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datman

DIY Portable Temporary Observatory

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Hi

I have a limited viewing area and a small amount of light intrusion mainly from street lamps and my own house (wife refuses to walk around with a miner's helmet). Since this area is on the decking outside the house a permanent structure is out of the question. I do have an area at the side of the house where I could store a dissassembled observatory.

After some experiments with a tent I decided that the level of reduction in stray light made it worthwhile to consider some sort of temporary observatory.

I have been looking at one version of octagonal observatory made from tubing. I can just fit a 7' diameter onto my viewing area. I know this is a bit small but according to my mockups and drawings should be OK for one coordinated person. height is about 7'

Once you've figured out where to start the design is easy and self configuring. IMO the $25 charge I've seen for plans is a bit optomistic. With the parts available there is really only one way to do it!

Anyway I found a couple of UK suppliers and have ordered the parts in black PVC. Cost so far for tubing and wheels £180.

I was wondering if anyone else is interested in something like this, if so I could take photographs and provide a description of progress.

n.b. if 7' is not to your liking it is very easy to alter the dimensions.

Just send £200 to my PayPal account and I will provide plans so detailed I can guarantee you will be in a state of confusion for months :-)))

Just kidding!

If there is enough interest I could explain how to do the calculations (with diagrams) to make your own. This is after all the DIY section.

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"I have a limited viewing area and a small amount of light intrusion mainly from street lamps and my own house (wife refuses to walk around with a miner's helmet). "

You could change all the bulbs in your house for red ones :icon_confused:

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Must admit I'd be very interested. I saw a finished octagonal one from a posters photo's on here, and asked him about it. Looks really good and efficient (I won't post a link without permission), and is one I'm about to do myself. His is on decking, but mine will be on grass so looking at sinking poles into the ground. I'm also on the coast (100 yards) and it get blowy, so I need some stability.

I'd be grateful for any plans etc that would help.:icon_confused:

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"You could change all the bulbs in your house for red ones :p"

Oh no! Why didn't I think of that I've gone and ordered the bits ;-)

Talking of which they turned up today 8 x 5M of tube and a box of bits. Can't start yet though I have some decking to finish of first.

I've started a "how to do it" it's more along the lines of explaining how to design your own size of observatory rather than "Plans to build a 3 metre wide observatory".

I'm finding it of benefit because while trying to explain things, I've discovered a couple of misconceptions I had too.

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Hi

Bad day for decking so made a start on the Observatory. Not having done this before I was being cautious, a long piece of tube can be shortened but a short piece is more of a problem. Although people use 25mm/1" tube I decided to use 32mm which has a wall of almost 3mm against just under 2mm for 25mm tube. The cost difference was only £26. It will be heavier but I'm not planning on taking it far (stored at the side of the house).

I laid out what should have been the middle section and did a few experiments to see how the roof would join. At this point I spotted a flaw in my layout. I changed the fittings so this now shows the base but with the flawed layout.

BNBase1.jpg?attachauth=ANoY7cqhTiUMl3htqU7a7OJMAN7DnqQLqf5GUWVH6p6fO9h55EW14P3DW7M7-OBtrqdzDBzZcKFuDJXFi0SgHuBFwFCJb2Zdm31waKVJTMY8Cp3kEW2NRHz2y19V7M79xGABlQBRpnXYIwpLti-B-5qow4vuPz9piDzUnPjINGwccs4andMGvQ4braYwQJ5_JzgOKvlzBQFymfiy_XjR2BlFivn0am-VGA%3D%3D&attredirects=0

At first glance everything looks OK. Here is a closer look at the joints, there is a hidden 40mm piece of tube between the Tee and Elbow.

NGBaseCU.jpg?attachauth=ANoY7cotIWCyU6Viw0aLf0MQH9KfozpXOQ4AjBu4GNjvoiUCcvxBjRaOxYKjGNqaYanIfpAxgOdsuIwxJAohpr4jID-PSn0E-VIPA7T0WsH2AJNa04ymhy6u6USRf1nADgISwvj6auxx6MBztbE2_aSmesbR4YrHXze9xlzvP2ledsUBbpExnjgqIQKaX8C_uPWf-6bdfRk_-Kk6-JIoUUg0Kbs7_-BjLQ%3D%3D&attredirects=0

Corner to corner dimensions are good but then I realised that there would be a problem when the uprights meet the roof joists. The Tee uplifters are offset. After a bit of thinking I reconfigured everything to overcome this problem. The dimensions are now incorrect but the tubing is still longer than my estimate and the wheel support has yet to be fitted. One advantage is the telescope "window" is now slightly wider.

OKBase.jpg?attachauth=ANoY7coOHhli8c4qcAlhi659g-4OVJqPV8XarlQRgWG4hNlZTkA01wLaNZLLKkGtUYj2exWkQHcgN0AVK6LfEcOmIdIv3bOsDG7PgQluMuoMM33YUqS3i_8wQqXQJAQcTyxLC5QidODYBRjxAsmOY846gNlAOZz5Zuf9WIlmeSL7FMFPfdCrwc-dOREVoWaQlAEiBQaymOCodvOkL4H6rXVatqU_ciLsyQ%3D%3D&attredirects=0

When the risers meet the roof they will now be in line with their opposite number.

Close up of the jointing here.

OKBaseCU.jpg?attachauth=ANoY7cq0cWxcSIqf3S8KM6dlSnmpBoySFNCg3qRMbzaYbWSnyURSnvvpCCAr9S-n7Cw9sMfYuKTeSIyEP5dVSzvxyNwLIBAQeC7kPlJR5UXaSFh1oWgiL_4HBRAVZ0kQrahYLoC46NsLve2Vr6uPXPge_dZbzM1mbOrfl5R6CX99NQfKxHal85OLLvuCnW9u0cUPdL7c8g-ekyOd1uVgn0PshnH51eio-Q%3D%3D&attredirects=0

I have done a few experiments to work out the best placement for the wheels and their supports . Next update will show how these were made and fitted.

After a bit of thinking I think the first layout will work, the roof will be slightly skewed but will not notice. At the moment I have not commited to either layout. I won't have to resize the tubing if I stick with the first option.

Bye

Edited by datman

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Hi datman, i cant see your pics, dont know if it's my comp?

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Hi

Not your computer they've disappeared.

BNBase1.jpg?attachauth=ANoY7cpNLNO1cUdXT2aOXRhhp8goSA6furx8UPPlSZgw8L_GUBUyZqRXplALV_NC500bWrM6FpugG9yKpJUuNbaitb1fyFPhmWvrAxQQCV78cNvfnL8Nn9kGT-lW5dFCbjUuc8jb9McWtp1BaLnlHFzAJkCHAgf0HsgkSQLrEmhjRbaTRbgUkOCDJ3EIkeotOTFMTPWNf1NH9HfIaMU9PCyuqJL8FntDBQ%3D%3D&attredirects=0NGBaseCU.jpg?attachauth=ANoY7co_8IN1o_xG5gD2rVg5Ie0pjwrG4cPGQgBa7tfaCPAVKLXwuqz0W1xaUnmrPB-WC4mPQNqFFDAFGjJNnI4oG6IAhfs1SCg8f75htvwxTmGIz98bMmCcTgX2M46BECCjMt3QuuoiJOBP8s6M2NJLtMRsWzjCR_uQXNi2SMCfdzxu8t_wRronmx2EQvoUaIEwNXScgVn7dO6cnRRY0wkp5MZ80mP9Wg%3D%3D&attredirects=0

attachment.php?attachmentid=74788&d=1323196904

Just been checking again I'll stick with this layout, it's too difficult to fix the wheels with the other layout.

attachment.php?attachmentid=74787&d=1323196904

Edited by datman

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Not sure what's happening here the pictures disappear when I log off?

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See Thumbnails

post-24509-13387770285_thumb.jpg

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post-24509-133877702856_thumb.jpg

Edited by datman
See Thumbnaols

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I'm looking forward to your completed build datman, this will prove to be an interesting build. Thanks! :)

Edited by Telrad

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I'm looking forward to your completed build Datman, this will prove to be an interesting obs and I look forward to the progress installments. Thanks! :)

Edited by Telrad

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Finally got around to making the base.

First I loosely assembled the base pieces to make sure it would fit into the available space. As you can see it's a tight fit.attachment.php?attachmentid=75197&stc=1&d=1323698905

attachment.php?attachmentid=75198&stc=1&d=1323698875

Now to figure out the angle for the axles. To make the wheels turn as easily as possible they should be at a tangent to the circle they will follow. First find the centre of the circle then align a straight edge to where the axle will be.

attachment.php?attachmentid=75199&stc=1&d=1323698875

attachment.php?attachmentid=75200&stc=1&d=1323698916

Then work out the angle.

It was about 10 degrees

I decided to use a 75mm piece of tube as the axle support working on the theory that If I messed up it only needed another 75mm piece. I also turned some solid PVC to fit inside and glued these in.

I then used a jig to align and glue the elbows.

attachment.php?attachmentid=75201&stc=1&d=1323698916

I also noticed a molding mark on the elbow that could also be used for alignment.

Loose assembled again and added wheels with odd bits and pieces of 12mm just to see if it looks right.

attachment.php?attachmentid=75202&stc=1&d=1323698916

Looks fine.

I have now glued up the Tees amd elbows to the long tube.

Since this observatory will live outdoors I am making axles from black acetal (very low water absorption) and very low friction. Load on each wheel is not much.

post-24509-133877705106_thumb.jpg

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Edited by datman

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The base is assembled and used as a jig for the middle section. Note that because I used a 75mm piece of tube for the axle support I had to fit a piece of tube to match this on the middle section.

attachment.php?attachmentid=75307&stc=1&d=1323871150

The top of the roof should be the same width as each of the base/middle sections so it can be jigged for assemly too.

attachment.php?attachmentid=75308&stc=1&d=1323871175

Note that the elbow offset makes it look odd but it is correct.

attachment.php?attachmentid=75309&stc=1&d=1323871190

I decided to glue the top section together. Once this was done the Base/Middle/Top can all be used as a jig to glue the roof truss sections together.

Oh no I've made the uprights to short! Anyone know a dwarf who needs an observatory?

attachment.php?attachmentid=75310&stc=1&d=1323871202

First full assembly. I've used Tees to stagger the viewing window middle section. This is not finished yet I need to get the optimum height so it does not obstruct the scope at low elevation but also high enough so I don't have to limbo under it. I will wait until the wheels are fitted then do a trial wih the scope inside. A quick try suggests that I might be able to leave 2 of the Tees loose so they act as a hinge and catch.

Maximum height with the wheels fitted is just over 7 feet. I am 5' 10" and I can stand near the sides without my head touching the roof.

attachment.php?attachmentid=75311&stc=1&d=1323871220

What no wheels? After making one axle out of plastic (acetal) I decided it was a bit too bendy for my liking so I will use stainless steel. I have had to order some SS rod. You could use SS bolts but since I have a lathe I am compelled to do it the hard way :-)

Next I have to decide which sections to glue up. As it is some of the joints like to pop out so iI will see how to overcome this. Maybe a spot of the solvent glue on the tube then leave it to dry.

If you fancy having a go I bought my tubing from

Buy Plastic Pipe, Pipe Fittings and MDPE Fittings From ABW Plastics

I used the high pressure 16 bar 32mm

post-24509-133877705707_thumb.jpg

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post-24509-13387770573_thumb.jpg

Edited by datman

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Don't understand what happens with pictures just had a repeat of the whole lot!!!!!

Edited by datman

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Looking really amazing datman. You are obviously a perfectionist.

Thanks for sharing, and I can't wait to see it finished.

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Next I have to decide sections to glue up. As it is some of the joints like to pop out so iI will see how to over come this.

drill and put a nut and bolt through then you retain the ability to dismantle

Edited by m.tweedy

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Hi

Inserting pics is a real pain!!!

Well nuts and bolts would be very time consuming plus I'm looking for something a bit more elegant!

Edited by datman

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Hi Datman,

Framework is looking very impressive. What are you planning to use as the covering?

Hi Stargazer

I've bought some green tarpaulins (Ebays finest) seems a bit thin but when I hold it up to the house lights at night I can't see them. They were pretty cheap so I can always get something thicker if need be. The plan is to permanently cover big sections to make assembly and disassembly as quick as possible.

It will be stored just around the corner from the location shown.

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