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upahill

Semi DIY Temporary Obsy & Motorising Project

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So its a pre-fab dome but im planning some pretty hefty mods so this may well fit here. Just wanted to document it as I go but it will be a long project so no daily updates!

After a horrendous drive we arrived to pick up the dome, and started dismantling. The dome would just fit in the luton van on its back if it went in at angle. But the base was too wide for the doors and too tall to go in at angle. Originally the base ring was manufactured in 3 parts and joined so with an angle grinder in the pouring rain I put some quick cuts in and got loaded.

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Im going to create 3 panels with a rubber seal to allow these three cuts to be rejoined and bolted - but wont repair the fibreglass. As I will likely need to move the dome at some point in the next few years it makes no sense to repair fully and the parts are a lot more manageable as 3.

In the back of the van:

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At the moment we are in rented accomodation so I have a couple of considerations to make.

  • Maintain ability to transport the dome easily in the future (keep seperate)
  • No large concrete slabs in the garden
  • Removeable base with nothing left behind
  • Shielded somewhat from view of neighbours without obstructing my views.

We have a great view to the south which I dont want to obstruct by placing the obsy at the bottom of the garden, which would be its best location for sky access, so instead it will be at the north end of the garden. This presents some terain challenges as the ground is dipped and a few inches down are large rocks (several tonnes).

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This restricts my view to the east/south east but gives me pretty good south, west and semi-good northern views (once the hedge on the north edge has been cut down slightly. Large ferns to the immediate east of the dome will need to be trimmed significantly.

My plan for the base is to dig 5 holes, since at best ill get a foot down before hitting rock and the levels are so different ill use a hardcore sub-base, followed by a breeze block pillar in each corner. The pier will be breeze blocks with threaded bar, then the blocks will be back filled with concrete. It's not going to be super sturdy but better than what I have and can be easily pulled out and put in a skip whilst hopefully maintaining the wooden frame that will sit on top.

The sleepers will create a square frame that can be decked - isolated from the pier

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Motorising the dome may proove a bit trickier. An upper and lower set of rollers run along the rim, but I would like to come up with a solution for motorising it without putting the motor in the roof so thats my next design hurdle. The shutter isn't overly smooth on its current rails but could probably be opened and closed using a simple pulley/motor system, that will have to wait until assembly to design.

 

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Didn't think it would ever stop raining and then the hottest weekend in ages happens. Managed to put aside the myriad of other projects for the two days and get started on the deck.

The gradient was a little worst than I had imagined in my head. Almost 20" on one corner to level up the rear. Since its higher than I planned I splurged on some larger wood so I wouldn't need to prop up underneath as much. This is all temporary and as such there is no major construction going on - just whatever works and is cheap. In this case, 4 bags of postcrete ;)

Somewhat askew...

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That's better...

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Everyone else was at work this weekend so was left to levelling on myself with what were suprisingly heavy lengths of timber. If anyone asks the slight slant is for rain to run off ;)

So you might be thinking it would have made sense to put the pier in first whilst there wasn't a honking deck in the way..... you would be right.

I have a plan though. There is only about 2-5" of soil above giant boulders anyway to I can actually dig out via the hatch, shutter up and bury some bolts into the boulder before concreting.

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All done and tidied up, we spent ages arguing about colour and ended up with a colour called "£10 a tub" - I think it looks pretty good though.

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Got a couple of braces to add, some weed mat to feed through (i know), and some cladding to tidy up the exposed edges but its basically ready for the dome to be bolted too. Then onto pier base construction, I have a nice metal pier to go in now but may keep the todmorden up as visual scope pier for when im imaging and either put the 10" newt on it, or the LX10.

Once the pier is in and mounted the central square will have a filler piece dropped in to seal off the outside and prevent the trip hazard.

Stability is a 8/10 - and it can be removed in minutes which meets my main criteria.

I have however given myself 3rd degree sun tan burns though, so typing in agony. :(

 

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Well it fits, and have bought some hardware to bolt the sections back together. Going to need one heck of a good scrubbing.

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You're going to get some terrible diffraction effects off that washing line, you know :D

Nice to see it starting to come together though.  I understand your problems with the slope.  Mine's just as bad.  One the positive side, it does make for easy access to get wiring in from underneath :)

James

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2 minutes ago, JamesF said:

You're going to get some terrible diffraction effects off that washing line, you know :D

Going to add another washing line at 90 degrees to get even diffraction spikes :D

 

Haven't given much thought to the wiring, those 6 black splodges of silicone are bolts that hold a board with a consumer unit and sockets, very tempted to just put a caravan power socket on the outside and run an extension when in use. I use similar leads as can be seen for the current mount as I cant really tunnel out with proper wiring underground. The big connectors mean I can unplug for mowing etc too.

I wanted to run cat5 buts its messy so just going to improve the wireless in the garden I think.

 

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The dome is on!

Four of us just about managed to carry the dome through the barn, across the field and over the fence to get it into place. Im already not looking forward to getting this out of here in the future.

My rejoining method has a slight bit of unevenness in each of the three panels which was painfully obvious once the dome was on, but I have since managed to compensate for that. With the weight of the dome on the deck structure is clearly starting to strain a little, im not too bothered as it wont be for visual use, but more as a remote obsy and the vibration in the deck will be isolated from the pier anyway. Providing you dont bounce up and down on the deck when you are visually observing its not too bad and some concrete pavers and bottle jacks underneath may mitigate this if it becomes more of an issue.

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Got the meade in there for a bit of fun (and to appease the wife who has been tripping over it in the hallway, had some cracking views of the lunar eclipse, saturn and jupiter that night. The LX10 is fast becoming my favourite scope ¬_¬

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There are 8 rollers which site on the fibreglass ring, at any one time about 6 actually touch it. It may be worth me considering building adjustable brackets - but generally it was quite smooth if a little noisy.

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The 3 sections are bolted together along that fibreglass ring, and agin about 2/3rds of the way down the ring with fixing plates. This is hopefully going to be enough and whilst the joints are taped over at the moment I will likely come back with either a plastic plate to cover them entirely or just re-fibreglass the joins.

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Underneath the dome are the remaining rollers, these help to centre the dome on the lower ring and have smoothed out the operation of the dome significantly.

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The biggest bug-bear I have right now is the aperture opening, it is far from smooth, or elegant. I would love to automate this eventually but right now the mechanics of it are appauling and it just doesnt like to open/close.

There are two thin rods, attached the base of the dome, and then to the aperture, with just some electrical glands as runners - there must be a better solution but cant think of one.... :(

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It's quite roomy inside really for the small dome.

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The electrical centre will become a table for the tablet that runs the scope to sit, with some shelves adjacent to it. Im hoping to go from this tablet to a hub on the scope with a single USB-C lead, and 12v power.

Fairly happy with how its going, no idea how to motorise the shutter or dome yet but hopefully someone has some good ideas for me :)

Going to have to scrub it clean soon....

 

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I have the same Pulsar Dome, which I collected, on a flat back lorry, from a fellow astronomer in Wales and can appreciate the physical effort moving & installing it. 

I have automated my dome and hopefully will attempt to automate the shutter this summer.

Pulsar Dome Automation

Steve

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22 minutes ago, sloz1664 said:

I have the same Pulsar Dome, which I collected, on a flat back lorry, from a fellow astronomer in Wales and can appreciate the physical effort moving & installing it. 

I have automated my dome and hopefully will attempt to automate the shutter this summer.

Pulsar Dome Automation

Steve

Just read the thread, thanks, that video is amazing and shows such a smooth rotation.

You have gone for a solution similar to what I was thinking, a shelf attached to the inside of the dome above the base ring, I was looking at epoxying bike chain around the outside and using a sprocket to drive but your belt system has irradicated the fears I had of that having a poor mesh. So I may just have to shamelessly copy it :D

What's the saying ... imitation is the sincerest form of flattery 😆

Trimming it with the router is genius, im not sure how much horizontal movement I have in the dome itself but as someone said on your thread i suppose an idler on the other side of the dome would reduce that issue if it came up.

The other idea I had was a friction roller wheel on the shelf itself, with tension wheels underneath it, but never really liked that idea as it would be tricky to guarantee constant contact.

 

Is your shutter as much of a PITA to open? Maybe I just don't have the knack of it yet....

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Glad you liked it. I must admit it went together better than I'd hoped and the Dome has run flawlessly ever since.  If you spring load the motor onto the drive belt/chain you do not need the idler wheel, just make sure you have ample adjustment to take out any movement. Once adjusted it runs without any further adjustment.

The shutter is certainly a PITA. I have purchased four roller blade wheels which I am going to affix on the shutter. These will run over the dome to make the action nice and smooth, I will also mount two 20mm square upvc rails at the rear of the dome to keep the shutter aligned and securing brackets to stop the shutter from lifting. The thin aluminium rods will be discarded. The drive train will be bicycle chain driven by a 12v Dewalt drill motor, the slack chain taken up by derailleur sprung loaded arm. Travel both ways dictated by lever switches and all driven by the Levesdome hard & software.

Steve

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Nice purchase,
I watched that dome on eBay out of interest, glad it's found a good home and will be used.

When I first read about cutting it up I was horrified, now you have it assembled it looks good.
Were these made as one piece in the past then?

Clear skies and good luck with the remainder of the project.
I have restarted an observing area project with dreams of an observatory one day.

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24 minutes ago, Alan White said:

Nice purchase,
I watched that dome on eBay out of interest, glad it's found a good home and will be used.

When I first read about cutting it up I was horrified, now you have it assembled it looks good.
Were these made as one piece in the past then?

Clear skies and good luck with the remainder of the project.
I have restarted an observing area project with dreams of an observatory one day.

I was horified to do it to be honest, but the largest van I could get was a luton, and it was pouring down so couldnt even set up for nice straight cuts. Next time its dismantled it will get fibreglass lips installed for bolting.

If it had been 20cm smaller in diameter we could have got it in, but there was no way (I even made a cardboard model of the van, dome and rear door to try!

Originally these were supplied in one peice from what I gather, and later editions were as seperate panels. The cuts I made were along what looked like factory joined seams.

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I have been reluctant to dig the hole out for the pier in this weather for obvious reasons but might make a trip to T.P tomorrow to pick up some blocks and pavers.

Since im re-using the metal pier my current plan is to dig a 450x450 hole as deep as it will let me until I hit rock (probably 8-12 inches) then build my height back up to the level of the deck using two side by side hollow blocks in alternating directions per level.

Will either glue or mortar each level - I drew out the existing hole pattern from the base and pending any major mis-measuring I should be able to fill the cavities with wet concrete before lowering a 450mm paving slab onto the top with the 4 studs sticking out the bottom with bends in.

When that sets im hoping for a level slab with 4 embedded bolts at roughly the height of the deck + a few mm for a floor.

Is it best to backfill with soil around the blocks once buried, or use something else to fill the gap and add a little extra vibration damping?

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Im going to end up with horse stall mats in the obsy I think, cut to semi circles and just a few mm off the pier itself, there will be an extension of the deck to fill the rest of the gap first whilst not touching the pier.

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Spent a couple of hours digging out in this mad heat - only about 12" down so far, having to break away at stones to clear them out with a shovel. I wont be going much deeper.

I picked up 12 breeze blocks today, im just reluctant to hand mix 20 bags of concrete - these are a little easier to handle :(

My pier base method seems to change every time I go in there.

This has less mechanical connection to the mass, but I think it will be ok for my needs.

 

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I should be able to get 12" below ground, the other layers will take it up to the deck, so in theory the slab will be the only thing protruding into the obsy itself. Ill M10 bolt the pier to the slab and chemically fix it to the slab, then set the whole slab and pier into a mortar bed for final levelling.

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I don't envy you, digging today.  I was doing some woodwork outside this morning and at lunchtime I had to change my shirt because it was sopping wet.  The humidity was desperately unpleasant.  Actually, when I say "change", I meant I had to peel it off.

James

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Its been horrific today, I was dripping wet in B&Q lugging the blocks around the store, almost got to the car and realised they had charged me for 12 rolls of turf at 4x the price, so lugged them all back again.

They are staying in the car until later tonight I think :D

 

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We'll just about be acclimatised to the heat when the weather will change back to normal and we'll all be freezing!!!  Haven't done much today myself.  My usual walk up the hill before it got too hot this morning and a rest on the bed this afternoon.

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21 minutes ago, Gina said:

We'll just about be acclimatised to the heat when the weather will change back to normal and we'll all be freezing!!!  Haven't done much today myself.  My usual walk up the hill before it got too hot this morning and a rest on the bed this afternoon.

Yep, its usually at that point that I realise I havent got heating oil 😆

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That took too long but almost at the finish line (pier wise)

Dug the hole as deep as I could before hitting stone and ended up shovelling out with a cup. First row of blocks held in with concrete and today have added two more courses of blocks + a slab.

Hopefully the mortar is going to set properly and not turn to dust like the last time I tried laying bricks :D

Current plan is to drill the four holes for the pier and drop in some anchor bolts. Need to figure out how they work but should be straightforward. Bolts should go through the slab and grip into the block. The slab is levelish <2-3 degrees either way.

Ill tidy around the edge with some foam and fill the gap with deck boards - then centralise the dome around the pier before bolting that down.

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Excuse the mess.

It's not the largest pier but its ~300kg all in on stone boulders so should be fairly stable.

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Posted (edited)

Swept up and got the pier in place to get a feel for it. Its probably a little high but only having a tiny frac on it for now so im actually pretty happy as it means I should be able to see over the base ring easily and capture the low southern sky if needed.

Next job, drilling holes :D

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My love for alexa has returned so will be installing a wireless repeater, echo dot and RGB bulb in that light fitting, so "Alexa, observatory lights to 10%" should give me a nice dim red glow when needed. I can also switch them off from indoors if I forget. Ill tie this into the rest of the automation when its ready and maybe even write some custom skills for opening dome roof and positioning.

I am also toying with the idea of painting the inside of the dome a darker colour - is this a good or bad idea? I feel like it might make sense.

The peg in the pier adapter is going to need a new hole drilled and tapped too Its about 45 degrees out as it is

Edited by upahill

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Picked up a bit of a bargain at the carboot today (if it works).

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As it stands the unit will change four outputs based on windspeed and/or rain. Not sure if I will use the interface box on the left or just just the sensors on the right and try to interface with them in some otherway (maybe even get some data logging going on)

I need to do a bit more reading up on how I can use it but thought it was a pretty cool addition to the project.

Also managed to score some foam tiles for the obsy so thats the next project in there I think.

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On 01/09/2019 at 14:59, upahill said:

Picked up a bit of a bargain at the carboot today (if it works).

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As it stands the unit will change four outputs based on windspeed and/or rain. Not sure if I will use the interface box on the left or just just the sensors on the right and try to interface with them in some otherway (maybe even get some data logging going on)

I need to do a bit more reading up on how I can use it but thought it was a pretty cool addition to the project.

Also managed to score some foam tiles for the obsy so thats the next project in there I think.

So the more I look into this, it seems it would be great for controlling mains voltage actuators - but lacks the fidelity I want, since the output from the sensors is nothing more than terminals I feel a arduino nano tucked in the box on the right and a relay control board would give me more control and better integration with software so might not even use the main controller.

The expanding bolts in the concrete blocks was a fail, they wont expand fully and grip the block as they just spin (despite using the correct size drill etc.) I now have the PITA job of trying to get them out of the holes. I have a set of Resin anchor bolts arriving in the post tomorrow which I am hoping will do better, they are the type with the hex head on the top to stop them spinning when I tighten down the pier so fingers crossed by tomorrow night the pier will be mounted and some pipe for a cable run will be underneath the deck.

 

 

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So the pier bolts were an epic fail, just tight enough to never come out, loose enough to not be able to bolt down the pier. Because I couldnt get them out I was forced to either a) replace the top slap and potentially top course of blocks or b) swizel the pier 45 degrees.

Its not glamourous, but option b saved a lot of time! I ordered a resin anchor kit from Amazon and when it eventually arrived set about making a wooden holder to position the bolts, the resin was VERY hard to squeeze into the holes, but I think there is enough in there to do the job.

Hopefully the next time I do this it will be a poured pier. So will never have to deal with this stuff again.

A side effect of rotating the pier is that the peg is closer to north and may actually be useable.

It doesn't look that bad does it? It's pretty solid.

 

This is my pier - there are many like it but this one is mine...

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Ill fill the holes in the slab.

Next step is centring the base ring around the pier and fixing it down to the deck, filling the gap in the floor then laying a floor of rubber tiles.

 

Edited by upahill
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Looks fine to me.  And no-one will ever see those holes in the dark.

James

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4 minutes ago, JamesF said:

Looks fine to me.  And no-one will ever see those holes in the dark.

James

A fellow pragmatist! Im still unsure if the inside of the obsy should get a lick of paint. White seems counter intuitive to me, but haven't seen anyone really painting the inside of their domes.

The only time I should be in there is to set something up or fix something, so things like the bolt holes, the slight wobble of the deck etc are not going to be a major issue for me - whereas budget was :)

I may yet fix the deck movement with some additional bracing and posts, but no hurry on that - the next big part of the plan is to copy steal replicate lovingly recreate the dome rotation method which Steve used in his. About to order the 16mm AT10 belt from Germany and a Velleman board for the Levesdome project.

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Not sure I can see much reason to paint the inside of a fibreglass dome, I have to admit.  Perhaps a darker and more matt colour might help to keep down reflections of idiot lights and so on?  I painted the inside of my scope room with "Galaxy Blue" masonry paint, but that's because it's ply, so the paint will help keep out the dew and so on.

James

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