New Sliding Roof Mini Garden Observatory Build

[Domain105]

Hello all,

After months of trawling through SGL for ideas and inspiration, I've decided to bite the bullet and build a mini garden observatory for my 150PDS on a HEQ5. So many of the builds and threads on here have been brilliant and a testament to this communities ingenuity and skills beyond astronomy! 

I was fed up with the setup and take down time for my astro setup, especially when my kit normally lived in my office on the 2nd floor.  I wanted to build something small as my garden is not very big and I could only get planning permission from the wife if I kept it as small as possible.  I did spend a lot of time thinking about how to slide the roof as a lot of the designs here are for sliding roofs that are on wheels / rails. this design is really good but it also meant that I would need additional structures in the garden for the roof to slide on to and that would take up more space. In the end I decided to go for heavy duty drawer slides as my obsy was only going to be as big as the scope 'swing area'. I'll update on this thread as I progress but please bear in mind that I have very limited DIY skills or tools so I am going to take things a little slow and my posts will be filled with mistakes but I guess its all part of the learning process. 

Part 1 - the HEQ5 mount

My first task was to build a pier mount for my HEQ5. For this I used some brake disks after numerous examples posted here. The exact models where TRW Brake Discs Pair Front DF1608 3322937807697 for about £20 on ebay. They seem to fir the HEQ5 perfectly. It was akiller to drill the 16mm holes in them but after a few days and some really shaky arms from the drill vibrations, they were done! Then came a selection of M16 threaded bars to hold everything together and a custom plate for the bottom and some M12 bolds for added strength as these would also go into the concrete pier. 

The idea was to fill a 200mm wide plastic tube with concrete and place this inside.

 

 

 

[Domain105]

Part 2 - Pier build

This was quite challenging as I had never mixed concrete before nor had I a real clue on how much I would need and I was also worried about vibrations and the fact that my ground is mostly clay. I started off digging a hole approx 800 x 800mm wide and about the same deep. I added some rebars to add strength to the pier and was still worried on stable it would be. I read alot about ensuring the concrete in the pier is in the same block as the ground concrete (so that the pier plastic tube doesn't split the two bits of concrete.  With the hole dug, I placed my 200mm wide plastic tubing (I got from ebay into the hole and filled everything with concrete. I mixed in a large bucket and poured in. I did consider hiring a mixed but decided to give it a shot manually. 

With the tubing filled with concrete, I placed my pier on top, pointing north. and left it a few days to settle.  Once dry, I placed my HEQ5 and 150PDS on the pier to do a testing imaging run to check for vibrations but it was rock solid 🙂 I was so glad as that was my main worry. I did jump around on the group while imaging and it remained solid. I also tried gently knocking the pier and it was still ok so I was really pleased!

I measured the pier height before I set it in concrete so that the I had a good view of Polaris from the telescope and guide scope (sharpcap polar align). Due North is directly towards the fence in the pics.  

Now with the pier done, next challenge was to build the actual obsy.  😬

 

[Domain105]

Part 3 - Obsy Frame Build

Now I really don't have much of a clue about wood work as I am an IT Architect by trade so I asked around to see if anyone would build it for me but the costs were really high and as I still didn't have a final design in mind, I opted to build it my self. time will tell if this was a huge mistake!!.

As I was going for as small as possible, I wanted the obsy to be about as high as the scope laying horizontally on the HEQ5. I swung the mount and scope in all directions possible to determine the dimensions of the inside of the obsy and it worked out roughly 1400mm wide, 1300mm deep and 1250mm high. My main reason for the build was the setup time for imaging so even with a small setup, all I had to do was open the roof and I was 90% of the way there. the sliding roof really caused me a lot of stress. I thought about building using plastic and have a flip lid but the strain on the hinges was another big concern. Thats were I saw an article on heavy duty drawer slides that could hold 100KGs+ fully extended. I bough the following:

AOLISHENG 1 Pair(2-Pack) Heavy Duty Drawer Runner 1400mm Ball Bearing Full Extension Drawer Slides with a Load Capacity of up to 150 Kg : Amazon.co.uk: DIY & Tools

they are really expensive but I really hoped they could deal with the load and last a while

So using a load of 4x4 and 4x2 timber, I managed to get the frame sorted. Sticking the drawer slides was a mammoth task. I screwed them to an inch of their lives to ensure the loads does not rip the railing from the wood. 

I also wanted a slightly slanted roof so water does not stay on top and also so I can add solar panels in the future. The slant points directly due south. 

With the roof frame assembled, my attention turned to the flooring. I still had grass sticking out the bottom of the frame!. I dug this up and placed a waterproof membrane along the flooring and poured in some more concrete with the frame acting as a mould. As my concrete levelling skills were non existent, I finished off with some self leveling concrete for a more even finish.

Next step is to complete the roof by panelling with OSB3 boards and felting it before I concentrate on the sides and door and flooring again.

Btw, with the roof framing in place, the drawer slides are still working beautifully and are very smooth indeed. Lets see how they feel with the full weight of the roof 🙂

In the next part, I will be completing the roof. 

[GordonD]

This looks brilliant! Well done. 

Really interested to see how it works when finished. You might inspire me to finally get on with one myself after thinking about it for years.

[Domain105]

Thank you for the kind words. I'm usually very ordered and plan everything to the finest detail. This time I'm sort of making it up as I'm going. I couldn't have got this far without this community! 

I've been thinking about building one for a while but thought I couldn't due to my limited space. 

[Petrol]

That looks great! Mucho impressed

[M40]

Superb 👌 I have seen runners used once before, phenomenal idea 👍 well looking forward to see how it progresses.

[david_taurus83]

That looks great! Will definitely be looking to this thread if I get the chance to do it for myself! I like the heavy duty runners idea! Will you need to keep them regularly greased due to outdoor conditions?

[Domain105]

Yes regular maintenance is going to be needed but I'm not sure how often I'll need to do it. I'll also need to look into the most suitable grease for our door use. 

[Domain105]

Thank you everyone for the comments and likes. I've got as far as completing the roof so will post another update soon. 

[teoria_del_big_bang]

15 hours ago, GordonD said:

This looks brilliant! Well done. 

Really interested to see how it works when finished. You might inspire me to finally get on with one myself after thinking about it for years.

Exactly the same with me 🙂 

Steve

[ScouseSpaceCadet]

This is a solution I may get away with... I'm looking forward to the finished result. Thanks for posting.

Edited July 12, 2021 by ScouseSpaceCadet

[teoria_del_big_bang]

Looks great - I really am looking forward to the finished product.

As a retired Engineer if you do decide to grease the runners I would think the type of grease is not that important.
The runners are not under any pressure or workload so it is just a matter of protecting from the elements..

My personal thoughts are that maybe packing with grease may make things worse as if the wind then blows any grit or dirt under there then it will just allow all that dirt and grit to stay on the balls and runners and promote wear rather than prevent it. So my personal preference would be to try spraying with something that dries, maybe even a silicone spray or some sort of dry PTFE lube like THIS

When open all being well the weather will be pretty dry, so any protection is just to stop any rust or corrosion starting.
When closed, from the pictures the runners look pretty much covered up so will be quite well protected from a massive ingress of water, so again the protection is just to stop the rust  and corrosion start and on top of that just to add some lubrication so i think the dry lube may work well.
Maybe, a strip of rubber attached to the underside of the sliding lid at either side that just slightly rubs against the sides of the fixed bottom, what I would call sealing strips,  might add some extra cover for them (if that makes any sense - I know what I mean but difficult to explain).

There is also Lithium Grease which maybe a bit OTT for this application and I am not sure how dry it ends up but maybe worth a thought if the dry lube does not give enough protection.

Steve

Edited July 12, 2021 by teoria_del_big_bang

[Domain105]

Thanks for the info about the grease. I'll try that instead of killing it with grease as I was planning on doing 😄.  I will add some sort of flexible strip to stop water ingress over the slide bars but I have added some extra trim to neaten it and it is less exposed than before and also the felt I added has helped narrow the gap. I did want to leave some gap to allow moisture and hot air to escape but am balancing that with water ingress.

 

[teoria_del_big_bang]

4 minutes ago, Domain105 said:

Thanks for the info about the grease. I'll try that instead of killing it with grease as I was planning on doing 😄.  I will add some sort of flexible strip to stop water ingress over the slide bars but I have added some extra trim to neaten it and it is less exposed than before and also the felt I added has helped narrow the gap. I did want to leave some gap to allow moisture and hot air to escape but am balancing that with water ingress.

 

Always tricky as outdoors there will always be plenty of moisture in the air.
A lot may just come down to the quality of the runners and what material they are made from. Sometimes some products just rust or pit whatever you try and do but obviously any added spray or grease will help prevent this and slow it down.
Also maybe I am worried too much about any ingress of grit and dirt. In the end it is not as if you are constantly moving the lid back and forth all the time, so even a bit of muck in there may not really affect anything and protecting from corrosion is far more important. 
Yes it is great to move something with great ease and feeling it is oh so smooth, it is very satisfying, but in the end if it feels a bit notchy over the years due to a bit of dirt but still opens and closes easily then does it really matter ? --- probably not 🙂 

Steve

[Domain105]

Part 4 - Finishing the Roof

So with the roof frame built, the next step was to finish the roof. I used 9mm OSB3 boards, felt adhesive and some heavy duty roofing felt (all from Wickes) to complete the roof. I added some trim to neaten the felt ends and a shed load of nails to tack the felt in. One lesson learned was not use use a £20 jigsaw from Amazon to cut the OSB board. Even when I used a clamped wooden strip to guide the jigsaw, it was so wonky. the blade kept wanting to turn and go where it wanted. I tried going slow, not putting too much pressure on it but it still was no good. Maybe a reflection of my jig saw skills than the saw it self?

The roof now seems water tight and looks better than I thought it would. 

I have received a caution for the damage to the grass next to the obsy 😄 Looks like I'll add some grass seed / feed costs to my overall expenses.

Another lesson learned was that I should have left a bit more of a gap between the fence and the obsy. Luckily, my neighbour is a lovely chap so lifted the fence panels so I can easily work on the obsy from his garden. He even trimmed his little tree just on the side of the fence for me in case it came in the way of my viewing. Now I have an fully unobstructed view of Polaris from the obsy.

My other neighbour is a retired physics teacher who is also following with great interest.

Next step will be to finish the floor (have got a large OSB3 11mm board for that) To match the style of the existing shed, I'm going to use T&G cladding. I didn't realised how expensive it is but have found somewhere that does 19mm T&G treated Pine cladding for £10 for 4.2m. Need to also work out how many I will need. I've also am planning a mini door on the side so I can go in to the obsy should I need to.

 

[Domain105]

Sorry forgot to add... All timber is either bought pressure treated or I have stained it with woodstain (2.5L for £13) from Wickes. Light Oak.

Now the roof has it's full weight, the slides are still running super smooth with now issues so that's a result!

This is as far as I have currently got. I wanted to post as I progressed but didn't get the chance.  Hopefully with the weather improving next week, I will be able to continue.

Edited July 12, 2021 by Domain105

[teoria_del_big_bang]

Looking spot on  🙂 

Steve

[Domain105]

2 minutes ago, teoria_del_big_bang said:

Looking spot on  🙂 

Steve

Thank you. Don't mind the wonky felt nails. It unique not perfect 🤣

[teoria_del_big_bang]

4 minutes ago, Domain105 said:

. Don't mind the wonky felt nails. It unique not perfect 🤣

Ha Ha, Never noticed actually, functionality wise makes no difference but I think we all have some form of OCD.

Steve

[AstroMuni]

16 minutes ago, Domain105 said:

Now the roof has it's full weight, the slides are still running super smooth with now issues so that's a result!

Looks great! I love it If you are worried about the load on the drawer runners, you could consider adding a pair of feet on the extreme right with castors on them to support the roof when its open. Just my 2 bits of thought.

[Domain105]

4 minutes ago, AstroMuni said:

Looks great! I love it If you are worried about the load on the drawer runners, you could consider adding a pair of feet on the extreme right with castors on them to support the roof when its open. Just my 2 bits of thought.

Hi, thanks for that suggestion. It is my fall back if the weight seems too much. I was worried when I started but as the moment, the slides are working really well. Maybe in the future as things get a bit tired and worn, I'll do that.

[AstroMuni]

5 minutes ago, Domain105 said:

Maybe in the future as things get a bit tired and worn, I'll do that.

If & when that happens (lets hope its in the far distant future ) I would suggest you put the roof on 4 legs and put a track on the ground.

[Domain105]

To work out the internal dimensions of the mini obsy, I swung the telescope around with the camera and everything loaded as per normal on the 150PDS and the pier and HEQ5 and got the following measurements. The actual obsy is slightly bigger to accommodate for some room for new purchases such as a dedicated camera and my DIY Peltier DSLR cooler. 

[Domain105]

1 minute ago, AstroMuni said:

If & when that happens (lets hope its in the far distant future ) I would suggest you put the roof on 4 legs and put a track on the ground.

Thank you. Yes exactly my thoughts. There should be nothing in my design so far that should stop me from doing that in the future should I need to. I'm still hoping the rails do their job but you never know!