Recent Pulsar dome sighting?

[Rusted]

Hi,

I am in the process of demolishing my leaky DIY 2-story, 3m observatory.
See my profile if you are curious.

Now I am seriously considering a complete Pulsar 2.7m observatory sitting in my [rural] front garden.
Life is too short to build a new one myself and I may need it sooner than my usual DIY projects can manage.

The useful internal, size difference of the 2.7 is almost nothing.
Compared to my 3m plywood dome with internal ribs and base ring.
I use a long 6" refractor for Hi-res, H-a solar imaging.
So need all the cat swinging space I can possibly get.

There is almost nothing on Pulsar domes on YouTube within the last five years.
Recent images on European dealers websites show strange indentations in the Pulsar's walls.
Which to my [conspiracy theorist] eyes suggest a slight reduction in internal space.
Is this indentation to cater for fitting the equipment bays?
Or, some sort of AI/alien technology stiffening mechanism?

Has anyone actually seen or even own a recent example of the full Pulsar observatory?
I'd be very grateful for any feedback before I blow my life savings.
Please PM if you are shy about posting publicly on the forum.

Many thanks
Chris

[Shed9]

I'm not sure the newer design of the Pulsar domes eat into internal space with those indents, there are mating surfaces on the edge of each individual wall panel anyhow which take a few inches up on both old and new designs.  I agree that they are most probably there for strength as well.  I have a 2.2 and a 2.7 pulsar, albeit the older design, but do know someone who took delivery of a new 2.7m just last year, and they are very happy with it.  

[Rusted]

Thanks.

I suspected from browsing owner's builds online.
That the older Pulsar is a bit of an ongoing "project."

I heard that Pulsars are being produced on the continent now.
By a specialist GRP company using modern spray lay-up methods.
Presumably to a higher standard than hand lay-up.

Are yours mounted on concrete slabs or boarded bases?
I am a fan of pyramidal concrete carport post anchors.
Very handy for stability, easy leveling and getting everything off the wet ground.
No to mention easy isolation from the pier.
Concrete slabs are not always doable in a domestic garden setting.
I prefer to be able to walk away from a completely clean site after removal or demolition.

[Rusted]

When all else fails return to the source. Pulsar has updated its website since I last visited.
The drawings clearly show how the design has completely changed. No more simple dome quadrants.
There are numerous panels of different sizes. The walls are indented and the accessory bays are rounded on top.
The door is inset into the wall panel. Presumably offering greater weather resistance and stiffness.

 

[Alan White]

I can see why you are drawn to a Pulsar dome, I presume at ground level or will this be destined to sit high up?

The new design is very different to the former ones and the finish on the gel coat looked superb, 
I had wondered if the moulding had been done by someone else….i have not a clue on this of course.

I await the next move you make, but being set up and observing again I am sure will be a very positive thing.

[Rusted]

Thanks Alan. 

The new design has a very different look. Call me old fashioned but I might have preferred the simplicity and cleaner looks of the original. Even if it was structurally weaker in design. I have printed off the drawings and instructions. A truly flat assembly surface will probably pay dividends in functionality. So the floor had better be the first priority. To give me something to work on. Then the dome and walls will be true by the time the adhesive/sealer cures on the panel joints. Offering smooth rotation and an absence of binding. A dinky little toy compare with my struggles with the 4.3m dome!

[Shed9]

To answer the question on what base I used for my Pulsars, I went all in with concrete and lots of it.  I poured the pier foundations with essentially five foot concrete pillars and then poured the bases (isolated from the pier foundations) using cheap pool frames to maintain the concrete in a round form.  I probably overdid the concrete and used way more than I needed.  Another thing I did was to build one brick high round bases to mount the observatories off the floor to avoid water seeping in and provide a very precise & level base.

I would advise contacting Pulsar direct to pick their brains, both my domes were bought from the original owners but Pulsar were helpful over email when I needed that help.

[scotty38]

1 hour ago, Shed9 said:

Another thing I did was to build one brick high round bases to mount the observatories off the floor to avoid water seeping in and provide a very precise & level base.

I didn't do that with mine but it is on my to do list, well it's been on almost a year now 🙂 I never have managed to seal it properly with silicone etc....

[Oddsocks]

13 hours ago, scotty38 said:

I didn't do that with mine but it is on my to do list, well it's been on almost a year now 🙂 I never have managed to seal it properly with silicone etc....

I had the same problem with my 2.2m Pulsar dome, the silicone sealant bead around the outside perimeter of the wall-base junction would not stay bonded to the concrete, even though the concrete had been surface sealed with an exterior grade acrylic polymer before the dome was erected.

Solved the problem eventually (single handed) by taking the anchor bolts out of the wall flanges and using tyre levers and blocks was able to lift the entire observatory off the ground a section at a time, just enough to feed a length of 50mm wide by 5mm thick expanded silicone rubber strip under the wall to make a wide seal between the wall and concrete base.

Moving around the perimeter a metre at a time and just levering the observatory up no more than a 1cm, whole job took just an hour.

The expanded silicone strips I used were only available in 5 meter lengths and so had to be installed as two separate halves and at the joins I overlapped the sections by around 100mm, no glue needed, when the weight of the observatory presses down on the join the two sections flatten and seal nicely.

Once the anchor bolts were back in place the last job was to run a new bead of exterior silicone rubber sealing compound around the outside wall, but this time the compressed expanded silicone rubber seal under the wall lifts the dome wall off the concrete base to leave a gap of around 2mm high and an undercut of around 5mm, and the silicone rubber sealing compound can be squeezed under the wall and fill the gap.

Over the next weeks and months the expanded silicon rubber strip compresses even more, squeezing into the irregularities in the concrete and pinching down on the external silicone bead to form a really tight water-proof seal.

Did that job five years ago and never had any water seeping under the walls from the outside since.

Obviously would be a much simpler job to do before the observatory was erected.

The expanded silicone rubber strip is quite expensive in these sizes and I think I paid around £60 for 2 x 5 meter lengths, bought from Delta Rubber in Christchurch, Dorset:

https://shop.deltarubber.co.uk/rubber-strip/sponge-rubber-strip/expanded-white-silicone-strip-foam/white-expanded-silicone-strip.html
 

Edited Thursday at 12:26 by Oddsocks
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[Rusted]

Deleted.

Edited Thursday at 04:18 by Rusted
Added image

[Rusted]

 I just wrote a long response and decided to add an image under Edit. The whole thing has disappeared!

Now it won't let me Delete.

[Rusted]

Given your position on a rough slope your decision to use so much concrete was wise. There must be huge volumes of run-off coming down that hill!

My solution is to use carport anchor blocks with adjustable brackets. I used them on my two storey observatory and matching pier with great success.

The brackets on the buried blocks are shown in a 60cm concrete pipe I intended as a pier base. I changed the pier design to a plywood clad pyramid with feet at the perimeter of the 3m Ø building. I had to cut out a dog's kennel in the cladding to allow me to climb up through the pier.

[Rusted]

I have shown this early image of the basic structure several times:

[Rusted]

3 hours ago, Oddsocks said:

I had the same problem with my 2.2m Pulsar dome, the silicone sealant bead around the outside perimeter of the wall-base junction would not stay bonded to the concrete, even though the concrete had been surface sealed with an exterior grade acrylic polymer before the dome was erected.

Did that job five years ago and never had any water seeping under the walls from the outside since.

Obviously would be a much simpler job to do before the observatory was erected.

The expanded silicone rubber strip is quite expensive in these sizes and I think I paid around £60 for 2 x 5 meter lengths, bought from Delta Rubber in Christchurch, Dorset:

https://shop.deltarubber.co.uk/rubber-strip/sponge-rubber-strip/expanded-white-silicone-strip-foam/white-expanded-silicone-strip.html
 

An excellent and practical approach! One I would have thought Pulsar might have developed.

I imagine channel rubber seals on 1960s kit car/boat hatches as being suitable for this. It came in long rolls too.

[scotty38]

22 hours ago, Oddsocks said:

I had the same problem with my 2.2m Pulsar dome, the silicone sealant bead around the outside perimeter of the wall-base junction would not stay bonded to the concrete, even though the concrete had been surface sealed with an exterior grade acrylic polymer before the dome was erected.

Solved the problem eventually (single handed) by taking the anchor bolts out of the wall flanges and using tyre levers and blocks was able to lift the entire observatory off the ground a section at a time, just enough to feed a length of 50mm wide by 5mm thick expanded silicone rubber strip under the wall to make a wide seal between the wall and concrete base.

Moving around the perimeter a metre at a time and just levering the observatory up no more than a 1cm, whole job took just an hour.

The expanded silicone strips I used were only available in 5 meter lengths and so had to be installed as two separate halves and at the joins I overlapped the sections by around 100mm, no glue needed, when the weight of the observatory presses down on the join the two sections flatten and seal nicely.

Once the anchor bolts were back in place the last job was to run a new bead of exterior silicone rubber sealing compound around the outside wall, but this time the compressed expanded silicone rubber seal under the wall lifts the dome wall off the concrete base to leave a gap of around 2mm high and an undercut of around 5mm, and the silicone rubber sealing compound can be squeezed under the wall and fill the gap.

Over the next weeks and months the expanded silicon rubber strip compresses even more, squeezing into the irregularities in the concrete and pinching down on the external silicone bead to form a really tight water-proof seal.

Did that job five years ago and never had any water seeping under the walls from the outside since.

Obviously would be a much simpler job to do before the observatory was erected.

The expanded silicone rubber strip is quite expensive in these sizes and I think I paid around £60 for 2 x 5 meter lengths, bought from Delta Rubber in Christchurch, Dorset:

https://shop.deltarubber.co.uk/rubber-strip/sponge-rubber-strip/expanded-white-silicone-strip-foam/white-expanded-silicone-strip.html
 

Nice work and to be honest if it wasn't for the fact I have a couple of bumps when my dome turns I'd probably give this a go. As it happens I decided to take it down, do the brickwork and then really make sure it's perfectly level and circular. Having done it once I sort of know where I rushed first time round.....