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Well here it is - the new Obsy

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Anthony Rodda's picture
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Well here it is - the new Obsy

Thanks for all the advice from people who responded with tips earlier. I've completed the new roll-off and it's 'operational' with the C925+CGEM reinstalled and room for another tripod mounted scope (hopefully a CPC925).

A 9x8 pent roof shed with an added internal frame bolted to the concrete base. Couldn't get planning permission from Mrs R for a permanent roll-off frame so decided on a folding 'gate' frame that naturally extends the 7° slant of the roof. 'Fencing' wire with tensioners across the gate diagonals hold it perfectly square but allow easy folding. Aluminium 'L' rails with 10 x 40mm castors on each roof side and central inverted castor guides (on the roll-off side wall) that pass-through two central batten supports on the roof, ensure accurate roll off/on for the 20 castor wheels. The 'gates' also have alu rails that interlock with the side rails when opened. The roof has a plastic/rubber membrane cover instead of roofing felt to save weight. It takes 30 seconds to open/close and moves with fingertip pressure. Chuffed.

And, most importantly, my wife is happy.

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Roofing material

That looks a good job Tony I'm in the process of building a 4.2m x 3.6 m roll  off  housing an 16" F:6 Newt/ME  as a 2nd observatory to my domed C14 Edge/MEII.

Could you provide the details of the roofing material you used-I'm looking for something other than felt

Anthony Rodda's picture
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"EasyTrim"

Hi Eric,

Wow, that area would be a fine weight if felted - getting on for 40kg?

This stuff is called Easy-Trim.  Make sure you buy the Non-Breathable (ie fully waterproof) variety.  There's about 20 stockists in Tyneside (such as Dove and Eurocell) so you'll find it anywhere.  It's in 45m rolls of 1m width and costs about £20 per roll.  It's literally 1/20th the weight of felt.

https://www.easy-trim.co.uk/products/roofing-underlay/breather-membranes...

You'll get funny looks from the builders when you ask for the Non-Breathable because the norm is to use 'breathable' under the likes of tiles/slates.  

I hurriedly nailed a covering on the roof at the end of the day just to keep things waterproof and it survived the last 'hurricane' without so much as a 'flap' or tear.  The first covering is still on. I've got 30m left!

Not sure what snow and Ice will do but I'll probably put another layer on and then see.

Regards

T

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motorise

Yes Tony,  there will be a fair bit of weight in the roof, hence trying alternatives to felt.  If the weight of the roof does become too much to easily move then I shall consider using some form pulley system of motorization  via automatic gates system.

Erioc

Anthony Rodda's picture
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Auto gates mechanisms

Hi Eric,

Yes I looked at those auto gate mechs in case I needed them.  A bit expensive for what i wanted.  I've knocked up a pulley/weight now and it works a treat.  Virtually no effort needed.  I'd go that route first.

Regads

T

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Roof

Love the fold in roof support.

How much does the roof weigh? Is it difficult to get back into place at the end of the night?

Anthony Rodda's picture
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Only about 50Kg all in.

Hi Grant,

Without the need for roofing felt (which would have added another 20Kg!) it's less than 50Kg including the barge boards.  Which I don't think is bad. The weight was bumped up a bit by extra wooden battens for bracing and, of course, the castors, etc. But nothing dramatic.  The roof height was only raised about 3 inches.

The whole thing is easily manageable.  I can push it up the 'slope' single handed - and I'm 5' 4" and 10.5 stone dripping wet. Left to its own devices it'll roll slowly down on its own. The slope is only about 7 degrees.  Enough to avoid standing water but not so steep so as to cause weightlifting type effort to get it back.

I've already rigged an old 10Kg counter weight vertically on a pulley inside the shed which almost negates any effort.

Literally 30 seconds to close and secure (once the mount is 'homed') and another 30 to close the 'gates'.

I need to give a bit of thought to the rear barge board which, because of the need for a good weather seal, just clips the rear wall as it goes over the top.  I can't decide on a hinged board or just a rubber trim but since I haven't yet had any water ingress despite several heavy downpours I might just leave it be.

My only issue is what to do with the water that runs off the front during rain!

Regads

Tony

Andy Wilson's picture
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New Obsy

Looks fantastic Tony! Ready in time for the long Winter nights. All we need now is plenty of clear skies.

Cheers,

Andy

Anthony Rodda's picture
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Please, please, please,

Yes Andy, the one thing lacking!  Desperate to get back into the swing.

Regards

T

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Well here it is - the new Obsy

It looks very fine. But it seems that the house is blocking a part of your horizon. Which way is south?

Lars

Anthony Rodda's picture
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The house is North

Hi Lars,

The house is North - although what you see is mostly a single story garage.

My views East and West are particularly good.  West is the Northumberland National Park (great!) but East is light polluting Newcastle.

South is good above 20*.  I don't miss much North.  I can see Polaris and anything circumpolar above 65*.

Regards

T

Roy Hughes's picture
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Had a look at the data sheet

Had a look at the data sheet for the roofing material you used and it states "UV stable for 3 Months".

Looks a bit iffy for this application.

Roy.

Anthony Rodda's picture
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mechanical performance

hi Roy, yes, its limited somewhat by the UV restriction. i've mitigated against any mech failure by using exterior varnish on the roof underneath and i now have two layers of poly covering in place. if the first does crack or become porous the layer underneath should hold (and should be UV protected by that above). The weight saving and cheap cost is worth it.  It took ten minutes to cover the roof.

there's some good rubber roofing products out there too so i'll watch the performance of the Easytrim and keep the forum updated.  let me know if you find anything better.

regards

T

Anthony Rodda's picture
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PS

Hi Roy,

I'd looked carefully at rubber membrane based roofing options but these were very expensive (£100+) compared to the £3.50 and ten minutes work per covering for the EasyTrim.  

Regards

astrotom925's picture
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New Obsy

Great job Tony.

The fold in roof supports are clever. I think you had similar issues to me regarding the large foot print of a standard roll off design. I have attached an image of my solution.

I'm sure you will find working from the observatory will be far more rewarding.

Good luck.

Tom

Anthony Rodda's picture
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Nice one Tom

I'd considered a folding design but my flat roof is approaching 9x9 for which weight is an issue and I couldn't guarantee rainwater wouldn't stand without some form of artificial slope.  (I didn't really have the room for (half) a fold-off on neighbours' sides).

Those ropes must be strong! 

Good visibility though.

Regards

T

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Pier

Tony,

where did you get your pier from?  Looks substantial and I'm looking for one for my Paramount ME II.  Their offer is ridiculously priced.

Cheers

Eric