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2.1 Pulsar Dome - An Observatory at last


sloz1664

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Well after months of debate and anguish on the choice of ROR or dome. I have plumped for a dome. Well, it was decided for me, really, as a Pulsar 2.1 Dome was advertised on AB&S for the price of materials to build a ROR shed. No contest. Sealed the deal and started on the base.

First I had to dismantle an 8x6 greenhouse "balanced" on a rotton wooden base. No photos as this was a necessity and not a labour of love .:icon_biggrin:

Had to cut through 8" concrete to create an aperture for the block of concrete to house the pier and mount.

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The cutout in the bottom right hand corner is a soakaway that was used in the greenhouse.

20160417_115608.jpg

It rained all the previous day which meant the hole was 3" deep in water. Threw a couple of bags of dry concrete mix in the hole and mixed it by hand. That sorted it :headbang:

1400 kg later the hole is filled and the pier studs set in position.

20160417_130509.jpg

Polystyrene barrier in place before pouring the top screed.

20160417_171948.jpg

Screed down and just waiting for the final polish.

20160417_120731.jpg

The Pier - Designed and made from 8" box section 10mm thick with welded 10mm plates top and bottom. All my own work.

20160417_120805.jpg

Pier Top - Designed for the EQ6 Mount. manufactured from 8" diameter Aluminium 30mm thick. Again all my own work.

 

I will be collecting the Pulsar Dome soon and will post my exploits, as and when

 

 

Steve

 

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I've got the old 4-section 2.1M Pulsar, some thing to consider:

Don't skimp on the sealant between the dome and the concrete, mine has failed under the doorway after 2 years.

Just waiting for a week or two of dry weather to dry things out and allow the new sealant to cure - some chance!

I got the walls and hence the track for the dome pretty near to a circle, but I don't think the dome is, so one of the wheels tends to fall off  if i forget to pull inwards while I rotate.

Get the pier offset right, make allowance for a guidescope on top of the OTA if you image.

Michael

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17 hours ago, laser_jock99 said:

Good work- just hope you have enough clearance around that square plate at the top of the pier?

I made my pier top minimally round to avoid clashing with the mount.

Dscf6720_1024_zpsbac071e2.jpg

I have drawn all my scope permutations on the mount & pier as 3d models in solidworks. There looks to be enough clearance, but until it's all built and functioning I won't be completely 100% sure. If there's an issue it will need a mod :)

Steve

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I collected my dome yesterday from a small village just inside Wales about 12 miles from Chester. The Dome had to be manhandled from it's present position and onto a 3.5 Ton flatbed truck. It took 3 men to get it on the truck and it was a strain, they are a lot heavier than they look :shocked::shocked::shocked:

The drive back to Nottingham was a little interesting especially driving through the centre of Chester. The looks we were getting, as we drove past, were a picture. I have to say Chester is a beautiful city.

Once back home offloading the Dome was quite easy, just slid it down two ladder sections propped against the rear of the truck. I removed the sliding aperture cover and the dome from the base and moved it into the garden by removing a fence panel.

20160423_162013.jpg

4 hours later the dome is stripped down and cleaned :)

Steve

 

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Excellent purchase - my Pulsar dome transformed my enjoyment of astronomy.

Unless it has already been done, now would be a great time to replace all the nuts, bolts and washers with stainless steel versions like those in the latest version. Once installed, you should literally be able to turn the dome section with your pinky it is so well sorted! Have fun.

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15 hours ago, steppenwolf said:

Excellent purchase - my Pulsar dome transformed my enjoyment of astronomy.

Unless it has already been done, now would be a great time to replace all the nuts, bolts and washers with stainless steel versions like those in the latest version. Once installed, you should literally be able to turn the dome section with your pinky it is so well sorted! Have fun.

Hi Steve,

I noticed the bolts were corroded and rusted whilst removing the side rollers to enable the dome to be separated from the base. Stainless steel nuts, bolts and washers are on the agenda. :)

Steve

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Just now, Grotemobile said:

Very good Steve. Like the bit about making your own pier & pier top.

Be interesting to see how it all pans out . :thumbsup:

Thanks Steve.

I'll let you know as and when things happen. If it wasn't for the SGL forum I would still be in the planning stage. For months to come. :icon_biggrin:

 

Steve

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Finally it's in position. All that's now required is:- Electrics, consumer unit, cat6 cable, alarm, new bolts, hinges and......... patience, lots and lots of patience. :help:

Dome.jpg

Like the inbuilt chimney on top to rid of the hot air when things go wrong :)

Steve

 

 

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  • 1 year later...

Hi,

Resurrecting this post as I’m just in the process of erecting my 2.1m Pulsar dome and have some questions.  I'm nearing the end of the project, 6" - 8" concrete floor laid with air-gapped 12" x 1m concrete pier put in over the last two weeks replacing an 8x8 greenhouse which had concrete footings - leaning concrete footings hence 6"-8.5" deep concrete added to infill it and level it off.  I finally put the roof on last night which was a challenge for a one man outfit but I digress.  It's not the youngest dome nor is the finish in prime condition but it's a start.

I don’t have any installation guides for this model – couldn’t find any online and my email to Pulsar a while back failed to get a response.  It’s a 2.1m (in green) looking just like yours if you still have it.  Even though its pretty straight forward to build it's the fine tuning I'm interested in. 

A few things are apparent on mine -
 
1. I cannot open the main obsy door if the roof is pointing 180 degrees from the doorway as the L-brackets that hang down on the rear of the dome roof which hold the roof bars over hang the door way. Is this normal?

2. The join between the roof panels directly overhead either side of the slot is completed using only sealant for the last say three inches because the mating flanges of each panel are cut back short from the centre (I guess to allow the wheels on the handle to roll by). Is this normal?

3. Roof slot opening is stiff/jerky, I've lightly lubricated the aluminium rails and gently bent them so that the cover doesn’t grate against the roof slot but it’s still difficult close once it has been fully opened - to the extent that it’s easier to get it started from the outside (I’m 6’1” and at arm’s length it’s hard to get enough weight behind the handrail).  The guide wheels on the handrail turn smoothly enough. I think the guide bushes may be worn or missing something - any close-up pics of the bushes would be appreciated.

4. There seems to be a fair amount of daylight light getting in around the aperture when closed directly above where the scope will be - I'm worried that it may not keep out driving rain without modification such as adding brush strips or rubber.  Maybe mine is missing a seal of some kind?

5. Rotation is pretty smooth but there’s a bit of tyre squeal which in the dead of night might not go unnoticed by my neighbours – any suggestions?  Maybe the castor rubber has aged or maybe they can be dressed with something to quieten them down.  Dome is on a purpose made level concrete base.

6. Gap between roof and body all round – have you filled that with anything?  I was considering using a dehumidifier but with that amount of gap I’d be drying the planet too. I'm thinking a deep foam skirt added to the roof panels to cover the gap might work and not get in the way of any moving parts?


For points 1 & 2 it 'feels' as if the dome was perhaps originally designed to have the L-brackets the other way up so as not to impinge on the doorway (it doesn't seem unreasonable to me to want to enter/exit no matter which way the roof is pointing).  The effect of this would also be the cover could then only open to approx half way (like some others do) but at least the flanges would be complete, but then maybe as an afterthought somebody modified the design by turning the brackets upside down and hacked off the ends of the roof panel flanges so that they could view zenith without having to mount the scope off centre.

I know these things cost a pretty penny back in their day but this just seems a little rough around the edges let's say (or perhaps 'quirky' is kinder).

I can’t wait to get my gear setup in there - nor can my missus who is fed up of walking around it in the house (it's 12" SCT on tripod with loads of associated gubbins), I just want it to be leak and squeak free before I do.

Any info would be greatly appreciated.  
 
Best Regards,
Paul

1 - starting off, 1m deep conical hole, kick guard inserted.jpg

2 - floor laid.jpg

3 - testing levels before pour.jpg

4 - 2x 25mm x 1.9m rebar added, underground cavern filled.jpg

5 - ready to fill pier.jpg

6 - filling pier.jpg

7 - inserting pier top.jpg

8 - sides up loosely.jpg

9 - dull roof.jpg

10 - polished roof.jpg

11 - built but not sealed.jpg

12 - pier neoprene wrapped.jpg

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3 hours ago, sonneyboy said:

Hi Paul


 
1. I cannot open the main obsy door if the roof is pointing 180 degrees from the doorway as the L-brackets that hang down on the rear of the dome roof which hold the roof bars over hang the door way. Is this normal?

The L-bracket extension is due to the Roof aperture being extended so you can view to the zenith.

2. The join between the roof panels directly overhead either side of the slot is completed using only sealant for the last say three inches because the mating flanges of each panel are cut back short from the centre (I guess to allow the wheels on the handle to roll by). Is this normal?

Can you take a picture of this issue. So I fully understand your issue.

3. Roof slot opening is stiff/jerky, I've lightly lubricated the aluminium rails and gently bent them so that the cover doesn’t grate against the roof slot but it’s still difficult close once it has been fully opened - to the extent that it’s easier to get it started from the outside (I’m 6’1” and at arm’s length it’s hard to get enough weight behind the handrail).  The guide wheels on the handrail turn smoothly enough. I think the guide bushes may be worn or missing something - any close-up pics of the bushes would be appreciated.

I have the same issue. I intend to modify my shutter to make it a lot smoother. Them motorise it.

4. There seems to be a fair amount of daylight light getting in around the aperture when closed directly above where the scope will be - I'm worried that it may not keep out driving rain without modification such as adding brush strips or rubber.  Maybe mine is missing a seal of some kind?

There are no seals on the Pulsar Dome. I do not have any light leak issues. Can you highlight the issues with photos.

5. Rotation is pretty smooth but there’s a bit of tyre squeal which in the dead of night might not go unnoticed by my neighbours – any suggestions?  Maybe the castor rubber has aged or maybe they can be dressed with something to quieten them down.  Dome is on a purpose made level concrete base.

I stripped all my wheels, replaced all the nuts & bolts with stainless steel equivalents and fully lubricated everything. Runs smooth now and no squeaks.

6. Gap between roof and body all round – have you filled that with anything?  I was considering using a dehumidifier but with that amount of gap I’d be drying the planet too. I'm thinking a deep foam skirt added to the roof panels to cover the gap might work and not get in the way of any moving parts?

No, it's amazing how well insulated it is. All observatories require some kind of air flow anyway.

If you have any other questions please do not hesitate to ask.

Steve

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Hi Steve,

See attached. Bear in mind I've not applied any sealant yet.  This pic shows the sections where only sealant will bridge the gap in the roof panels plus also shows the daylight entering under the roof panel.  Is this like yours?

Cheers,

Paul

IMAG9773.jpg

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8 hours ago, sonneyboy said:

Hi Paul,

 

No mine is not like that. The Shutter "running rails" are secured to the Dome. The Shutter slides on the rails using two nylon bushes. There is a little light leakage. But that's with the Shutter closed and, more importantly, it does not leak.

Regarding siting your Dome. I sat mine on a level concrete pad. I sealed under the outer flange with silicone. Laid a heavy duty DPM on the inside and sealed to the Dome walls with silicone and completed the floor with interlocking foam tiles. Nice, dry and no damp.

 

Steve

 

20170721_201049[1].jpg

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Hi Steve,

Ah I see there are big differences - how many pieces does your roof consist of?  Mine is in four quadrants hence that odd bit near the centre that i was querying.  If does sound like the mechanism works in the same way though and i suspect there is too much play in the bushes on mine to hold the top close to the roof when closed.  The bushes look like cable glands to me (possibly original?) but they are way oversized compared to the rails and i think this causes them to snag.  I've got a 3d printer so i reckon i'll try knocking up some alternatives to see if I can improve matters.  

 

Cheers,

Paul

glands.jpg

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Hi Paul,

My Dome is one solid piece and yes the Shutter runs on the rails with cable glands. I'm wondering if reducing the bore size may cause the Shutter to stick. I'm modifying my Dome to automate it, starting with the Dome rotation. I will be starting a thread depicting my exploits.

Steve

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Hi Steve, I'm thinking the glands might have once had a bush inside them which has deteriorated and that combined with the curvature of the rails as they pass along them means they now rub their two extremities on the rails causing this grabbing so I was thinking maybe reducing the contact area either by adding a narrow liner into the gland or redesign the gland. The oversized hole would explain why the gap between roof and cover is large when in the closed position, it would pull down a few mm if the fit were closer.  It is tempting to add some U-shaped rubber trim to the very back of the roof cover though and give it a hose test before I kit out the dome.

I'm looking forward to seeing your project.  I have been mulling over adding rotation to the dome (owned it since November but never erected it until this week so had plenty of cloudy nights to ponder) and given my body and roof is in sections it doesn't lend itself to many approaches due to the raised seams all over the place.  Adding a driven wheel attached under the roof edge with a couple of SLA batteries hung in the vicinity will likely be my approach (no wires needed to cross between rotating roof and base) and a pair of accelerometers/gyros, one clipped to the end of the OTA and the other fixed on the roof.  I'd simply drive the dome motor in whichever direction is required to put the opening in the most favourable position based on the OTA position. Wouldn't need encoders and the like then and you could even use it on scopes without computer control.  I'm sure the challenge will be correlating the two sensor positions.  Recharging the batteries could take place when the roof 'parks' after a session. My scope is 12" and the aperture on my dome is quite narrow so the least I should do is add a warning system to let me know its time to give it a manual nudge and that idea of accelerometers could do that without the drive - at least it would prove if the idea is sound or not with very little investment. All just ideas at the moment. 

Cheers,

Paul

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I'm going down the Levesdome project route. http://www.dppobservatory.net/DomeAutomation/DomeDriver.php. I have built all the electrics and it works ok. I am going to drive my dome using a toothed belt mounted onto a wooden shelf attached to the dome. It will be driven by a heavy duty windscreen wiper motor with positioning sequenced with a Mouser Encoder. The "wooden Shelf" will be segments spanning the 16 flats of the dome and fastened from the outside by stainless steel screws. The circumference in which the toothed belt will be attached, will be machined with a router attached "fixed" to the wall inner rim and slowly rotating the dome. After fixing the timing belt in position the Motor will be mounted to the wall inner rim, with the drive gear sprung loaded onto the belt. Hope that makes sense.:icon_biggrin:

Steve

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Steve, That's a nice solution - I like idea of the router machining the shelf in situ so you get the consistent spacing regardless of roof irregularities.  I did consider adding a plastic toothed track to the inside of my dome (queue the 3d printer and several weeks printing!) but the four roof seams put me off (you don't have that concern) however the idea of a wooden shelf like you are using would make that idea fly again - plus that shelf could span the roof to wall gap that I mentioned in my first post which seems excessive in my dome - I found a fairly large snail inside the dome tonight and it can only have got in through that perimeter gap as nowhere else is large enough.  

Cheers,

Paul

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  • 2 weeks later...
On 7/21/2017 at 23:59, sonneyboy said:

Steve, That's a nice solution - I like idea of the router machining the shelf in situ so you get the consistent spacing regardless of roof irregularities.  I did consider adding a plastic toothed track to the inside of my dome (queue the 3d printer and several weeks printing!) but the four roof seams put me off (you don't have that concern) however the idea of a wooden shelf like you are using would make that idea fly again - plus that shelf could span the roof to wall gap that I mentioned in my first post which seems excessive in my dome - I found a fairly large snail inside the dome tonight and it can only have got in through that perimeter gap as nowhere else is large enough.  

Cheers,

Paul

Hi Paul,

Re: Automating the Pulsar Dome. I'm going to stat a new thread regards this "challenge".

Steve

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