one or two more buys. It will be interesting to see just how much torque it will require when everything is connected together. A very small DC motor might be all that's required, but I really like the idea of such a vast range of speeds. How much room available and required is the only sticky point.
I should have some new pictures coming soon as to the next level completed.
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Post by Ron Walker on Aug 24, 2022 12:06:53 GMT -7
Posted by: Ron Walker Feb 23 2008, 07:46 PM Another thing that I'm incorporating into this system is some fairly accurate readouts so I can have a fairly good idea as to that time the planetarium is set for. For the daily motion I would like to get the guts of a 24 hour clock, but a simple 12 hour am/pm clock will do in a pinch. For the year I will have a counter for the actual year and then a 12 hour clock that will show days and months. A second hand could be used to show hours in the 12 hour mode as I'm designing it to show a 30 day month. This is not perfect I know, but is probably more accurate then using the projected ecliptic and much more accurate then the original read out on the A3P console. It will also allow setting without having to turn the lamps of the projector on. Here is the new dial face.
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Post by Ron Walker on Aug 24, 2022 12:07:55 GMT -7
Posted by: Owen Phairis Feb 24 2008, 12:52 PM Hi Ron,
I had a question on A3Ps. I see that the diurnal and lattiude motors are under the base plate and gear driven up at the top of the central core. I see a motor under the star globe which must be either annual or presession, where is the 4th motor and how is it coupled in? I have never taken one apart, and will default to your experience.
Thanks, Owen
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