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Pico Dome (it's that small)

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#76 averen

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Posted 17 February 2013 - 09:30 AM

What do you estimate the cost of the dome to be?
How much does it weigh?


So far just the dome has probably cost me around $200 to build. I estimate it's weight to be around 100lbs.

Was considering doing something similar but a smaller dome and came across this maker of Plastic Domes .


I had looked at those as an option but I haven't been able to find a 6' dome. Most of the plastic ones seem to top out at 4'. Although you may be able to contact them and see if they can go larger.

Jared

#77 palmer570

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Posted 17 February 2013 - 12:52 PM

From what I saw on the website they can make up to 8' domes but have to inquire about price. I think up to 4' is in stock and over is made to order.

I emailed them to see if they can tint the plastic or how they recomend painting it. Also inquired about how to go about cutting the opening, if they can do it or if I can get my dads coworker to throw it on the CNC.

However I think for my original plan to mount something semi-temporary on top of my RV I'm going to make something like a pentagonal pyramid that the sides fold flat to the roof deck to be locked down.

Edit: Would be like your Pico dome but with flat triangle panels instead of curved.

#78 averen

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Posted 21 February 2013 - 11:05 PM

I pulled the sonotube off...I'm pleased with how it looks!

Posted Image

This weekend I hope to fill a couple of small voids in the concrete and paint it as well.

I also plan to start on the building. I think I can probably have the entire frame completed this weekend. It's a small building. Only 6'x6'x3'. The height is approximate. I haven't measured so that's only an estimate. But I'm probably pretty close.

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Jared

#79 MikeCMP

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Posted 21 February 2013 - 11:11 PM

That looks pretty good, you are getting close to being done!

How are you getting power in there?

Mike

#80 dobsoscope

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Posted 22 February 2013 - 05:52 AM

At this stage think also on 1) how to shed off water from the obs building (ie.) rainwater flowing down the dome and 2) how to prevent the dome from flying off in strong winds!

#81 averen

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Posted 24 February 2013 - 09:14 PM

How are you getting power in there?


Initially I'm going to use an extension cord. Eventually I will trench in a more permanent line.


This was a very busy weekend! Lots of site prep and building. On Saturday I started building the building. I had to pull the dome out of the garage and temporarily set it up on some saw horses to make sure that the dome was placed on the center of the mount (not the same as the center of the pier!) I didn't take any pictures of that...it was a little windy having the dome up on sawhorses made me pretty nervous.

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I got the decking finished and started on the actual building structure.

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As you can see the wall height is pretty low! I'm hoping I don't need to get in there all that much. But even if I do the dome will hinge up allowing me better access to the equipment. The bottom of the dome will be up another 6 inches from the top of the frame.

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Next weekend I hope to have the building completed and the dome mounted (or mountable) on the building.

Jared

#82 palmer570

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Posted 27 February 2013 - 02:29 AM

Looking good! :jump:

#83 astrodog73

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Posted 27 February 2013 - 05:20 AM

Looking great - I feel for you, I have a three month old (and a three year old) - makes it hard to find time for this sort of stuff!

When I did my obs, I installed a caravan/trailer power inlet socket in the wall, I just plug a lead into this when I need power....

#84 Starhawk

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Posted 02 March 2013 - 12:29 PM

How big is the gap around the pier? It looks a little tight.

-Rich

#85 averen

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Posted 03 March 2013 - 12:04 AM

How big is the gap around the pier? It looks a little tight.

-Rich


The gap is 3/8"

Jared

#86 Starhawk

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Posted 03 March 2013 - 10:17 AM

That should be more than any day-to-day shifting. The real board floor is a nice upgrade to the usual plywood.

-Rich

#87 averen

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Posted 03 March 2013 - 10:38 PM

My dad was in town to visit on Saturday so I put him to work. We mocked up the dome on the supports to make sure that it would stay below the fence and that there was adequate room inside for the scopes to clear the frame:

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Today I started on the base "ring" (octagon) for the dome. I still have one missing wheel. Which will be for the rotation motor:

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Then I moved the dome onto the ring and tested the rotation (by hand). Thankfully it seems very smooth and quiet! This week I'll work on getting the rotation motor hooked up to the dome and get some

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I should be able to put in some weeknights now that the sawing and hammering is dwindling down. My son's room shares a wall with the garage and I don't think my wife would appreciate if I woke him up (he turns 8months old on Tuesday.)

Jared

#88 astrodog73

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Posted 03 March 2013 - 11:13 PM

Dads love a project when visiting don't they! :)
Its coming along nicely....

#89 averen

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Posted 04 March 2013 - 11:20 PM

Dads love a project when visiting don't they! :)
Its coming along nicely....


We'll it's partly my dad's fault...

Here he is with his previous setup before they moved from San Antonio. He still has the BRC-250 and TOA-150, but he's now more of a mobile observer and has an NJP.

When they moved he actually offered me this dome, but I didn't have any place to put it at the time. I should have just said yes and stored it. He ended up donating it to a school in San Antonio, still a worthy location for it.

Posted Image


Jared

#90 dmdouglass

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Posted 05 March 2013 - 04:02 PM

Like Father -- Like Son !!

Now just how cool is that ??
You've got to love it.

#91 astrodog73

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Posted 05 March 2013 - 05:40 PM

I think that is the biggest GEM I've seen - or is your Dad really small?? :)

#92 averen

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Posted 05 March 2013 - 09:44 PM

Like Father -- Like Son !!

Now just how cool is that ??
You've got to love it.


For the past couple of years we generally do a father/son astronomy trip to the Texas Star Party. Makes for a nice 4 nights just to get away and unwind too! I hope to continue the tradition with my son when he's old enough to appreciate it and enjoy it. My dad been into astronomy since I can remember but I didn't really start getting interested in it until about 6 years ago.

I think that is the biggest GEM I've seen - or is your Dad really small?? :)


Ya, it's not the latter...both my dad and I are 6'2" and neither of us is exactly skinny. The mount is an AP1200...so it's big...but not HUGE. It's smaller than a Paramount. I think the counterweight extension along with the angle makes the mount look considerably larger than it is.

Jared

#93 averen

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Posted 10 March 2013 - 09:28 PM

I started out this weekend by saying if I got the dome rotating under it's own power that it would be a success...thankfully that happened!

First I started by making some rotation guides. I used 5/16" bolts with Pex (tubing that is commonly used for water in homes) acting as the bearing surface. The block is attached to the base frame with a very long bolt. The block is also attached to the caster frame so it's nice and rigid! There are 4 of these in total.

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Once I was certain that the dome was not going to rotate off of the casters I then started on the motor mount. I even went so far as to create a scale model in SketchUp as I was worried about motor placement. Unfortunately I realized that my initial idea that I had created in sketchup wasn't going to work...but I think my final solution is actually better.

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Initially I had used a smaller hinge (only on the back piece of aluminum). This was too weak to resist leverage that the wheel was putting on the hinge and caused the back of the motor to contact the bottom of the dome! Needless to say this didn't work! The 3" hinge works much better and is considerably stronger. The spring on the left is actually going over another piece of Pex that makes the entire assembly slide up and down very smoothly.

Once this was done I though I was in the clear...wrong. The wheel kept slipping on the motor shaft. So I made a very ugly aluminum piece to capture the cut outs on the motor shaft.

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And finally we have the video proof that this thing is rotating!
:jump: :yay: :jump: :yay: :jump: :yay: :jump: :yay: :jump: :yay:
http://www.flickr.co...en1/8547344512/

There seems to be some additional drag when rotating counter clockwise. I'm not exactly sure what is causing this...

Jared

#94 dmdouglass

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Posted 10 March 2013 - 10:07 PM

Very cool !!
You have worked very hard on this project, and done well.
We are all proud of you.

Now.... to get it mounted.... and something inside !!

#95 averen

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Posted 31 March 2013 - 11:40 PM

Had a busy weekend working on the shutter. I decided to go with a cable shutter to keep as much of the zenith clear as possible. Overall I'm pretty happy with how the shutter works! I need to figure out a way to make the cable wind up nicely every time and I need to add some tensioners as well.

Here's a shot doing the initial cable runs, before the motor was installed. The motor is installed at the back of the dome (but I have no pictures that are this wide with the motor...

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The cables stay within arcs of the dome so as not to interfere with the telescope. The cable on top connects to the shutter. The cable on bottom runs back to the motor.

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The motor is mounted on the back of the dome and it's mounted low. You can see the rotation guide at the bottom for reference. Unfortunately the cables don't always wind up as nicely as this. I need to figure out a way to make them wind more reliably. However for the most part when they overlap it's not a problem. But they did bind after playing around with opening and closing the shutter once...and since the motor has enough power to rip the shutter apart I would prefer to avoid that from happening!

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Speaking of the motor power I was initially worried that it wouldn't be enough to open and close the shutter. But because of the small winding bar it has more than adequate power. It's probably too powerful.

I still need to install the limit switches for the shutter. I'll do that sometime in the week. I also managed to let the magic smoke out of one of the motor controllers so I'll be ordering another one of those :-/

Jared

#96 averen

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Posted 14 April 2013 - 08:41 PM

Sorry for the lack of photos...I'll try and get some up soonish!

The shutter is now complete with both limit switches installed and it works very nicely! I notched out the removable shutter to make room for the pulleys so it's back in place too.

Next up is the building "flange" (not really sure what to call this...the piece that goes from square to circle). I know how I'm going to do it I just need to get it done. Maybe some interior painting will happen too.

I haven't bee focusing as much on the dome because I'm headed to the Texas Star party in about 4 weeks and have other projects that need to finish up before I head out.

Thanks,
Jared

#97 1965healy

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Posted 15 April 2013 - 12:06 AM

Could you use a coarsely threaded rod instead of a smooth one to act as a guide for the cables to spool/wrap on? Or a larger diameter rod? The larger the diameter the fewer wraps and the less tendency for the cable to jam/bind. It could also run slower since each rev accomplishes more take up of the cable. Just spitballing, I'm an audio engineer, I'm not a mechanical engineer.

#98 averen

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Posted 09 September 2013 - 11:14 PM

Wow, last post in April...it's been too long!

So a couple of weeks ago I decided that the dome would be completed before this project was 1 year old! And looking at my photo stream on flickr the project turned 1 year old today. So "Happy Birthday Dome" you've taken entirely too long to build! I'm not completely done yet...but I'm darn close.

Somewhere in this thread I had mentioned contemplating making the dome a "walk in" dome but decided to leave well enough along and just have the tiny door. That has changed.

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The walk through is probably one of the better decisions I've made with this dome. It's held in place by a couple of latches (commonly used to secure windows). The majority of the force is taken by a couple of oak blocks attached to the uprights.

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After I had cut the dome and flange that took me so long to build I started priming them both. You can see that the flange has been primed in the background as well.

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After the dome and flange were primed I started on the building. I had actually built the building once before but since it sat outside for so long with no structure, and the frame was not pressure treated, it began to rot. So I removed all the non-pressure treated wood and started anew.

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And yes, that's the door that I was planning on crawling through. I'm very glad I made this "walk in".

Finally with the building done and the flange in place it was time to paint the flange and dome (the building is painted in the picture above). As we were discussing the logistics of carrying the dome out it began to rain. We quickly covered the flange and waited about 15 minutes for it to pass then we carried out the dome and painted the flange and dome. After which we moved the dome onto the structure.

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Here's a shot with the walk through open. There are 3 pieces which must be removed, plus the door opened and shutter retracted. If you click through the pieces are annotated.

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In normal operation this is what the dome will look like. The lower shutter will be installed unless I need to get below 35 degrees.

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And for a sense of scale here's a bad shot of me and my son standing in the opening. Needless to say this is an imaging only dome :-)

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At this point I think the dome is about 99% done. The rotation and shutter work well. I need to make a couple of minor improvements to the shutter limit switches and fix an area where the dome skirt rubs on the flange. But other than that it's pretty much done.

I'm hoping to get first light this coming weekend. Where I'm sure I'll find some other issues about dome slaving or something.

This has been a pretty fun project and it's a real sense of pride knowing that I made 100% of the dome as well as the motor controllers and everything that runs it! I can't wait to get some use out of it!

Jared

#99 nytecam

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Posted 10 September 2013 - 03:56 AM

Nice work - small has a new meaning in that photo - enjoy the ride and keep us posted with you future imaging :-)

#100 Midnight Dan

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Posted 10 September 2013 - 06:10 AM

Nice job Jared!

One question - what holds the dome down to the rest of the building when not in use? I didn't see anything in your photos and Id be concerned that a big windstorm could pull it off.

-Dan






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