Lockleys Observatory

[TheDecepticon]

Just a brief note to say that I finally built my own observatory that I got second hand from a society member who was shifting interstate. Just waiting for the electrician and some carpet.

Piccies can be found

http://www.pbase.com/grahammeyer/lockleys_observatory

Enjoy. :)

[rogerg]

Nice! congrats :)

[Rigel003]

Looks terrific. I'm envious. That will mean an extra hour or so each session that can go towards gathering data.

[h0ughy]

well done - what a brilliant christmas gift

[Larryp]

Looks great!

[TheDecepticon]

Thanks guys! :)

It certainly is an awesome Xmas gift, Houghy, am looking forward to the official opening and first proper image. :thumbsup:

An extra hour of image will certainly be welcome, Rigel, that is for sure. :D

[byronpaul]

Great home for the scope!!!!

Any chance of some close-up shots on the roof roller system?

Paul

[TheDecepticon]

Yeah, no worries, Paul! I am heading home today from holidays and have some more shots to upload any way, so I will include a few of the rollers and rails. It is very simple and effective. :)

[brian nordstrom]

:D Well done ! thats awsome for 4 days work , good luck with the finishing touches , and please dont forget more photos .
Thank you .
Brian.

[allan gould]

Excellent, hope you enjoy it.

[ChrisM]

An excellent home for your gear. I hope that it gets a lot of use!

Chris

[TechnoViking]

Very nice observatory!:thumbsup::thumbsup: hopefully the weather treats you well, so you can enjoy observing in comfort!

The best carpet to get in my opinion is the carpet tiles (Synthetic type) I got mine 2nd hand for a $1.50 each from an ex-government shop. They are water proof, rubber backed and very tough wearing.

I installed mine without glueing it down, so i can lift a tile out if it gets dirty and jetwash it clean, takes a day to dry, then you can reinstall it again :)

[TheDecepticon]

Thanks for your comments guys, was a solid four days of work for sure! It certainly is a great place to store the gear and it is wicked to just roll the roof off and on and not have to pack up all the cables and stuff. :thumbsup:

We did find some carpet, but it was too pink for the obs, so we will put it in the daughter's room and I will have the tile squares that come out of there. Done deal with SWMBO. :D

I have uploaded some pictures of the roll off roof that I hope explains it a bit for those that are interested.

http://www.pbase.com/grahammeyer/roll_off_roof

The rollers used are very similar to the ones pictured, however; only use a two wheel set up not four. Basically, the top rails on each roof supporting side are 6m long and do the job of roller rails and joiners to the two upright poles. The rollers slip inside of them and the roof movement is limited by two stoppers on one end of the roof. A very eloquent and simple approach. :)

[moonunit]

Really like this, what are the dimensions, also what are these roll on roll off roofs like in windy conditions?

[Peter Ward]

I see the EQ head seems to be sitting on a plate supported by 3 leveling bolts.

Can I suggest you loose the bolts and discover a significant improvement in stiffness of the mounting and increase in the natural frequency of vibration of the pier + EQ head ?

EQ heads need polar aligning, but they simply do not need leveling.

The EQ head/pier combination however works much better when it is rigid, rather than acting like a spring ;)

[troypiggo]

I've often wondered why people do this too. All that money on expensive mounts etc, then sit it all on 3 extended bolts (usually around M10-M12 diameter). In structural engineering design of buildings we'd call that a "soft storey."

[Bart]

Can you explain why it does not need levelling? I am thinking of setting one up so it would be good to know. Thanks. :D

[troypiggo]

Your polar alignment takes care of any slight out of level from the tripod or pier plate.

[ChrisM]

My understanding is that for an equatorial mount, the polar alignment process will be less iterative (between Alt & Az adjustments) if the base is level.

In my case, I needed to gain some more pier height, so rather than make a new one, I used 4 x 19 mm threaded studs at ~250 mm centres. This arrangement is quite stiff and does not lower the natural frequency much.

Chris

[bojan]

It he pier is reasonably in level (within degree or so, this is easy to achieve during the construction), the benefit of this mechanism is negligible.. not worth the cost.
Even if you need another iteration , so what.. it is done only once anyway... maybe you need to check in couple of months (concrete slab will settle by then)

[Bart]

None of this explains why it doesn't need levelling or what is meant by frequencies of the pier and mount head. :shrug:

[bojan]

Levelling of the pier is not so important because the mount itself has all provisions for alignment (N-S. Up-Down screws).
The frequencies are different matter altogether.. but also not very important - the important bit is damping of oscillations of any frequency at which the whole setup may oscillate, when bumped (accidentally or intentionally), and their amplitude.
Usually, the more massive and sturdier the pier, the smaller the amplitude and the higher that frequency is (because then only mount itself and the load (telescope + accessories) are the factors), and the duration of oscillation is shorter - a very desirable situation.

[Bart]

So in other words, it is all bollocks. :question:

As long as the pier is sturdy and is not an obviously flimsy setup which is susceptible to wobble and vibration, then there is no reason not to use a levelling setup.

Also, if levelling helps reduce the number of polar alignment iterations, then that has to be a good thing as well.
:)

[bojan]

Exactly right.

However, if you crunch some numbers, you will see that if you are levelled your pier within 2-3° (very easily achieved during pier construction phase), the number of required iterations does not really increase (it can be said that the alignment error of each iteration will be proportional to sin(x) where x is the departure from ideal horizontality of the pier base.. so sin(2°)=0.035.. 3.5%.. not really significant.
After all, who guaranties that the base of the mount itself is really aligned with the horizontal axis of the polar axis?
EQ6 base is just aluminium cast, no machining.. so go figure ;)

[cfranks]

I read Peter's comment as being more concerned with the 3 long leveling screws. Compared to the pier, they would act like a wobbly spring.

[troypiggo]

It's as simple as this. You have a 3 tripod legs connected to a plate that holds them together. Rock solid. Alternatively you have a column type pier that is suitably sized to be rock solid. The plates on top of these can be levelled to pretty close to horizontal. Any other accurate levelling is taken care of when you polar align your mount.

You have a mount and telescope sitting on top of that. Rock solid.

If you then put 3 slender bolts with inadequate stiffness between the 2 rock solid parts, you've created a potential zone of weakness. Critical in that statement are the words "slender", "stiffness" and "potential." So it's not to say that you can't do it, as there are obviously people who have done this and used with success.

Slenderness is a function of the bolt diameter and length. Stiffness is a function of bolt diameter, length, and material properties. So there's going to be some point where you've got a short enough and/or large enough diameter bolt where the effect of using them is negligible. The fact that they're there means they will always be a little more potential for weakness, just a matter of how much.

But at some point you will be either too long or too small a diameter bolt for that length, and it will noticeably be a weak point in your train.

So all I'm wondering is, as long as your pier/tripod is close to level, and your mount can be polar aligned on top of that, what's the point of introducing a potential zone of weakness. When I'm using the term "weakness", I'm not saying the whole thing will collapse (although if you had some huge/heavy PME and massive RCOS on top etc, I would certainly be checking the bolt length), but I mean movement, vibration etc that are critical for astroimaging etc.