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Equipment Discussions >> Observatories

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stmguy
sage


Reged: 10/11/12

Loc: Western NH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5641972 - 01/25/13 06:11 AM

I have a 10x10 OBS with a 32" slot , 10" Newt on Equatorial Mnt and wish the slot was wider at times to visually find things
Norm


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RogerRZ
Whatta you lookin' at?
*****

Reged: 01/09/06

Loc: West Collette, NB, Canada
Re: Observatory from a Fiberglass Storage Tank new [Re: stmguy]
      #5642639 - 01/25/13 01:48 PM

Mine is 28", and when I image with the 70mm, it's not too bad, but with the C8, I find it a bit narrow. I suppose it wouldn't be too bad with a fork mounted alt-az, but an eq mount has you looking across the shutter in some weird positions. Thing is with a small dome, there's a limit on how wide you can go without it being too wide.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: RogerRZ]
      #5642894 - 01/25/13 04:10 PM Attachment (91 downloads)

Quote:

Mine is 28", and when I image with the 70mm, it's not too bad, but with the C8, I find it a bit narrow. I suppose it wouldn't be too bad with a fork mounted alt-az, but an eq mount has you looking across the shutter in some weird positions. Thing is with a small dome, there's a limit on how wide you can go without it being too wide.




That's what I figured too... The bigger the hole, the less function it has as what it was intended for in the first place (at least in my case for the stray light). I'm going to try cutting the 30 inches and past zenith at 25 degrees. I think this will work OK.

I did some measuring last night and found that it's only out of round by 1/4 inch, which is astounding considering how much fiberglass will shrink.

I'll cut my shutter out over the weekend, and get it cleaned up of all the lichens and moss growing on it, as well as all the oxidized epoxy resin and loose fiberglass chop. You can see this where I started wire brushing in the attached pic. There is also a form seam from the lay-up when the manufacturer built the tank. It's a perfect center line to measure from, so everything will be nice and symetrical with the dome.

I may also start on the inner ring that will be the bearing surface for wheels to run on. My thoughts on the bearing surface would be to keep it square in shape to minimize distortion of the ring. My thought is, is to counter sink wood screws through the dome and into the ring, along with polyurethane glue.


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Bob Griffiths
Getting Grouchy
*****

Reged: 10/10/05

Loc: Frederick Maryland
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5642973 - 01/25/13 04:58 PM

I believe ...but do not remember the exact measurements but my 8 foot Exploradome has a shutter 28 inches wide...(you should be able to get the exact size on the ED web site) ..

Never ever been a problem or even seem to be too small...BUT I DO NOT IMAGE ...

Bob G.


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: Bob Griffiths]
      #5644514 - 01/26/13 02:35 PM

I figured out the problem with the photos... It's MAC IOS5 incompatibility with Windows7. They come in flipped in emails from my IPhone, so I rotated them. They look fine from my computer but are upside down on iPad or iPhone! I'll fix this Monday when back at the IBM machine (sorry for the poor graphics)!

Today, I square cut the bottom edge of the dome by building a jig to fit over the reinforcement. I scribed a line around the circumference of the dome, and used a jigsaw with a diamond blade to trim the edge off. Hopefully this'll be square enough that I won't have issues with rotation later.

I also wire brushed the entire dome surface to remove all of the dirt and loose glass chop. Did this prior to scribing and cutting so it would be easier and truer.

Also cut out the shutter. Went with 30" x 7'4" to arrive at the dimensions I mentioned before.

Working ahead, I'm going to try the skate wheel route even though it was mentioned this may not be the easiest turning assy. I thought about using holesaw cut plywood wheels for this, but would need the bearings, and at $3-5 apiece, I'd need a bunch at a fairly large expense! Looked all over the Internet, and finally found my wheels and bearings from toysRus in the form of 2 pairs of in-line skates. The 2 pair came to $30... They were on sale for $20/pair, but the second pair would also be marked down an additional 50%, so all in at $30 for 16 wheels and so-so bearings.

Ill post follow-up pics Monday.

Next up is the lay-out of the bearing surface and install.


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Madratter
Postmaster


Reged: 01/14/13

Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5644828 - 01/26/13 06:00 PM

Never say never, but I never intend to use anything with rubber wheels again on an observatory. They go out of round too easily and then everything becomes a mess.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: Madratter]
      #5647641 - 01/28/13 09:22 AM Attachment (84 downloads)

Here's some pictures I took of the progress over the weekend...

Edited by berlinstar (01/28/13 09:23 AM)


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5647644 - 01/28/13 09:26 AM Attachment (74 downloads)

Here's the Dome with 3/4" birch ply bearing surface build and install...

Edited by berlinstar (01/28/13 09:26 AM)


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5647652 - 01/28/13 09:28 AM Attachment (76 downloads)

I got my skate wheel trial all worked up and installed as well, to the base. Base is 6' high. I used the same jig to ensure that the top that mated with the dome edge would be square, then cut it off.

Edited by berlinstar (01/28/13 09:29 AM)


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5647661 - 01/28/13 09:32 AM

The base in the pic above hasn't been cut yet on the bottom surface. I cut it flush with the bottom reinforcement ring. I have to cut in the entry door yet, and hopefully will get that completed this week through a couple of evenings. If the weather holds for this weekend, I'll get to try the dome out on the base. At present, my calculations are ~13# per wheel provided the dome is complete at 200# total.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5647687 - 01/28/13 09:42 AM

I also hope to have a design finalized for a shutter. My initial thought is two parts that will slide under each other and to the back out of the way, but at the same time be able to use them separately to block out the stray light. I'll build this out of the 3/4 ply stock and 1/8 lite ply, then glass it all.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank new [Re: berlinstar]
      #5652768 - 01/30/13 04:58 PM Attachment (85 downloads)

Weeks are terrible to get anything done, especially through the winter. Just not enough daylight, which is usually welcomed, but there's too much cloud cover for viewing anyway.

In any case, I found some time to layout a cardboard template for the shutter frame. I needed about 2 3/4" to clear the curvature of the dome in the center. I made the template 4" high to accomodate the inner frame for the lower shutter, and I hope to fit an outer shutter over the entire frame then (at least that's the 2 minute plan).


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csa/montana
Den Mama
*****

Reged: 05/14/05

Loc: montana
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5652896 - 01/30/13 06:05 PM

That's looking really nice! It really cleaned up very well.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: csa/montana]
      #5653106 - 01/30/13 07:50 PM

Thanks! Like I said, if the weekend holds out on the weather, I hope to trial fit the dome to try out the rotation. Hopefully can get the shutter framing completed, and at least mounted onto the dome. I can see this isnt going to be easy because out of square is going to make for an unworkable sliding shutter.

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Bob Myler
Carpal Tunnel
*****

Reged: 05/18/06

Loc: St Louis, MO
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5654770 - 01/31/13 05:48 PM

Shame about that hole at the other end - would have made a perfect dome for a home planetarium!

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: Bob Myler]
      #5656154 - 02/01/13 11:12 AM

Wow! Never thought of that one. I actually have the piece I cut out of the end I'm using. Trying to figure out if I should utilize the cut out for the shutter pieces, or build them out of lite ply. I need to get the framing in-place, then intend upon using the scrap fiberglass pieces cut from the tank body as bearing surfaces. From there I can assess whether I have enough space for using the cutout, or just build a lite ply set of shutters.

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5660661 - 02/03/13 08:15 PM

Well, the weather did NOT cooperate this weekend at all. In the teens and 3-4 inches of snow. I planned on tugging the base back into the garage for cleaning up and cutting the door in, but found my tractor had a flat tire and it broke the bead off the rim, so no way to get it in the garage!

I did manage to get the shutter framing at least cut. I'll be working toward mounting these up hopefully this week.

It's another busy week. The Gemini II kit shows up this Thursday, so I'll be playing with that too!

Should have some new pics of progress sometime shortly.


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5667120 - 02/07/13 01:45 PM

Gemini II kit came today

This week, I've been working on mocking up the wood shutter framing with the dome. It sounds easy, but proving more difficult. Reason being is that I made a 30 degree radius cut on the inside cut of framing to accomodate the dome. Since I cut it with a scroll saw - it's uneven and left gaps between the dome and wood frame. Time to get the belt sander out and fit it as best I can, then check for squareness. Compounding this, is the fact that I have several pieces. Will need to get all pieces together, then fit them to the dome. Hopefully I can get this behind me this Sunday, as well as get the base drug back in the garage!

Now if only a good warm, clear night to try out the GII!


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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5673980 - 02/11/13 12:33 PM

Can you say: Scroll saw gone wild??? . Lots of clean-up work with a rasp over the weekend on that framing! None the less, its fitted. Still have to box the ends in, but atleast the rails are screwed to the dome and fairly symetrical from initial observations. I have some time this week to do some more, so I'll post pictures then!

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berlinstar
super member


Reged: 03/28/11

Loc: Berlin Center, OH
Re: Observatory from a Fiberglass Storage Tank [Re: berlinstar]
      #5673983 - 02/11/13 12:35 PM

Oh... Did get the Gemini II installed on the G-11 this weekend too! Now for some clear skies!

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