Astrokev

Yes, the astronomy and nature centre chap. Loved his videos for a good laugh, but I'm sure some may have been taken in and persuaded to part with hard-earned cash for his over-engineered piers.

I like thought experiments, but one could argue it's no easier than imagining fixing the pier, then loosening the alt-az adjusters, which allows you to move the PA wherever you like. I guess it depends on which frame of reference you find easiest to visualise. ?

Yes, his videos were quite entertaining. Most of it was utter nonsense as I recall, with liberal use of terms that were, I'm sure, previously unknown to mechanical engineers. Is he still around, or in hiding somewhere?

Looking excellent Alex. Shelving looks very professional - is this in the warm or scope room? I haven't given too much thought to shelving for equipment, other than recognising that I probably need some. Once I've got the electrics in, I'll see how best to use the space I think.

I am a Type 3

Yep, but I have no idea what belief type that is, maybe 6

Some good progress James. Pier looks great. I assume that’s the lavender cupcake in the warm room? Looks more pink on my phone....Suits you Sir!

Interesting. Why do you say that?

As I mentioned, I made sure the pier was vertical (for aesthetics). The level top is achieved by adjustment of the 4 bolts attaching a top aluminium plate to the pier. I used a spirit level to get this as accurate as this method allows. On a more practical note, having a level mount probably makes polar alignment quicker, since this allows adjustment of the position of Polaris, through the polar scope, in azimuth and altitude to be done completely independently. If the mount is not level, an adjustment of azimuth will also give a small shift in altitude, and vice versa, requiring continuous adjustment in both axes to complete PA.

...and you then go on to list 4 points ?. “What did the Romans’ do for us” ! I too found it difficult to visualise at first that a non-level pier would not affect PA. The scientist in me was bothered by this, so in Heath-Robinson tradition I constructed a quick and dirty “model” out of scraps of card/paper and pencils to help get my head around it. After playing with this for a short while it became very clear to me that PA was unaffected by a non-level pier. That said, when I built my pier I tried to get it as level as I could because I’m a bit OCD and it would have niggled me if I didn’t! ?.

I have no intention of removing my pier if I ever move, or the observatory for that matter. In my view, regarding any future sale, it’s a case of “buy as seen”, as was the case when I bought my property. I’ve never heard of any situation where a seller has ever been liable for any injury to a buyer, and can’t believe this is a risk. Regarding mount levelling, which you seem unsure about, it is 100% correct that the pier does not need to be level. Providing you can adjust the mount / polar axis in both altitude and azimuth then you can point the PA to any point on the sky (obviously constrained by the limits of the adjustment!) and can achieve polar alignment. A non-level pier top makes absolutely no difference and is unimportant.

I think I'll have to get myself a couple of the temp/RH displays. My experience of humidity sensors at work was that they require periodic calibration, but I suppose for the accuracy we need for observatory use, they should be fine.

Good idea, but I'd need to plant some grass seed first! ?

I can understand that. Lavender Cupcake has a certain appeal!

Been suffering blocked sinuses over the last several days so haven’t felt like doing much at all. Bit of a waste of the fantastic weather over Easter, but when you feel like your head’s about to explode, all you really want to do is curl up in a ball. Starting to feel more human again now so hopefully will be able to at least start the path etc!

Sounds like a plan James, but wouldn’t it have been easier to paint the ceiling first? You’ll now have to be careful you don’t drip or splash ceiling paint down the walls!

I guess that makes sense ??

Here are a few pics from my build thread which show more clearly what I was trying to describe above. All joists around the edges rest on EPDM acting as a DPC.

I am tending to agree. With time I think water will soak into the weatherboard, or seep underneath it by capillary action, and have an unimpeded route to both the wall linings and the floor. In my build, I essentially positioned the wall to lie above the edge of the foundation concrete (resting on joists running around the edge of the structure. I used EPDM rubber as a barrier between joists and foundations). The wall membrane covering wall and joists then terminates below the top of the foundation concrete. Water running down the cladding simply drips off onto the floor. Your final design with the DPC looks more water tight, but the sleeper will still be sitting in a pool of water.

Yep, same with mine.

Agree with James’ comments. I too went for V profile track and wheels and have no complaints. I’m not sure what the functional difference is between V and round section, but I agree that round may suffer a little more friction due to extra area of contact. Is there a reason you’ve gone for round?

With the vagaries of uk forecasting, I’d be prepared for anything!

Continues to look great James. I guess it’s a good feeling to get that messy job ticked off.

I guess the difference is, I don't live in the middle of Devon! My neighbour has a similar security light, that I'm sure could be seen from low earth orbit. He has it angled such that it fully illuminates a pine tree to the south-west that's taller than my house, and the tops of my house's gable ends. The problem is, whilst being a nice chap, he's outside in his drive until midnight every night, working on his endless outdoor projects, which sets off the light. I think he's allergic to being indoors. Ridiculous I politely spoke to him about it a few days ago and he said he would look at lowering the angle, but hasn't done so yet. ?

How d'you plan to attach the steel tube to the plate?