Observatory under construction

[middy]

Hi everyone. I have taken the plunge and bought a pool pump cover to serve as an observatory after some inspiration from Richard the other week. I have managed to assemble it despite some errors in the instructions.

My problem at the moment is how to seal the base to stop rain getting in. The slab was an existing slab when I moved in to the house and, to be honest, whoever laid it did a terrible job. It is uneven resulting in gaps under the shed in several places. The largest gap is about 10 mm.

Does anyone have any suggestions on the best way to seal around the base before I bolt it down? I have attached a pic showing the largest gap.

cheers,
Andrew

[louie_the_fly (Stew)]

What about if you set it up say 25mm (average), secure it down with some brackets and packers, then grout under the bottom edge? I'm sure that'll work.

[glend (Glen)]

Gap sealer foam in a can will work fine.

[rmuhlack (Richard)]

this is what I used to seal the edge of mine: http://www.bunnings.com.au/selleys-4...alant_p1230973

[h0ughy (David)]

just some clear sealant

[middy]

Thanks for the info. So the concensus so far seems to be to use large quantities of silicon sealant. I was a bit worried whether it would work ok on such a large gap.

[MrB (Simon)]

I would run thick adhesive foam tape around the underside of the shed then secure it down.
Something like this: http://embossingtapesupplies.com.au/..._Foam_Tape.jpg

Edit: Bah! I've never been able to embed images at IIS. Ignore the supplier, just using their image as an example.

[ZeroID (Brent)]

As GlenD says, expanding foam filler solved my water problems. Fast curing, gap filling, easy to squirt in ( quite fun too .. .. just don't over do it as it EXPANDS )

[middy]

Hi folks. A quick update. I decided to give the expanding foam a go, so I filled the gaps with it yesterday. I still need to go around with the silicone sealant today.

[Long story alert!!]
Anyway, yesterday I set the mount up in there with the telescope to mark the position where the mount will go. It was forecast to be a clear night so I thought I'll leave the mount setup and have a 'pre' first light. I planned to do some planetary imaging due to the more relaxed polar alignment requirements. I wanted to get a better Neptune image than my first attempt a few years ago.

So I went out after dark and there I am slewing to an alignment star ...... grind, grind, crunch, clickety click, grind, grind. What the?!?!?! Cart everything back inside again. That was the end of my 'pre' first light.

It turned out to be the screws for the worm housing on the declination shaft. They had loosened over time and the worm drive had shifted off the gear and was skipping. I decided to strip the Declination axis down while I had the covers off and give it a re-grease and adjustment to try and get rid of a slight binding it had at one position. Two hours later it was back together with fresh grease. The binding seems to have gone but it is still stiffer to turn than the R.A shaft. I can't get it to turn as freely no matter what adjustments I make.

Tonight is forecast to be clear again for the post-pre-first light. Wish me luck.

Andrew