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Concrete pier, all done.

ollypenrice

By ollypenrice
in DIY Observatories

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ollypenrice

ollypenrice

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So to recap, this is a concrete pier made by epoxy-bonding four pre-formed concrete cylinders together and to the ground, bonding in some rebar, filling with concrete and giving it a few days to harden.  All very easy.

The adapter plate, which has to be fairly level because the scope will be in Alt Az mode, had recessed holes on the upper side so I bolted five lengths of 10mm threaded bar through it, allowing for a 6cm gap for getting to the central scope bolt and 14 cm penetration into the concrete. I put epoxy into the holes and then pushed and tapped the plate and threaded bar down, using a spirit level at the end and a bit of one sided tapping to get the plate pretty level. It was then easy to fine tune the levelling once the epoxy was hard. I'd probably have gone for bar rather thicker than 10mm but that was what the adapter plate could take and I hoped it would be adequate. It certainly is. The plate feels very solid and tapping it with the scope on hardly affects the view at all.

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Next came the alarming 'two-person plus one scout' lifting of scope onto plate. I'd put the centre bolt in already and put a piece of foam under it to to spring load it upwards. This worked well and made life easier. No disasters so far...

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Next up was to read the manual (OK, some of it...:evil4:) to find out how the GPS system works. I'm always very pessimistic about electronics but, to my delight, the scope ran through its little orientation dance and seems to do just what it should. Tonight will tell!

I've never used one of these microfocusers before but it looks good and works on terrestrial targets nicely. You can set the focus quickly with the mirror mover, lock it and fine focus from the handset. Cute.

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This morning I ordered Telrad, not only for finding alignment stars but for showing where the scope is pointing. I think this is important with GoTo scopes and we can also use it as a cheat: if someone is struggling to find a target in the Dob they can use this scope to put the Telread in the right place and copy its position in the Dob.

And this afternoon I'll get down to the woodyard and re-clad that scruffy roll off shed before I get told off on here.

:icon_biggrin:lly

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AKB

AKB

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1 hour ago, ollypenrice said:

This morning I ordered Telrad

...very nice.  Like a Telrad.

Of course, on my scope it looks huge, on yours, you will struggle to find it.

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ollypenrice

ollypenrice

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16 minutes ago, Craney said:

That looks a nice neat pier.  Can you adjust the height by taking out or adding the pre-formed blocks at a later date, or is it that height for the foreseeable future ??

Sean.

I guess I could add to it easily enough. Just buy another concrete cylinder or wrap somethng semi-flexible around the pier and a bit higher, then pour concrete into it. The present pier is the highest possible with the scope pointing at the zenith, so it can't get bashed by the rolling back of the 'sentry box.' As it's concrete filled I can't shorten it.

Olly

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ollypenrice

ollypenrice

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38 minutes ago, Alan White said:

Very nice Olly, looks good.

As to recladding before anyone tells you off:
why not rub it down and revarnish it, far less wasteful, unless of course the woods gone, the clad away dear sir.

The wood's corpsed! I used 'bardage' which is a kind of outdoor wide tongue and grove but the intense sunlight has warped and shrunk it so there are now gaps between the panels and they are very twisted.

For my later sheds I just used marine ply. This isn't as attractive but it lasts longer and doesn't warp. It's easier to sand and re-varnish, too.

My standard construction, based on fifteen years here, is ply for the sides and corrugated galvanized steel for the roof. Cheap and bomb proof.

Olly

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ollypenrice

ollypenrice

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1 hour ago, michael.h.f.wilkinson said:

Looks very sturdy. Is that the Nagler 26T5 in the diagonal? 

It is. It will be interesting to compare the scopes. The big advantage of the 14 will be the GoTo because, when we have mixed imaging and visual guests, it's very hard for me to help at the Dob and visit blazing computer screens on and off.  Even beginners can be independent with the GoTo.

Olly

Edit, I hope the 14 will be tasty on the planets, too.

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ollypenrice

ollypenrice

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1 minute ago, darknight said:

olly, can I ask why separate bits bonded together, rather than a straight pour?

but yea a Holiday there is on the books I think, also not needing to bring gear on hols will be a space and nerves saver :)

It's really a mixture of both separate bits and straight pour. I could have used cardboard or PVC tube as shuttering and poured into that. However, this would have meant contriving some support for the shuttering to keep it upright. Not difficult but more time needed. By using the pre-formed cylinders I could just bond the first one to the floor then put on the other other three, bondng each to the next. This was so dead easy because they naturally fit together and stay put. Once the cylinders were in place I poured concrete into them as I would have done into a tube. So in a nutshell it was easier and quicker to do it this way and I'm pushed for time since we're up on all clear nights for the next fortnight and I wanted present guests to have a chance to try the scope.

Olly

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michael.h.f.wilkinson

michael.h.f.wilkinson

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1 hour ago, ollypenrice said:

It is. It will be interesting to compare the scopes. The big advantage of the 14 will be the GoTo because, when we have mixed imaging and visual guests, it's very hard for me to help at the Dob and visit blazing computer screens on and off.  Even beginners can be independent with the GoTo.

Olly

Edit, I hope the 14 will be tasty on the planets, too.

I hope I can be Dob pilot so you can focus on the imaging kit at some point once more. I have very fond memories of Sir Isaac under the gorgeous, dark, warm Provençal skies.

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ollypenrice

ollypenrice

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1 minute ago, michael.h.f.wilkinson said:

I hope I can be Dob pilot so you can focus on the imaging kit at some point once more. I have very fond memories of Sir Isaac under the gorgeous, dark, warm Provençal skies.

I'm sure that could be arranged!

Olly

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ollypenrice

ollypenrice

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21 minutes ago, michael.h.f.wilkinson said:

Not this year, we are going eclipse hunting in the US

Of course! We are having a pretty quiet August this year with so many heading over the Atlantic. Have a good one! 

Olly

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ollypenrice

ollypenrice

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I'm now rather less impresssed by the electronic focus because when you plug it in to the control panel the slewing fork collides with the plug. It is clearly the original plug and is a right angle model but still too high to clear the fork.  If I'm missing something I don't know what it is!

Collimation wasn't far out despite two miles down Alan's rutted Shropshire track in our rustic 4x4 and then the drive down to SE France. We ended up with very pleasing views of Saturn, excellent when seeing allowed (270x and 218 x).

We were too busy imaging on two other rigs to spend long on the GoTo but it was miles out on the first alignment star after its GPS routine. The second star wasn't too far out, but then it told us that Saturn was below the horizon, contrary to the sensible and true avouch of our own eyes.

I can feel a bit of manual perusal coming on...

But a pretty good start.

Olly

 

 

 

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