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5 weeks and counting, too many jobs to do..!

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#1 Neil

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Posted 07 October 2006 - 03:01 AM

Well I finally did it.
I have been planning this for about a year, mainly saving up the required funds and managing to persuade the 'Financial controller' about the merits of a new observatory.

I have ordered a 9 foot full height observatory from Pulsar Domes here in the UK. Now I just have to:
1) Clear the ground.
2) Chop down an apple tree.
3) Lay the foundations.
4) Sort out the electrics.
5) and no doubt a million other jobs I haven't even considered.

Foundation wil be 10 foot square by 8 inches deep concrete, reinforced etc.
Pier will be homemade (already done....I'll post pictures later) with a Paramount ME on top.
The metal Pier will be bolted directly to the floor using 4 25mm concrete bolts.
The observatory floor will be bolted directly to the concrete using 6 HUGE concrete bolts.
Electricity will be run from the fuse box out of the garage and underneath block paving and under a channel about 18 inches deep. I am using waste conduit about one and a half inches and also going with armoured cable to supply the electricity.
I have quite a long garden about 80 to 90 feet so I can look forward to loads of blisters and backache...:)

If anyone would like to comment on my up and coming adventure then please do, I'm sure I've missed something and your help and guidance would be most welcome.

Thanks for reading.
Cheers,
Neil.

#2 nytecam

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Posted 07 October 2006 - 05:00 AM

Well I finally did it....snip...Foundation wil be 10 foot square by 8 inches deep concrete, reinforced etc. The metal Pier will be bolted directly to the floor using 4 25mm concrete bolts. The observatory floor will be bolted directly to the concrete using 6 HUGE concrete bolts.
Electricity will be run from the fuse box out of the garage and underneath block paving and under a channel about 18 inches deep. I am using waste conduit about one and a half inches and also going with armoured cable to supply the electricity. If anyone would like to comment.. snip.. be most welcome.Cheers,Neil.


Hello Neil - just a few hopefully helpful points - is the base the same shape as the dome base ? If circular the base should be likewise without overhang. Your concrete base seems overkill - you need it thicker at the edge say 9-12" deep into the soil x a spade width say 8" and it should project ~4" min above the ground all round to stop ground water getting inside! Mastic seals alone don't work! 4" unreinforced base concrete is adequate but again thicked considerably around the pier. I'd go a min 2'x2'x3' deep and you should isolate this pier concrete with polystyrene so there's no physical contact with the base slab. I'd further recommend a old carpet over the finished floor to 'catch' falling eyepieces and stop vibration from you moving around being transferred to the pier and scope. Good luck in your project. :rainbow: My site below has more pointers :smirk:

#3 GordonCopestake

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Posted 07 October 2006 - 05:31 AM

Congraulations Neil! It will be one of your best astro purchases of all time hehe.

Make sure you take lots of photos before and after and during construction to share with us here. Theres nothing better than seeing a great new obs being built!

Just one point, make sure that the waste conduit you are using to run your power in is black not brown. You dont want to be digging it (or someone else digging it up) in the future and think it's a water pipe. Black is used to denote electricity. (yellow gas, green information, blue clean water, brown waste water etc etc)

I would also echo Nytecam about isolating your pier from your floor. An inch gap in the concrete slab around your pier filled with expanding foam should do the trick.

#4 Neil

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Posted 07 October 2006 - 11:47 AM

Hello Neil - just a few hopefully helpful points - is the base the same shape as the dome base ?


No my base will be a 10 foot by 10 foot base whilst the observatory will be a 9 foot circle.

If circular the base should be likewise without overhang. Your concrete base seems overkill - you need it thicker at the edge say 9-12" deep into the soil x a spade width say 8" and it should project ~4" min above the ground all round to stop ground water getting inside!



The base will be about 4 inches above the ground. I'm planning on using some sort of hardcore and 'wacking' it down to provide a good stable footing.

I'd go a min 2'x2'x3' deep and you should isolate this pier concrete with polystyrene so there's no physical contact with the base slab.



Why is this necessary? I'm thinking 8 inches across the whole floor should be sufficient. Surely the thickness of concrete and solidity of the pier and the mount will provide a solid enough base to view and image through???

I'd further recommend a old carpet over the finished floor to 'catch' falling eyepieces and stop vibration from you moving around being transferred to the pier and scope.


Now that is an excellent idea, and will probably save a few mishaps that can happen in the dark.

Good luck in your project. :rainbow: My site below has more pointers :smirk:


Many thanks for the suggestions nytecam, keep 'em coming people.... ;)
Regards,
Neil.

#5 Neil

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Posted 07 October 2006 - 11:52 AM

Congraulations Neil! It will be one of your best astro purchases of all time hehe.

Make sure you take lots of photos before and after and during construction to share with us here. Theres nothing better than seeing a great new obs being built!


Cheers Gordon, I'll post some piccies of the homemade pier and my lovely Paramount thats waiting in the garage. I'll also try and do a history of the project as I go.

Just one point, make sure that the waste conduit you are using to run your power in is black not brown. You dont want to be digging it (or someone else digging it up) in the future and think it's a water pipe. Black is used to denote electricity. (yellow gas, green information, blue clean water, brown waste water etc etc)


Brilliant idea Gordon, I would have never have thought of that, cheers.... ;)

Thanks for the suggestions guys.
Regards,
Neil.

#6 Neil

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Posted 07 October 2006 - 11:57 AM

Heres a few pictures of the dome and observatory that I have chosen.

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#7 Neil

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Posted 07 October 2006 - 11:58 AM

And another

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#8 Michael Morris

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Posted 07 October 2006 - 12:22 PM

Two points on the conduit for your electrics.

1) - Anything with joints in it can leak. Your using armoured cable and this should be waterproof, however I'm not sure if it will remain waterproof if the pipe fills with water and the cable become pretty much permanently immersed. I used 25mm blue waterpipe for my conduit. It has COMPLETELY waterproof compression joint elbows at each end = no possible leaks into the pipe. If your really fussed about the colour (see warning tape section below), agricultural irrigation pipe is the same stuff and is black. I shopped around lots and found that if you need more than 20 metres of blue 25mm pipe, the cheapest way to buy it is to buy 50 metres of it from Screwfix.com - just £18.99 for the pipe and £2.99 for each joint.

2) - You will need to put some yellow cable warning tape at least 10cm above the conduit. You can get a 50 metre roll of it from B&Q for about £4.

Be aware that, to comply with building regulations, the electrics should be signed off by either a suitably qualified electrician or by your local council building control department ....... strictly speaking.

Let me tell you, building an observatory is a lot of work, I'd start work sooner rather then later. If fact, what are you doing lazing about reading this, get back to work NOW!

#9 GordonCopestake

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Posted 07 October 2006 - 12:24 PM

I didn't know about the warning tape Mike, good tip.

#10 Neil

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Posted 07 October 2006 - 12:39 PM

Two points on the conduit for your electrics.

1) - Anything with joints in it can leak. Your using armoured cable and this should be waterproof, however I'm not sure if it will remain waterproof if the pipe fills with water and the cable become pretty much permanently immersed.


I have been informed that it would be water tight by an electrician. Hopefully this won't have to be tested as I plan on using 6 feet lengths of waste pipe with inline connected that are also water tight.

2) - You will need to put some yellow cable warning tape at least 10cm above the conduit. You can get a 50 metre roll of it from B&Q for about £4.


Good idea Michael, not too expensive either!

Be aware that, to comply with building regulations, the electrics should be signed off by either a suitably qualified electrician or by your local council building control department ....... strictly speaking.


No problem, it will be.

Let me tell you, building an observatory is a lot of work, I'd start work sooner rather then later. If fact, what are you doing lazing about reading this, get back to work NOW!


:lol: :lol: :lol: :lol: :lol:
Well I break ground tomorrow, and will hopefully be ready for my friend, who's helping with the concrete next weekend hopefully.
I realise its a big undertaking Michael, but I'm hopefully going to enjoy it as well, or at least try too!!!

Thanks for the tips.
Regards,
Neil.

#11 nytecam

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Posted 07 October 2006 - 04:08 PM

Why is this necessary? I'm thinking 8 inches across the whole floor should be sufficient. Surely the thickness of concrete and solidity of the pier and the mount will provide a solid enough base to view and image through???


Sorry Neil - I was under the impression you were seeking advise :o A telescope = seismograph - when your project's complete put a webcam in your scope [not quoted] and watch on a monitor as you walk around the observatory or near the scope :smirk:

#12 Neil

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Posted 07 October 2006 - 04:53 PM

Sorry Neil - I was under the impression you were seeking advise :o A telescope = seismograph - when your project's complete put a webcam in your scope [not quoted] and watch on a monitor as you walk around the observatory or near the scope :smirk:


Yes, I would like friendly advice Nytecam, and welcome your comments as you have been there and done it.
I didn't realise that not having a decent platform for the pier and scope would be that bad??? It really would shake that much if you walked around the scope??? I don't intend to 'break dance' around it.

Looks like I'll factor in a couple of more days digging then.....oh joy...;)
Thanks for the advice, so 2 feet by 2 feet by 3 feet deep would be sufficient to isolate the pier?

Regards,
Neil.

#13 SleepIsWrong

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Posted 07 October 2006 - 08:43 PM

Actually my pier is three feet deep - about 16 inches square, and isolated from the building. When I rotate the dome I can see the stars wiggle just a little. To avoid that during imaging I must rotate the dome slowly. Its surprising what you'll be able to see, vibration-wise. There is a freight train track a few miles from me and when a train is running on that track I can see the autoguiding errors grow and can measure the fwhm difference in my star images. Its not a lot, mind you, but does increase the rms guiding/tracking errors from my typlical 0.8 arcsec to around 1.4 arcsec. I can't imagine how much it would vibrate if I hadn't done what I could to isolate the pier from the building. Not that that does anything for the train rumble.

Mike

#14 NeoDinian

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Posted 07 October 2006 - 11:33 PM

Heheh.. Not that it will effect me, but I live just about 6 blocks from a Rock quarry. 3 days a week, at about 10am, you feel the house shake a bit... Thats their BLASTING schedule! REAL awkward feeling when we first moved in. "What was that!!!". At least at night they don't blast. :)

#15 GordonCopestake

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Posted 08 October 2006 - 03:07 AM

Neil, personally I would build your pier foundations first (use the 3'x3'x3' box as a starter) then leave a 1" gap around the pier foundation and lay your dome floor foundation. Fill the gap between the 2 foundations with expanding foam or polystyrene. This means your scope will be mostly isolated from the floor.

A good example of this (not quite the same but you get the idea), i recently had some decking installed in my garden. Looked very nice and i was quite pleased. I was using the new deck as a level platform for my telescope but at high magnification I couldn't get the view steady. The view kept bouncing slightly. I held myself completly still but just couldn't work out what this little bounce was. Turns out I was quite happy for the little bounce as it meant my heart was still beating! I joke not.

I now setup on my lawn rather than my deck

#16 Michael Morris

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Posted 08 October 2006 - 06:25 AM

Neil
My pier base is a hole 700mm x 700mm x 800mm deep. My shed is mounted on a wooden frame which sits on nine concrete slabs, each laid on a 2 inch deep bed of sand. Each slab is at least 600mm from the edge of the pier concrete. The floor frame frame is secured to the ground by four wooden posts bolted to the inside of the frame. These four short wooden posts are embedded in concrete at the four corners of the observatory, well away from the pier. The wooden floor of the observatory does not touch the pier, with the gap being filled with some foam insulation.


I can have my webcam set up on the back of my 8" LX200 and walk around the observatory. I can see no movement of the image at all. I'm sure if I started jumping up and down the webcam probabaly would pick it up a bit. It helps a lot that I have loose, free draining sandy soil, so vibrations do not propagate well though it.

By the way, you can see details of this and the use of cable warning tape (see earlier in this thread) on the construction pages of my obsrevatory website - link below.

WEBSITES DOWN AT THE MOMENT (SUNDAY 8TH OCTOBER - INVESTIGATING!)

#17 nytecam

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Posted 09 October 2006 - 05:42 AM

Hi Neil – some interesting discussion coming through here :smirk:

My comments, as an architect, would be largely overkill on this forum and anyway building an observatory is great fun and it of little consequence if it wobbles or leaks rain a little as importantly nobody is going to live in it! However when I saw you’d not dug the first sod and were going to use a Paramount I realised you’re seriously into real imaging not just stargazing and thought I could be of help.

The importance of the isolated telescope pier is paramount [pun intended] and on reflection the fibreglass dome is lightweight in building terms and could adequately be supported on a ring of raised and bedded bricks with hardcore + concrete topping up to the pier base. Remember every sod of earth removed must be replaced with concrete [or comparable density material] and it can get very labour intensive without prior planning. :rainbow: This is what I meant about matching base to observatory shape. :smirk:

#18 Neil

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Posted 09 October 2006 - 12:55 PM

By the way, you can see details of this and the use of cable warning tape (see earlier in this thread) on the construction pages of my obsrevatory website - link below.

WEBSITES DOWN AT THE MOMENT (SUNDAY 8TH OCTOBER - INVESTIGATING!)


Thanks for the heads up Michael, I'll certainly check out your info once the website is back online, cheers.
Neil.

#19 Neil

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Posted 09 October 2006 - 12:57 PM

Neil, personally I would build your pier foundations first (use the 3'x3'x3' box as a starter) then leave a 1" gap around the pier foundation and lay your dome floor foundation. Fill the gap between the 2 foundations with expanding foam or polystyrene. This means your scope will be mostly isolated from the floor.


A good idea Gordon and one that I will use. I have seen the error of my ways and have dug out for my pier, so I am on solid ground (pun intended) from now on.
Cheers,
Neil.

#20 Neil

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Posted 09 October 2006 - 01:09 PM

Ok, this view is where I am going to put my observatory.
More or less bang in the middle of all the stepping stones. It will be just over 6 feet from the bottom fence and 6 feet from the neighbours hawthorn hedge.

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#21 Neil

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Posted 09 October 2006 - 01:14 PM

These are a couple of pictures of the hole for the pier I have just dug.
It is approximately 24 inches x 24 inches by 24 inches. I can't go any deeper as I have hit bedrock.... :grin:

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#22 Neil

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Posted 09 October 2006 - 01:20 PM

And another one.

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#23 MichaelW

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Posted 09 October 2006 - 01:53 PM

Drill some holes into the bedrock then drill and epoxy some rebar in there and you wil have one very solid foundation for the pier!

#24 Neil

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Posted 09 October 2006 - 02:30 PM

Drill some holes into the bedrock then drill and epoxy some rebar in there and you wil have one very solid foundation for the pier!


Excellent idea, is rebar normal round metal bar?

Cheers,Neil.

#25 Neil

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Posted 09 October 2006 - 02:43 PM

Ok I've found that rebar is
"Rebar is common steel reinforcing bar, an important component of reinforced concrete and reinforced masonry structures. It is usually formed from mild steel, and is given ridges for better frictional adhesion to the concrete"

What size do you recommend? As it comes in various sizes.

Cheers,
Neil.


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