|
Post by Ron Walker on Jun 13, 2022 14:45:08 GMT -7
Posted by: Philostopher1 Apr 8 2018, 04:14 PM QUOTE(Ron Walker @ Apr 8 2018, 11:47 AM) * That is more then fantastic work!
What are you using for brushes on the slip rings, and how did you make the? We love details and close up picture.
This is some superb work. Also, I would not worry about that 1mm out of round problem. If you were making a jet engine that rotated at 20K rpm I could see a worry. The nice thing about planetariums is they move very slowly and any shifting will be absorbed by the timing belts. This will work fine.
The "protocol TBD" is what terrifies me. Trusting computers has never been a strong point with me. I wish you luck on that one.
Otherwise exemplary work!!! Keep at it!
Thanks Ron!
The slip rings were made by Moflon. Each ring is rated for 10 amps, which is a bit more than I need after all the other bits are on. The brushes are silver and some other precious metal alloy. I forget. there are four brush contact points per ring for low noise and higher reliability.
Yeah, the software side is going to be difficult. I may draw on my laser light show knowledge and go primarily analog with a simple microcontroller. If I get more software oriented I will use Linux over Windows. Maybe Windows XP. There may be some means to run this with DMX like a stage light. Stage lights do pan, tilt, rotate gobos, and change colors or mix effects.
I am trying not to think about that too much. In the meantime, I'm just making sure that I can reliably drive steppers. Once that is done it's just getting the control voltages to the stepper drivers. Those may be generated via analog, digital or "digilog".
I am more intimated by this aspect of the project. Much more so than making lenses....
|
|
|
Post by Ron Walker on Jun 13, 2022 14:45:33 GMT -7
Posted by: Ron Walker Apr 9 2018, 10:46 AM I need to think about this. Being a mechanical person (mechanics are simple and are easy to fix) I always tend to go in that direction. There could be simple way but probably not.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:45:48 GMT -7
Posted by: moonmagic Apr 9 2018, 05:33 PM Again, WELL beyond ANYTHING I could even attempt. Just INCREDIBLE WORK! Really. You and Ron could make anything work. mm
|
|
|
Post by Ron Walker on Jun 13, 2022 14:46:07 GMT -7
Posted by: Ron Walker Apr 10 2018, 10:44 AM The ring that holds the planet projectors, do you know if it (the entire ring) moves at all, or is it fixed in place?
Is there a duplicate ring on the other side that operates when the main body of the projector gets in the way of these front projectors?
I only count five, assuming all five naked eye planets, what does the Sun and Moon?
So many questions.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:46:24 GMT -7
Posted by: Philostopher1 Apr 10 2018, 11:42 AM QUOTE(Ron Walker @ Apr 10 2018, 09:44 AM) * The ring that holds the planet projectors, do you know if it (the entire ring) moves at all, or is it fixed in place? Is there a duplicate ring on the other side that operates when the main body of the projector gets in the way of these front projectors? I only count five, assuming all five naked eye planets, what does the Sun and Moon? So many questions. I don't know exactly. I had their brochures many years ago but I have never seen their systems up close. Especially that one. But the sun and moon would also be produced this way in my system. I didn't clarify that I am planning for a tilted dome. As such it is forward-seated, so behind the audience there will be some occultation by the star projector. I only have 16-18 feet available to put a dome in. I have to stay under the allowed 200sqft shed space (which I will push to the limit) in my trailer park situation. So my Planetarium dome will be about 15.5 feet. There will only be room for a handful of people around the back. 6 comfortably. This keeps the maximum distance available for viewing. Another element of my long term plan is to incorporate edge-blended video from the cove. There is freeware to do this in a dome, and video projectors are getting cheap. By the time I am ready for that I can get 6 hd projectors at 1080 for under $1200. Today it is about $1800 (about $300 ea). Used of course. Did you know there are fully rendered Planetarium shows for domes on YouTube? FREE! There is a link below. Getting back to the optical mechanical, I will have to live with occultation. What limitations there are in the projector I can make up for in video. youtu.be/OUcv3ORj2jc
|
|
|
Post by Ron Walker on Jun 13, 2022 14:46:45 GMT -7
Posted by: Philostopher1 Apr 15 2018, 07:29 PM April 15 2018
Update
Hub and slip rings (Problem)
It looks like I am going to have to rebuild the central diurnal hub for the third time. DAMMIT!
With a tremendous painstaking effort, I got the slip rings coaxially centered and rotating with mimal runout (about 150-200 microns). However they are not parallel and stable on the bearing hub. The top ring wobbles slightly. I can not live with this. It turns out that I overlooked an error in my chop saw. I assumed that the stops were accurate at 90 degrees. They are not. Also this got built overlooking the error in my drill press (which has since been mostly corrected). As such there is a slight angle and axial offset in the parts I mounted and potted with epoxy.
When I designed this hub, I went at it thinking that I would build my starballs with carbon fiber to be lightweight. Since, my discussions here with Ron and others, I decided to just use my aluminum hemispheres. These weigh 6.6 lbs each. By the time all the other parts are in place that weight may increase to >10lbs each. This is a problem for the mechanical integrity of this ABS and epoxy based part. So I am going to rebuild it using galvanized steel floor flanges and pipe nipples. I have to tear the gear\pulley out and clean it all up then rebuild it. I am going to need to involve a machine shop to turn the floor flange plate and make it thinner and the correct diameter for my bearings, or get new bearings.
As it stands now, there is a very high probability that the star balls will flex and rock on the hub potentially damaging the rings or falling off when upside down.
This is the most crucial axis to get right. As someone said, "You can do it right, or you can do it over."
The lower slip ring alignment (rings side)
The rings with the top (brush side) in place
Looking down the edge. The tilt may not be visible in the picture...
|
|
|
Post by Ron Walker on Jun 13, 2022 14:47:57 GMT -7
Posted by: charles jones Apr 16 2018, 10:48 PM Congratulations on taking on building a projector this magnitude. But it is a great hobby to build your own projector!
First, tell me about the Moflon slip rings; I checked them out a year back but never got a quote from them. Chinese I believe; do they have a rep in the U.S.?
Online, they show the pancake rings as a unit, fully enclosed. Your pictures do not. Did you remove the housing? One thing you might consider is mounting the slip rings to a spring loaded which essentially could allow them to float up and down with the variations in the diurnal motion of the unit which may or may not be precise. The upper slip ring unit could be mounted on three very short, very weak springs with a bolt running through it. Think of a reflector telescope mirror mount. The same with the bottom slip ring unit. As long as the two slip ring units are fixed together by some sort of bearing, they would precisely move as a unit. And the spring mounting, could allow for the flex I think you are experiencing. That is why I wondered if you removed the rings from the housing which locks the rings together.
The problems you have encountered is probably a reason why Spitz used a "drum" type of slip ring, eliminating that problem. However, that type of slip ring takes up room vertically, which you don't have.
One thing I noticed about the Spitz A3P, there are all sorts of fine adjustments on almost every component to make it more accurate (due to less than precise machining). So the idea of a "floating" slip ring unit might be something to consider.
Next, I am not fond of pipe flanges for something like this. I would use over the counter metal flanges made for machines. Check out this one from AndyMark.com. I have never purchased from them, but there are others. These flanges are made for ½" diameter steel axle and are 2 ¼" in diameter. They would be more accurate than pipe flanges. A ½" axle is enough for we're doing. And it can be hollow if you want to run wires through it rather than using two sets of slip rings, north and south hemispheres.
Mount a circular plate affixed to the star globe, on it. That plate will need to have a hole bored exactly in the center (which you could do on the CNC). So the holes line up and your star globes should rotate pretty accurately. Spitz had a way to adjust the lamp inside in several directions to make their projector more precise.
Again, mount the slip rings independent of the two circular plates to allow for any inaccuracies or wobble of the plates.
Finally, I would consider making a special jig for a drill press or dremel tool when drilling the star holes. Remember your aluminum star globes will need to be finished (spray paint, or better yet, powder coated inside and out) before you drill. Therefore a jig with coordinates marked will make the procedure much simpler. Time spent making a jig for drilling, will pay off later. Obviously that's how Spitz did it. There pictures of one somewhere on this forum. But you can figure out your own.
I thank you for sharing about the LED and wide angle lens; perhaps you can tell me more about where these can be purchased.
Anxious to hear and see your progress.
[/size]
|
|
|
Post by Ron Walker on Jun 13, 2022 14:48:19 GMT -7
Posted by: charles jones Apr 16 2018, 10:58 PM Another note: the circular plate (or drum) you intend to mount the star globe on can be kept light by strengthening with vertical structs. A sheet metal company could cut "wedges" of aluminum sheet and bend one leg. That you could pop rivot to the circular plate, making it rigid, yet light. Obviously you could also "mold" wedges into the plate using fibre glass material and resin as you have already done in other components.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:49:09 GMT -7
Posted by: Ron Walker Apr 17 2018, 10:42 AM Random thoughts from a week of taxes and a flu heated brain.
You can never have enough slip rings. (I started with forty and ran out.)
Use screws and nuts wherever you plan to use rivets. (Easier to take apart when you need to.)
Keep it mechanical if you can. (A3P's still work fine while STP's just take up space.)
There are millions of dead computers with at least thirty operating systems that are no longer supported. (Things attached to them will probably never work again.)
Build the 23 1/2 degree Earth axis tilt into the central core. (One small DC motor to control a function rather then a computer controlled stepper set.)
|
|
|
Post by Ron Walker on Jun 13, 2022 14:49:47 GMT -7
Posted by: Philostopher1 Apr 17 2018, 12:33 PM QUOTE(charles jones @ Apr 16 2018, 10:58 PM) * Another note: the circular plate (or drum) you intend to mount the star globe on can be kept light by strengthening with vertical structs. A sheet metal company could cut "wedges" of aluminum sheet and bend one leg. That you could pop rivot to the circular plate, making it rigid, yet light. Obviously you could also "mold" wedges into the plate using fibre glass material and resin as you have already done in other components. Hi Charles Thanks for your thoughtful input. I did come across the AndyMark hubs the other day while exploring options. The price is certainly right! About the slip rings: I am using one set of the Moflon MPCB series. These came unhoused. The pancake rings with the housing were still too thick. I am trying to keep the star balls as close together as possible. You know, I really would like to have seen mechanical details of the Spitz STS projector from the Ruben H. Fleet Planetarium. I really liked the design and I understand it produced a very nice sky. Moflon does have US representation. Mine came from China. I have been dealing with Amy for Sales and Ivy for technical support. On my model, you can have up to 12 rings. They just load the brushes and wire them to your specs. For example the lower current wires have four brushes per ring, while the higher current ones have eight with 12 guage wires. The rings and brushes are prescious metals. However, I feel they were too expensive as a general principle, but they were competitive with JInpat, and cheaper than Senring and others. Hopefully they will work out ok. On mounting them I like the spring idea, I'll definitely consider it. In my arrangement only one set of rings is needed, as I am passing wires through the center axis to the other side. This set of rings handles current for all the LEDs and drivers as well as potential voltage controls. However, I am going to install a wireless 12ch DMX512- analog converter under one of the star balls. I can simply add another one if I need more channels. These have multiple functionality, but most importantly I can use DMX to turn on and off stars, setting circles, constellations etc. and control dimming. From the base\yaw axis of the projector the first set of slip rings are the cylindrical type with 36- 2-amp channels. These are Jinpat. These handle the 12-24vdc to the projector, as well as the stepper motors, and encoders. The latitude axis has 2- sets of 12 ch rings. Also Jinpat. I am doubling up the wires for the steppers to provide more current headroom, and using multiples for the main current through the system. This provides some redundancy. All the rest are going to common, and encoders. Drilling the starballs. Yes, I am going to build a simple jig to hold a hand drill or dremel. I'll post pictures of course. But rather than painstakingly locating every pinhole coordinate I am going to use a template. I am using this: www.suopte.com/en/apps/stellasphaera.phpBence Agg was kind enough to increase the number of RA rings (gores) to 48 and the Dec rings to 36 for me for greater accuracy, as well as adding a lable feature indicating star magnitudes. It does not indicate every last one but all the major ones down to 5th. This is enough to quickly identify which size bit to use then I can just aim for the center of a star. It should be close enough for my purposes. 'Stellasphaera' is drawn from the Hipparcos Catalog. A couple weeks ago I was comparing it's plot of Orion to Wil Tirion's while looking at Orion. Stellasphaera looks more correct. BTW, my first starball was a failure (in accuracy) because I didn't take into account that Wil Tirion's Sky Atlas is a conical projection. I scaled and copied the charts and wallpapered them onto my hemisphere. The projector was more for a light show effect anyway. It worked great for that. Here's a picture of it. I gave it away and the guy that has it now installed a quantum dot light source in it. Anyway a "gore" from Stellasphaera lies down pretty well on my hemispheres. Painting; The aesthetic character of my beast. Initially, I allowed myself to be driven by art and potential resale and thought about a Steampunk aesthetic. Instead, I settled on a more modern high tech look. In this I am going for a deep auto finish, probably like the Megastar projector below. The fork on mine is blue and black carbon fiber, and other parts will be similar to GOTO purple like the base, central hub and latitude parts. Wrapping this up, the starballs will be attached to a disk mounted on a short 6" diameter ABS pipe column. This column will slide up and down allowing the starball to be raised and lowered over the lamp. This is to compensate for the gap between starballs in different sized domes. The distance between the balls ranges from 8-10". And I am working on an occultation system. These go in the column around the led \ lens assembly. It took many tries to build these. They are waiting for a coat of flat black paint. I used a plastic bath ball as a form and cut fingers into strips of cinefoil, formed them around the ball and secured it with epoxy. The silver aluminum is pie tin, and the heavy round wire is from coat hangers. There are very small slot car bearings in the corners.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:50:06 GMT -7
Posted by: moonmagic Apr 17 2018, 12:52 PM Now you've got Charles and Ron with you....you are really cooking with gas now! I could not help but laugh at myself as I attempt to follow along. Just the presence of a micrometer in a picture, tells me what you are doing is in a whole other world from the one I live in, but still "fascinating" to watch you work the magic. My world has standards too: However, they are plus or minus a few inches. mm
|
|
|
Post by Ron Walker on Jun 13, 2022 14:50:34 GMT -7
Posted by: Philostopher1 Apr 17 2018, 03:47 PM QUOTE(moonmagic @ Apr 17 2018, 12:52 PM) * Now you've got Charles and Ron with you....you are really cooking with gas now! I could not help but laugh at myself as I attempt to follow along. Just the presence of a micrometer in a picture, tells me what you are doing is in a whole other world from the one I live in, but still "fascinating" to watch you work the magic. My world has standards too: However, they are plus or minus a few inches. mm Hey Gare, Well, The important thing is to enjoy the process wherever it makes you happy. There is something to be said to be able to accept "good enough". I am an INTP personality type. Very introverted, and prefer my own company most of the time. On top of this I have severe psychological issues of perfectionism that my world experience and skills can't match; bordering on delusional. So I'll confess to the fact that I am clinically depressed and I also have some mild schizotypal personality disorder. Fortunately, I am getting by without medication. This project is really kind of a cathartic process, and for the first time it is a project that I can approach without a spouse, client or deadline breathing down my neck. If I was to offer any words of advice or encouragment, I would say, "Enjoy the moment wherever it brings you." Please bear with me as I wax philosophical. The anticipation of whatever outcome one desires tears away from the present moment and we project our minds into a non existent future fantasy (or relive the past) now we are not focused on the only empirical metaphysical reality (at least in terms of human consciousness): that which exists here and now. We all know this, and we create suffering when we go against this reality. I don't want to go too far down this rabbit hole, but the structure of the various politico-economic systems since the dawn of agriculture is responsible for the suffering that Sidhartha observed when he left the palaces of the zamindars to become the Bhudda. Economics -a completely synthetic artificial overlay on our reality- colors every action we take and every interaction with others. From my perspective, this philosophical approach - living in the moment- helps me develop more skills. And it is through philosophy that I can keep my own mental disorders at bay, for the most part. With all of this in regards to planetariums, or anything else I may want to build there is a problem with my particular mental disorders. Schizotypal personality disorder causes disorganized thinking, this leads to errors in actions, which often leads to severe depression for me. This is what it is like if I wanted to build a bird house: I come up with a drawing of my bird house. I think it is a good design. Then I (believe) I have carefully planned it, figured out the dimensions, parts etc. In fact I am SURE that I thought it all through. From the moment of the drawing to cutting the wood this process continues. I check and recheck, think and think trying to anticipate what could go wrong; where the "gotchyas" will occur. So now I have begun to assemble it, and pieces were cut wrong, I am thinking, "I didn't think it through well enough." But in my mind I DID. I tried to cover every angle and anticipate every nuance, but somewhere along the line my internal subconscious dialog distracted me. Maybe 'hijacked' is a better word. Now I am frustrated, now I am thinking I must be stupid, worthless and hopeless, then BAM! a terrible cloud of depression rolls in and paralyzes me. This is the essence of disorganized thinking caused by schizotypal personality disorder and clinical depression. It is hell. Of course, there are people who single handedly build incredibly complex things to perfection. Like this guy: youtu.be/tmNuG15cqNwSo some of this is aquiring a skill set, but the larger part is identifying ones neurological, psychological and philosophical strengths and weakness, then finding a workaround for the weaknesses. In my case I just accept, "If I have to do it over, I will do it over." Then I can only do this to a certain extent where I eventually will throw in the towel of defeat. Of course it is helpful to have a machine shop and optical lab at one's disposal like Zeiss, GOTO and Minolta... Of course, in my delusional mind part of me thinks I can build this: Have fun.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:50:53 GMT -7
Posted by: moonmagic Apr 17 2018, 05:39 PM You are right. It is about the "now." My skills have seldom been what one would call within "close tolerances." While I too feel as though I have pre-planned well, in reality I just go and buy the 1", 2" and 3" wide caulk in order to cover up my imperfections. Perhaps this is why I tend to try to make everything out of wood. I can always cover my errors with an even larger piece of wood. Maybe this is why my baseboards and window trim is all out of 1"x6" stock. (LOL)
To great extent my "projects" are also a type of therapy for me. I'm happiest when interacting with just them. My projects unlike yours, stay at a much less complex level as I simply do not have the background or skill. As has been well documented on this forum over the years anything I acquire for my "collections" is in general working condition when I get it, as I have this fear of not being able to make it work afterward.
There are several recurring themes on this site. One is to "dream big." The other is to keep doing this as long as you are having fun. You seem to be doing both. I am enjoying following along observing your journey. Best wishes of continued satisfaction. mm
|
|
|
Post by Ron Walker on Jun 13, 2022 14:51:16 GMT -7
Posted by: Philostopher1 Apr 17 2018, 06:04 PM QUOTE(moonmagic @ Apr 17 2018, 05:39 PM) * You are right. It is about the "now." My skills have seldom been what one would call within "close tolerances." While I too feel as though I have pre-planned well, in reality I just go and buy the 1", 2" and 3" wide caulk in order to cover up my imperfections. Perhaps this is why I tend to try to make everything out of wood. I can always cover my errors with an even larger piece of wood. Maybe this is why my baseboards and window trim is all out of 1"x6" stock. (LOL)
To great extent my "projects" are also a type of therapy for me. I'm happiest when interacting with just them. My projects unlike yours, stay at a much less complex level as I simply do not have the background or skill. As has been well documented on this forum over the years anything I acquire for my "collections" is in general working condition when I get it, as I have this fear of not being able to make it work afterward.
There are several recurring themes on this site. One is to "dream big." The other is to keep doing this as long as you are having fun. You seem to be doing both. I am enjoying following along observing your journey. Best wishes of continued satisfaction. mm
Sorry, I confused you with Gare.
I hear you with the "fillers". On my fork assembly there are tons of cut errors. I made ABS slurry filled in the mistakes, sanded then decided to cover that with carbon fiber. "Good enough".
I have two power saws. One is a Ryobi semi-acurate compound miter saw, the other is a Black and Decker saber saw. The saber does not cut perpendicular to the surface. There is an angle. All of these parts had to be turned against a sanding drum on my drill press to square them up etc. I also have a three axis cnc router. All I have done with it is draw an Archimedean spiral with a pencil to make sure it worked. It sits lonely. I am a bit intimated to learn to use it and I bought specifically for this project! Geez.
On that wooden hub part, it was a jaggy mess. I sanded then applied carpenters glue to card stock and used that to cover the rough edges like a veneer. Then applied epoxy resin. Good enough.
I spend most of my time fixing mistakes and redoing parts until my perfectionism gives up.
But, I look at the guy making that Orrery in the video I posted with awe.
I have to say, that since the emergence of google it is so much easier to learn things. I used to go to the library and never get the information I needed.
One bonehead simple thing that I never considered prior which has made a dramatic difference in my work is: 1. a sharp scribe for marking. 2. good rulers and a digital caliper 3. a magnifying visor with a light 4. LOTS OF LIGHT on the work. I had to get an inspection microscope as well to mount these tiny leds. When you can see down to 100 microns or better everything gets easier.
|
|
|
Post by Ron Walker on Jun 13, 2022 14:51:36 GMT -7
Posted by: charles jones Apr 17 2018, 09:02 PM Your clever use of materials for the occulting device in the star globes is inspiring. It looks great so far.
Following up on what I called the "floating slip ring:" since both parts are NOT connected to each other, you will have to find a way to have them rotate around a bearing or hub that connects them, and that is independent of the star globe. One good thing I just realized you wouldn't really have to have the "rings" spring loaded. Just a little separation from the star globe to allow for inaccuracy and a connection (perhaps a rod or bolt) from it to a hole in the outer perimeter of the rings. The star globe rotation would in a sense drive the slip ring. There can be all kinds of allowable "backlash" in this type of arrangement.
But all things being said, if you can make the axis more precise, there is no need for any of this. It is always a little experimentation--trial and error, before the final product works.
I have constructed some of my magic illusions over and over till I got the result I wanted.
|
|