Teaching People to Dream
Realizing a home-built planetarium: specific issues (planet projection, dome construction, cost)
Greetings. I'm a one-man planetarium builder with a lot of motivation, some engineering skills, a too-limited budget, yet a continued desire to perfect my projector. I'm working on refurbishing my 16" drum-type projector and fitting it with ancilliary projectors and axis drives that I could only hope to do when I started this project as a teen. The real strength of my device is the drum, which includes all the stars of Norton's Star Atlas and condensor lenses for the brightest 100+ stars.
I'm wondering if there are people out there that could provide me with advice on two thorny issues for me: (1) creating planet projectors and (2) dome construction. I have attached two files. One shows what my projector looked like (schematically) some 30 years ago (it was based on the Steven B. Smith model that was featureed in Sky and Telescope back around 1974). The diagram shows the star cylinder perched on a two-axis mount that allows for the attachment of a planet cage (the cage is labeled by the letter D). Currently, I've completely dismantled this set-up and am working on refurbishing the star drum and the mechanical linkages. Basically, I'm starting over, with the exception of having that highly valuable star drum. The second attached image shows the star drum (stripped of all condensor lenses, etc.) in it's current "starting over" phase. Only the diurnal drive remains.
My goal is to donate the finished product to some local organization that would grant wide access to kids and other interested parties. I'm strongly motivated to contribute to the revitalization of a general societal interest in science ("inquisitiveness") and am thinking that a planetarium can provide a really good vehicle for this goal.
Anyway, I'm wondering if there are any folks out there that can lend advice, guidance, etc. regarding two design areas that are looming (or others that they can think of)....
1) design and/or construction of a planet cage. My original design (see attached file) had a very primitive system that could independently move 3 projected "dots" along the general plane of the ecliptic (see item labeled "D" in the attached schematic). This design was deficient in several respects, but did offer independently positionable planet images (points of light). I'm very interested in learning how to create a more sophisticated planet cage that would include at least three planet images (say, Jupiter, Venus, and Saturn) as well as projectors for the sun and moon. I am intimidated by the thought of creating the gearing used to recreate good relative motion or all the other complexities. My new design will minimally feature independent optics for each image, but I'm pretty clueless as to how to create realistic motions and adjustments.
2) Dome. I'm estimating that my projector could cope with a dome in the 16 to 20' range (although I need to do some empirical tests of general projected image quality). I'm thinking that a segmented, aluminum-panel design would be good in that it would offer the possibilitly of modular construction and dismantlement and repositioning into another facility. I'd be willing to do a lot of labor. I don't have a finished design for the repeated units (templates for the panels), although I do have one possible design. Also, this is an "expense problem". In my fantasy world, I wish i could find a benefactor or corporate sponsor that would be willing to help defray the costs of the dome material (sheet aluminum isn't cheap).
Finally, I suspect that I have a lot of other questions/issues that will crop up. However, now, I want to get my projector "more operational" (with planets) and also start thinking about the possibility of a dome. I know that there are small inflatables, but given the size of my projector and star-to-planet parallax issues -- along with the fact that i think this projector can "do" a bigger dome, I'm shying away from that approach.
Thanks any and all out there.
I'm wondering if there are people out there that could provide me with advice on two thorny issues for me: (1) creating planet projectors and (2) dome construction. I have attached two files. One shows what my projector looked like (schematically) some 30 years ago (it was based on the Steven B. Smith model that was featureed in Sky and Telescope back around 1974). The diagram shows the star cylinder perched on a two-axis mount that allows for the attachment of a planet cage (the cage is labeled by the letter D). Currently, I've completely dismantled this set-up and am working on refurbishing the star drum and the mechanical linkages. Basically, I'm starting over, with the exception of having that highly valuable star drum. The second attached image shows the star drum (stripped of all condensor lenses, etc.) in it's current "starting over" phase. Only the diurnal drive remains.
My goal is to donate the finished product to some local organization that would grant wide access to kids and other interested parties. I'm strongly motivated to contribute to the revitalization of a general societal interest in science ("inquisitiveness") and am thinking that a planetarium can provide a really good vehicle for this goal.
Anyway, I'm wondering if there are any folks out there that can lend advice, guidance, etc. regarding two design areas that are looming (or others that they can think of)....
1) design and/or construction of a planet cage. My original design (see attached file) had a very primitive system that could independently move 3 projected "dots" along the general plane of the ecliptic (see item labeled "D" in the attached schematic). This design was deficient in several respects, but did offer independently positionable planet images (points of light). I'm very interested in learning how to create a more sophisticated planet cage that would include at least three planet images (say, Jupiter, Venus, and Saturn) as well as projectors for the sun and moon. I am intimidated by the thought of creating the gearing used to recreate good relative motion or all the other complexities. My new design will minimally feature independent optics for each image, but I'm pretty clueless as to how to create realistic motions and adjustments.
2) Dome. I'm estimating that my projector could cope with a dome in the 16 to 20' range (although I need to do some empirical tests of general projected image quality). I'm thinking that a segmented, aluminum-panel design would be good in that it would offer the possibilitly of modular construction and dismantlement and repositioning into another facility. I'd be willing to do a lot of labor. I don't have a finished design for the repeated units (templates for the panels), although I do have one possible design. Also, this is an "expense problem". In my fantasy world, I wish i could find a benefactor or corporate sponsor that would be willing to help defray the costs of the dome material (sheet aluminum isn't cheap).
Finally, I suspect that I have a lot of other questions/issues that will crop up. However, now, I want to get my projector "more operational" (with planets) and also start thinking about the possibility of a dome. I know that there are small inflatables, but given the size of my projector and star-to-planet parallax issues -- along with the fact that i think this projector can "do" a bigger dome, I'm shying away from that approach.
Thanks any and all out there.
- Attachments:
-
-
Planetarium-EarlierDesignDrawing.jpg, 418 KB -
Projector-LowRes-1.jpg, 409 KB
-
Replies to This Discussion
-
Permalink Reply by Owen Phairis on -
There are two good sources of information on home built planetariums:
The Homebuilt Planetarium Association (HPA) by Mr. Gary Likert who has the original Steve Smith Drum.
The second is Observatory Central which has a whole section devoted to home built planetariums.
There are links to both sites at the: Planetarium Projector Museum ( www.pictorialism.com )
Owen
-
Permalink Reply by Gary Likert on -
Thanks for the nod Owen, and Charles and I have already been comparing notes in email, it is SO GOOD to see another drum!!! I would bring this over to Obs Central, I think engineers like Ken Miller, Ron Walker, Charles Smith, and more could really address planet cage gearing etc, as well as the museum having examples of so many classic machines. There are probably many great people we have yet to meet here as well! gare of the HPA
-
Permalink Reply by Gary Likert on
-
oops Charles Jones ... sorry gare
-
Permalink Reply by Charles Miller on -
I apologize if I am posting at an inappropriate spot. I'm not quite sure I'm properly oriented to the related websites.
c.m.
About
© 2009 Created by Rovy Branon (Admin Account) on Ning. Create a Ning Network!
