Obs Project

[peter_4059]

Having recently discovered the Absco pool pump shed observatory concept, I've decided I'm going to go down that path too. Today I started by building a mockup frame to check my setup will fit and I've concluded it is a perfect match.

I'm now trying to decide what to do for the floor. I'm looking for a solution that:
1. Can cope with a lot of rain/runoff so it needs to have a bit of ground clearance
2. Keeps ants out
3. Prevent ground moisture creating humidity in the obs
4. Stable so I'm not having to mess with polar alignment all the time
5. Semi permanent so I can remove/move it if necessary

I had a look around Bunnings today to checkout what was available and noticed Absco also make a produce called smart slab. It is a lightweight precast concrete slab that comes in 1.5x0.78 m sections. I'm considering using two of these and building a treated hardwood sleeper base to sit underneath to create some additional ground clearance. I'd lay some plastic sheeting down first then sleepers than the smart slab system. This would require 2 smart slab pieces with a join down the middle - I'm thinking some flexible exterior silicone to seal the gap between the slabs.

Interested in your views on this solution.

Peter

[h0ughy]

1. Can cope with a lot of rain/runoff so it needs to have a bit of ground clearanceyou would need some height from natural surface for this, maybe even channelled to allow the water to pass around it
2. Keeps ants outyou would have to chemical treat the ground maybe Diatomaceous Earth
3. Prevent ground moisture creating humidity in the obsdouble layered 200um black plastic
4. Stable so I'm not having to mess with polar alignment all the timethick concrete slab
5. Semi permanent so I can remove/move it if necessarywell if you want 4 then you will loose the slab and unbolt the top


the pre made slab will break up, they are not very thick:shrug

[peter_4059]

Thanks Dave,

I'm trying to avoid a full on slab for a few reasons:
Access is tight so pouring concrete is going to involve a lot of wheel barrow trips up a hill. I'm also not planning this to be a long term option and want to be able to remove it and re-instate the lawn down the track.

I've been using the bricks embedded in the lawn with a hole drilled for the tripod tips to achieve fast polar alignment for many years and I've found this to be quite stable. I'm really looking to replicate this concept with a bit of additional ground clearance and make it ant resistant.

I hadn't heard of diatomaceous earth being used for ant proofing but it seems it only works while it is dry and able to form a dust so I don't think it would work for long in our climate.

[peter_4059]

Big day today - ordered all the bits. Hoping it will all arrive before Christmas.

I've settled on a different location to my original spot which offers better views to the East and North. I've come up with a floor solution that is a little less permanent than a slab as I expect I'll want to move this some time in the future.

Can't wait to get started now.

[ZeroID]

We need pictures of course ...don't forget. :D

[h0ughy]

is that location clear of your neighbor's light?:sadeyes:

[peter_4059]

Will do



Not completely but less affected than where I've traditionally set up.

[Nortilus]

I'm going down this path very soon myself with the Absco Pool pump shed...however Im doing a poured slab as it will be there for ahwile.

[peter_4059]

Quick update - shed still hasn't arrived and I'm going to hold off constructing the floor until I get a look at the shed. But to keep things moving I've been pruning trees from the fence line and after two trips to the transfer station, that job is done. I've also been digging the trench for the electrical and data cables. Big job digging through clay and shale by hand on a steamy Brisbane day but I'm almost done with that also. I think I discovered a hidden garden in the process - who buries plastic plant pots? Tomorrow I'll get the conduit in and back fill the trench.

I'm hoping the shed will arrive on Tuesday so I can make some progress.

I've knocked off early. Time for a beer!

[astronobob]

Just reading through your project Peter, and I kinda agree David (Hough) as in stability in a base, ? securing sections will have lots of potential to move/tilt about. ?

[astronobob]

Just a suggestion,, maybe three solid 3/4 size bessa-blocks on their ends, approx 300mm high for you tripod legs, use 3 premix bags a concrete from bunnings, one for each block, to form a pyramid around each block, then build up the ground around them say 200mm and then form/build your deck on top ? Maybe a coal chisel and lump hammer to punch/brake some holes through the 'smart slabs to accommodate the blocks ? ?

[peter_4059]

Thanks for the feedback Bob. I've decided against the smart slab and I've gone for a heavier pre-cast option. This one is 60mm thick. It will be resting on a 80mm base of cement stabilised sand with a treated pine box all around to keep everything in place. I'm going to grout the joins to seal from ants.

[peter_4059]

Made a bit more progress today. Got the cat6 and power cables pulled through the conduits and the last bit of concreting around the conduits complete.

Unfortunately the shed is still sitting at Absco awaiting delivery. I'm pretty disappointed with both Absco and Bunnings as I was told I'd get it by Thursday last week. What makes things worse is neither Absco or Bunnings can provide any certainty around delivery date. Pretty crap given they claim 48 hours delivery on these. Luckily I've had enough other prep work to keep me busy.

[astronobob]

Sounds much betterra, the heavier pre-cast 60mm thick option (y)
Bit of a bugga your shed not turning yet, you cant pick it up can you, it wouldn't be a large pack, have it hanging out the boot long-ways a couple o feet with a red shirt ? Or is it a long drive ?
Good your still able to be productive tho ...

[bugeater]

I've been lucky. I ordered mine from Bunnings on Monday last week (i.e. 11 days ago) and was told to expect it in the second or third week of Jan. Got a call 2 days ago to say it was ready and it was delivered yesterday. They seem a bit variable.

[peter_4059]

My shed also got delivered today. I've got most of it assembled this afternoon thanks to help from Allan Gould. I'm hoping to have the rest including the floor complete tomorrow.

[troypiggo]

Photos or it didn't happen

[astronobob]

Lol Troy ,,,

Good to hear its all happening Peter :thumbsup:

[peter_4059]

OK - finally got around to taking some photos. Finished off some last few fixing jobs today. Left to do:

1. Seal the gaps in the floor
2. Seal around the base
3. Wire up the power and data
4. Install a solar powered ventilation fan

I'll then look at how hot it gets and whether insulation will be required.

The floor is very stable so I'm happy with how that worked out.

[peter_4059]

A bit more progress this weekend. The wiring is all complete and I've sealed the joints in the floor with self-levelling cement. I've also purchased the parts for the solar vent fan and done a quick check to see if it works (and it does!).

Final things to do include sealing the floor-wall joint with expanding foam and installing the vents - hoping to have these complete by next weekend.

[peter_4059]

I haven't posted an update for a while so quite a lot has changed since my last update, in fact I'm pretty much declaring completion.

I've sealed the gaps in the floor, installed the solar ventilation fan and completed the wiring.

[peter_4059]

Here's today's final updates. I've installed a vent at floor level on the south side and an extraction fan at the top corner on the opposite side, powered by a 12V 5W solar panel. The floor is all covered in foam mats which is a lot easier on the knees when crawling around.

[h0ughy]

love what you have done

[peter_4059]

Cheers Dave. I'm pleased with how it has worked out. It was a lot more work than I had anticipated but it is nice to not have to drag the gear in and out of the house

[stanlite]

looks good Peter. I have likewise just received the OK from SHMBO for a similar build for my b'day next week. As always your work looks very well thought out and professional.

[peter_4059]

Thanks Grady. Let me know if you want to compare notes before you get started.

[astronobob]

What a grouse project :cool2:
Looking real cosy for the gear, nice neat work and everything you need :thumbsup:

[peter_4059]

Thanks Bob. Nice to have it done at last.

[alan meehan]

Looks great Peter nice and neat and no more moving your scope in and out when you want to use it,well done
AL

[peter_4059]

Thanks Al.

[bugeater]

Hey Peter, what did you use to seal around the base of the walls?

[peter_4059]

Expanding foam from Bunnings

[peter_4059]

Thought I should post a more up to date image with the EQ8 installed. I'm really loving the quick set up time.

[RickS]

Very jealous! I just can't be bothered to set up most nights now that I have to be at work before 7am weekdays for conference calls :(

[peter_4059]

I know that feeling. Work starts for me at 6:45am each morning.

[muletopia]

Peter,
I may be too late if you have already used expanding foam for the floor/wall join sealant. The stuff is not impervious, I suffered from this. See my thread
"a cautionary tale" in this diy obs forum.
Chris

[peter_4059]

Hi Chris,

I've used the expanding foam on the inside of the bottom gutter of the wall sheets - see this image:

http://www.iceinspace.com.au/forum/attachment_browse.php?a=193555

The inside height of the Colourbond channel is higher than the outside height so in theory the water should drain outside before it overflows inside. The point of the foam was mainly to keep ants at bay.

I've sealed the gap between the bottom channel and the floor with exterior flexible silicone sealant:

http://www.selleys.com.au/sealants/silicone/brick-concrete/

Since completing that the only issue I still have is some moisture tracking up through the slab, despite two layers of impervious plastic underneath. It currently isn't causing grief however I have considered applying some concrete sealant.

[muletopia]

Peter,
I found that my 100mm floor also leaks despite the underlay of plastic. I do find that an overlay of the same underlay plastic keeps the interlocking foam floor tiles dry and the trapped water exits via the cast in floor drains. Like you I will apply sealant, what do you intend to use?
Chris

[peter_4059]

Chris, I haven't looked into sealants for the concrete yet but I suspect there are plenty of suitable options to choose from. Have you found something?

[bugeater]

As it turned out the roof on mine was easy to seal - just a blob of silicon on each screw hole.

Took me a lot more goes to get the walls sealed up. Because I've got a wood base, I wanted to seal the gap between the channel and the wood base, to prevent hidden water and rotting. However, this helped keep the water in.

Then when sealing the outside of the channel, even a small leak inside would just store water up until it leaked everywhere inside. More and more silicon eventually solved the problem, though it seemed to get worse before it got better. The door was a particular problem.

I've tried to keep the inside reasonably silicon free, since it at least lets you see if there is any water ingress, rather than hiding it away where things rust and rot.

[peter_4059]

I decided to seal the floor today before reinstalling the mount after astrofest. I've gone for Gripset Betta Damp Stop. Got the first coat done today and should get a second one done this week. It seems to have bonded well to my floor so hopefully it will be successful.

[peter_4059]

More work on the obs today. Added some insulation to the underside of the roof.