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MultumInParvo

A Kentish obsy build

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After much reading and questioning of others, and work and health interrupting things, I am starting work on my home obsy.

The basic requirement is to have a remotely operable DSO imaging rig that I can learn with, due to the fact that I work away from home so much.

I have an NEQ6, an Evostar 80 ED DS pro with an Atik16HR with a starlight express filter wheel, an ST80 with an atik16ic as a guide scope

This led me to consider many threads, for automation noteably those by @Gonzo (Remote unmanned pico observatory) and @Magnus_e (starting summers observatory project, but also standing on the shoulders of most of the build threads.

Even with all of the work others have done, I still have more questions than answers, but then it's been that way for almost 49 years...

A couple of pictures to start with:

2030933043_PierpositionC.thumb.jpg.31ac5c45bfbde18e05a4a3f5d99056dc.jpg

A decent view from 060 to 270, but interrupted by some trees that are not in my control, but my understanding being that I need not worry too much about stuff below 030 I thought to make the walls vs. pier height obscure the lower area to sheild me from light pollution from a local large-ish town in the east-southeast.

20190611_122107.thumb.jpg.37c8eee8bfa882329bb7c89bdf050132.jpg

I have this 3m long 150mm drainage pipe laying around, and 2.1m of workshop wall to work with, but depending on what sage words come in about obscuring the horizon vs. having the telescope parked at a point just below the wall height will tell me how tall the peir should be, but I'm guessing it's the latter and so that would make the pier 1.7m from current ground level.

I plan on this being a 2m square box, only accesible from within the workshop, with a pent roof just above the level of the current roof so I don't need to worry about further guttering, with rails allowing it to slide towards where I am standing, over the top of the existing doors.

My assumption is that 2m is sufficient for any refractor that I might be able to afford, and if I can ever afford anything bigger than an Esprit 150, then I can afford to pay someone to make me a bigger obsy!

I have track and wheels coming from FH Brundle, and various bits to automate the opening and closing and hope to hear back about two brake discs on sale locally for £9.50, so for now I am going to start digging a hole for the pier and gathering posts, OSB and other timber in readiness.

All input is welcome, and in fact my favourite "Clerk of Works" has already been advising me to sing whilst I build:

1490016847_ClerkofWorks2.jpg.0a1c3190779034a2ed90139207878fa6.jpg

 

All the best,

Ian

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Posted (edited)

And we've never been seen in the same place at the same time...

Have you started a build yet or just gathering info? 

Edited by MultumInParvo

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Glad to see the build plan has moved along Ian,
Hope the ED80 gets to be part of it.

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End of day 1, hole is now 700x700 and 450 deep, thinking I need to get down another 250, but wonder if this is sufficient still, but I'd rather it be overkill than keel over so will see how my back feels in the morning...

First bit of good luck. I found two brake discs locally that fit beatifully in my 150mm tube for only £9.50 (search for "Brembo 08-4962-10" as they fit all sorts of vehicles), bit of surface rust but will come up nicely when painted:

2093133727_Discbrake.jpg.df6beb6ffc688692c82e1b1b93bf43f4.jpg

Thanks to @mhard26339 and his thread for this idea - New observatory in Norfolk

An early start tomorrow preparing these and some more items like the shuttering for the hole, and if the rain clears up early I'll continue with the digging, but for now, I've Adze enough:

20190611_204743.thumb.jpg.1ee2aad36b43ef2bb79c7fbafbcf7700.jpg

Sorry, couldn't resist that one 😁

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I think a 700mm cube is probably more than sufficient.  I reckon 1.7m might be a bit taller than really necessary for the pier though.   Mine aren't much higher than the standard NEQ6 tripod.

Which way is the roof going to roll off?  Away from the shed at a right angle?

James

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Hi James.

My back thanks you for that in advance...

Yes, if you were looking as per my first photo, it will slide off to the right, and will be at a height such that it falls back onto he existing roof behind with a decent overlap to help avoid rain or snow driven by the north wind.

I think I picked up from your build (or could have been @Astrokev) that I need to deal with the possibility of water leaking in around the rails, not sure if I will have the same issue as I am using some spare Onduline I have laying around rather than EDPM, but was going to ask you about that.

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I think my temptation in that case would be to lower the pier and wall height and then have sides on the rolling roof section, though I guess that might risk compromising your view to the West?  Perhaps it depends how high the sides of the roof were.

From memory I think my piers are about 850mm above floor height, and my walls are definitely 1500mm.  On top of the piers there is another 30mm or so of pier adapter and the mount.  With the ED80/NEQ6 I'm sure I can still see Jupiter at its current elevation.  Or would be able to but for the cloud.

What might be worth doing is to set up some string or bits of timber in the right position at what you think will be the finished rail height and put the tripod and mount in the pier position and see how much it needs raising to get the clearance you need.  I put a length of batten in the dovetail so I could swing it about on the mount and check sight lines.

As regards water leaking in around the rails, it can form small "puddles" if the rails aren't 100% level and then find a way to run in either alongside or under the rail.  Given a suitable wind it can probably blow in even if the rails are level.  When I re-fitted my rails at one point, I blocked the channel underneath with some silicone sealant to stop water running down the inside and also put a blob of sealant into each screw hole when I put the coach screws back in to hold it down so water couldn't track through the holes.  I also did as Kev has done and made a little "wall" out of layers of EPDM to block the gap between the side of my warm room roof and the rail, though that could be done may other ways.  Even last night when the rain was, frankly, torrential, it has remained dry inside.

James

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Thanks for that James.  Being so green, it's hard to know what's useful or not without input from the experienced.

My thought of not showing the lower 20-30 degrees above the horizon was down to some input I got last year, and also thinking that having protection from wind would be a good thing, but I knew there had to be a good reason why I didn't see this kind of build...

I'll do as you suggest and set up  the tripod and mount with some timber for sighting, and build a basic framework and post some pics.

Ian

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Posted (edited)
15 hours ago, MultumInParvo said:

And we've never been seen in the same place at the same time...

Have you started a build yet or just gathering info? 

Not as yet...still very much in the planning stage.. I've sourced something for the pier, sort of found out what size it needs to be and a friend has given me some info on his build

Where abouts are you in Kent?

Frame to gauge size

received_394303321166535.jpeg

Edited by newbie alert
Added info

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Good luck with the planning, it was a critical element for me, and took time to muill over the best way forward.

I have had nothing but good advice and helpful comments from the members, and I'd highly recommend posting a new thread to garner opinions and encouragement for your build.

I'll keep posting links to the threads that have inspired my decisions so hopefully this will assist in your planning in some small way.

All the best,

Ian

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One question I have is about vapour barriers and insulation - what are the pros and cons?

I don't see condensation in my workshop and the obsy will have a similar construction - concrete/paving slab floor, timber frame, feather edge clad OSB walls and roof, with roof topped with Onduline. 

There is plenty of ventilation in the workshop, so this may be a factor, and I was assuming I would adequately ventilate the obsy so that it was at roughly the same temp as outside.

Love some input on this before I put the OSB up this weekend...

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I think vapour barrier is a good idea because it prevents rainwater (or snow!) being driven into places it can get at the structure of the building.

In your case I don't think I'd bother with insulation though.  I only have it around my warm room.  The rest of the walls are uninsulated.  The only place I'm reconsidering is actually the roof, which does transmit a lot of heat into the scope room on those two sunny days we get each year.  I've not decided yet, but I may put some insulation on the inside of the roof just to limit the heat transferred inside.

James

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Any suggestions on the type of barrier?

Lots of different ones like Tyvek, foil, and others like DPM, of which I have a fairly big sheet that would cover the obsy walls.

It has a few nail holes in it as it was used in an emergency covering job last year when I was extending my workshop, but assuming that this is belt and braces behind the OSB, so may be ok?

I think that insulating the roof is a good idea, may get some 50mm celotex, I need some for cutting sheet materials on anyway, last one was so well used with all the 8x4 sheets I have ripped in the last 6 years that it barely serves it's purpose now.

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10 minutes ago, JamesF said:

... The only place I'm reconsidering is actually the roof, which does transmit a lot of heat into the scope room on those two sunny days we get each year.  I've not decided yet, but I may put some insulation on the inside of the roof just to limit the heat transferred inside.

James

Roof definitely.

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Some measurements from my observatory:

From the floor to the bottom edge of the mount (excluding the inner flange) is 850mm.  To the point where the RA and DEC axes "cross" on the NEQ6 is about 1200mm.  The tops of the walls are 1500mm above the floor.  The piers area 900mm from the nearest wall.  I think that means that if the DEC axis is horizontal then the telescope can "see" anything over 20 degrees.

James

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I used Tyvek for the barrier.

James

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2 Metre square scope room
Drain pipe pier  (mine's 200mm)
170cm pier height
70 x 70 x 80cm deep pier hole

Track and wheels from FH Brundle
NEQ6 on top of brake disks
Southern view partly obscured by trees
Pent roof with no guttering

Have you been in my garden? 🤣🤣

https://stargazerslounge.com/topic/296023-observatory-in-kirkintilloch

Definitely use vapour barrier as you build as it's almost impossible to install afterwards.  I did the whole obsy just in case I later wanted to insulate and add internal cladding to the scope room.   I've not insulated my rolling roof and it does get really hot in the midday sun. EPDM reaches 60c and transmits plenty of heat into the obsy. However, I left a 5mm gap between roof and walls to allow plenty of ventilation so excess heat (or damp) has not been a problem.

Once you've worked out how many sockets you want just double it!  You'll be surprised how many additional things eventually need one.   Don't forget the hoover, you'll want to clean the place occasionally.

Have fun building it and using it.

 

 

 

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Tyvek is here, enough to cover my whole workshop before I put up the featheredge on the remaining threee sides...

Celotex is to be collected tonight.

Now it's stopped raining I'll do my sighting @JamesF

@LongJohn54 - Great minds are clearly thinking alike, either that or we both scoured the same forum and stood on the shoulders of giants, but I'm sticking with the former. 😎

I plan to keep anything mains related out of the obsy as it attaches to the workshop, and the door into it will be from in there, so now I just need to plan for a pipe to bring USB and 12v back to the workshop where I have power and cat5e gigabit connection.

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Posted (edited)

On the wall/peir height question, I have =been doing some thinking and measuring.

The first challenge is that I need to position the rear roof track at about 2.2m to clear the workshop door:

20190613_134446.thumb.jpg.f03a621137acac5c212634fe5392322e.jpg

And I wonder if having the walls lower than anticipated would cause wight issues for the automated ROR design I intend to follow:

If I were to position the walls as per my calcs (ground not levelled so only roughly done),  based on a tripod height of about 1280mm, and a demand of at least down to 20 degrees above the horizon I could have 1800mm walls:

20190613_134516.thumb.jpg.e4cb01d68309c561daa6b9cc864f4e94.jpg

But the eastern wall would need to flap down to 1500mm, but I could do that as part of the automated opening I think:

20190613_134539.thumb.jpg.28de5614bd299bfcefbb23d4eda52b8a.jpg

Not worried about the wes round to north as it would need a height of 2m+ to boscure the view:

20190613_151629.thumb.jpg.b932a0154f3f1c7228e6ab2a12b20c6a.jpg

That leaves me with a flat roof and 800mm of wall at the front and 600 to 800 at the sides to replicate the fall of the workshop roof, so hopefully not massively different in weight than just the flat roof in the thread.

I think a 1300mm pier of 150mm diameter, reinforced with an internal steel lintel (https://www.wickes.co.uk/IG-Ltd-Internal-Lintel---1200mm/p/220067 x 2, joined to create a single central piece of steel total length of 2.2m), with the option of a couple of 2m lengths of 20mm angle iron sounds ok, but interested in any issues others can think of.

 

Now back to emptying the swimming pool that the rain has created so I can get back to trying to dig out 200mm of compacted clay:

20190613_134544.jpg

 

Edited by MultumInParvo

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Lots of prep work now done, inclcuding making the door swing inwards, which took a surprising amount of time and effort, but finally levelled the last of the concrete at 9:15 tonight...

20190617_211404.thumb.jpg.9117f16186878ee109405c7d573dc3f2.jpg

And not too far off the bubble:

20190617_211415.thumb.jpg.ba4004438cd6a717ca39f0d0a0c9b6da.jpg

I had quite forgotten how bloody hard it is as a solo job even with a mixer, and with 48 bags of ballast and cement in there I'm pretty sure I'm going to ache tomorrow...

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Great work.. reminds me of when I was building mine.

 

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Great work. I am planning an obsy build for next year and I ‘thought’ I had had an original thought..... there you go, brake disc, obviously not.

I got mine from my friendly Renault garage for nothing (traffic van front discs) used obviously, just need a little grinding and a coat of paint. Ventilated as well helps with mount calibration 😂

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