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Seat/Stool on tracks.

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#1 ahopp

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Posted 14 February 2013 - 08:37 AM

I have a mobile observatory with a wood deck floor.

I want to install a stool on a set of round tracks so that I can move in a circular orbit around my scope. I can not seem to find anyone who has done such a thing. Any ideas would be greatly appreciated.

Tony

#2 Agatha

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Posted 14 February 2013 - 09:05 AM

Wheee! :)

Sounds interesting.

Best, Linda B.

#3 okieav8r

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Posted 14 February 2013 - 09:11 AM

Scott Losmandy, who makes equatorial mounts and these tracked items for the movie industry could probably help you. Probably wouldn't be cheap though. Check it out.

#4 zippeee

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Posted 14 February 2013 - 09:27 AM

Here's an interesting DIY technique that I think could be modified for your purpose.

#5 Dick Jacobson

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Posted 14 February 2013 - 09:33 AM

Idea #1: Put a large lazy susan bearing (see Lee Valley or VXB) on the floor surrounding the scope and mount a stool on it.

Idea #2: If your scope is on a pier, buy or make a ring that fits loosely around the pier, attach a bar pointing radially out from the ring, attach the stool to the outer end of the bar. The stool is on casters which maybe should be oriented parallel to the circle. How to make the ring? Maybe use a smaller lazy susan as in idea #1, maybe a drum shell rim, maybe bend multiple layers of thin aluminum bar into a circle. Or you could cut a ring out of plywood as amateur telescope makers often do. Or you could go the deluxe route as I did and buy a ring roller (see tubing roller).

#6 Midnight Dan

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Posted 14 February 2013 - 09:47 AM

I think Dick has some great ideas. I was thinking of his #2 idea as well.

There are lots of issues with using tracks. If they stick up from the floor, you'll be tripping on them in the dark. Recessing them in the floor is a BIG effort, especially with a circular track. And just getting circular tracks of the right size sounds like a custom fabrication job = $$$$!

-Dan

#7 ahopp

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Posted 14 February 2013 - 09:56 AM

I actually thought of and tried Idea#2 and it was problematic. The castors on the chair are just no smooth enough, plus they bind and lock.

Idea#1 looks more promising, but, dangerous if not in a locked position when not in use. You can imagine stepping on it and having it move under your feet.

I do not mind spending money on it, but, it has to be a stable reliable solution.

Tony

#8 zippeee

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Posted 14 February 2013 - 10:30 AM

What are the dimensions of your pier? Photo?

A cantilevered (yet removable) arm on a DU bearing of some sort could easily be made, providing you have access to machining and manufacturing services. It may cost you a bit but it would be better than anything you could piece together with off the shelf parts. My company makes stuff like this all the time (albeit mostly on a commercial level).

#9 zippeee

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Posted 14 February 2013 - 10:39 AM

This is also assuming your pier can handle the loads involved without affecting the views.

#10 ahopp

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Posted 14 February 2013 - 10:48 AM

It is a mobile observatory, so, no I can not attached anything to the scope base.

Tony

#11 CharlesW

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Posted 14 February 2013 - 10:50 AM

I would go to a model train store and talk to them. They might have a track gauge that would support your weight and have the correct circumference. Might have the do an inner and outer ring. I would think it would be much cheaper than a custom job. Of course, an adjustable height office chair on a rolling base might do he same thing and be much more comfortable.

#12 zippeee

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Posted 14 February 2013 - 11:03 AM

It is a mobile observatory, so, no I can not attached anything to the scope base.


Well that solves that problem!

So a track is your only option. How stable is the floor (as far as flexing goes), flat?

#13 zippeee

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Posted 14 February 2013 - 11:53 AM

an adjustable height office chair on a rolling base might do he same thing and be much more comfortable.


I was going to ask the same thing. Are you currently using a castered stool and finding it's not working for you?

#14 ahopp

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Posted 14 February 2013 - 12:32 PM

Castor chairs just do not roll as smoothly as I would prefer. And, yes, this observatory is custom built to my specs. and the decking is very sturdy.

Tony

#15 dan_h

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Posted 14 February 2013 - 12:56 PM

The castors on the chair are just no smooth enough, plus they bind and lock. Tony


If the chair is to move in a fixed circle, then there is no need for swivel casters. Use fixed wheels attached with the needed angle to roll in the required circle. These won't bind. I like the idea of a single pole or bar attached to the central bearing around the pier to define the range of motion.

I thought about a platform similar to a DOB base but this has the disadvantage that you would have to get off of it to adjust the position.

You might get more useful ideas if folks had a better idea of what it is you are attempting to do. Does the scope have a fixed position eyepiece or will your chair also have to move up and down as well as in and out as it circles the pier?

dan

#16 zippeee

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Posted 14 February 2013 - 12:58 PM

What about a mat? a large piece of seamless linoleum with a hole cut in the center for your pier. It comes in various thicknesses and densities, and will smooth out the floor. One potential problem I see with a track is you may not have enough radial adjustment. I personally like to be able to move close to and away from the scope as needed. You could also custom make a stool base with oversized casters that roll better.

#17 ahopp

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Posted 14 February 2013 - 01:37 PM

I like the idea of a mat to make the castors roll smother. May try that. Using fixed angle castors could be problematic. It will surely get out of alignment from time to time. I would have to pick the chair up and reposition it.

Tony

#18 csrlice12

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Posted 14 February 2013 - 02:00 PM

you could always install a track that the chair could ride on like sliding glass doors have (only round and not straight). The chair "wheels" would have a slot in the center that would ride on the track. Barring your tripping over the chair, it should stay in place.

#19 Dick Jacobson

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Posted 14 February 2013 - 02:52 PM

I actually thought of and tried Idea#2 and it was problematic. The castors on the chair are just no smooth enough, plus they bind and lock.

Idea#1 looks more promising, but, dangerous if not in a locked position when not in use. You can imagine stepping on it and having it move under your feet.

I do not mind spending money on it, but, it has to be a stable reliable solution.

Tony

If you make your own caster assembly, you can surely find wheels that will roll smoothly. For example, McMaster-Carr has hundreds of caster wheels, some with capacities of thousands of pounds (see McMaster Casters). In general larger diameters and harder materials (polypropylene, phenolic) roll easier. Skateboard or scooter wheels might do the job.

Regarding the lazy susan idea, I can imagine a self-locking feature where the chair is mounted on a rocking bar with a rubber pad on the opposite side that unlocks the ring when you sit on the chair, locks it when you get up.

Happy orbiting!






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