Obsy build for the summer...

[fwm891]

I've been thinking about another obsy ever since we moved and I had to dispose of the last one. So I've been sketching out ideas, pinching ideas, looking at materials and finally come up with what I feel I can a) actually build, b) functional c) have permission form the boss to!

So I've attached my initial drawings.

The obsy building will sit on sleepers (having had to dig up the last lot of concrete foundations it's not something I want to do again).

Tri-pier / CEM60 with sit on a concrete pad under a suspended wooden floor

Walls are shiplap on 3x2 frames each of which is secured to a 4x4 corner post. OSB linings with insulation behind

Roof will be in marine plywood (with a covering to be decided on) and will run in a 'U' shaped track with 4 wheels per side. The track will be longer than the building width to give me a little more sky to the east.

 

Edited April 3, 2019 by fwm891
Door omited

[Yawning Angel]

Looks great! Best of luck with it!!

One thing I learned from a RoR build, Make sure the rails can't carry wet inside either on top or underneath. The best way would be to have a tiny degree of fall away from the scope room ? Both myself and @Astrokev had the same problem

[JamesF]

Weren't you living down this way at one point, Francis?  Or have I misremembered?

I reckon four wheels per side for supporting the roof is overkill, to be honest.  My roof is 3.6m long and must be approaching 150kg, but runs quite happily on two 80mm (v-groove) wheels per side.  Three per side would be belt, braces and left-over bit of baler twine as well.  I guess the roll-off is to the east because there's no option to have it to the north?

Definitely worth looking at EPDM as a possible roofing material (and if you use that you can get away with 11mm OSB for the roof structure rather than more expensive marine ply).  The fact that you can put it on as a single sheet makes leaks far less likely.  A few people (Alex?) have used a fibreglass finish in recent builds too.

As others have done, I reckon putting breathable membrane behind the cladding is a good plan.  It made life much easier for me having the place dry inside before I'd even had a chance to start getting the cladding on.  Put on with a staple gun it goes up very quickly, too.

I look forward to seeing how it progresses.

Oh, don't forget a door :D

James

[Yawning Angel]

12 minutes ago, JamesF said:

A few people (Alex?) have used a fibreglass finish in recent builds too.

As others have done, I reckon putting breathable membrane behind the cladding is a good plan.  It made life much easier for me having the place dry inside before I'd even had a chance to start getting the cladding on.  Put on with a staple gun it goes up very quickly, too.

Fibreglass reinforced liquid, in my case

Stainless staples for the membrane. Actually, stainless for every fastener ?

Edited April 3, 2019 by Yawning Angel

[JamesF]

I went cheapskate for the staples and used zinc coated ones :)

Actually, mostly it was cheapskate because we had them already.

James

[fwm891]

27 minutes ago, JamesF said:

Weren't you living down this way at one point, Francis?  Or have I misremembered?

I reckon four wheels per side for supporting the roof is overkill, to be honest.

Oh, don't forget a door

James

Hi James - Yes. I was in North Devon near South Molton but have moved to Hereford now. Your build is one that I've pinched a few ideas from.  I thought 4 per side because I intended using rubber wheels to keep the noise down when opening/closing the obs. The obs will be built parallel to and quite close to a neighbours house/fence along the north side. I won't have any view of the north sky so PA will be by other means although once set it should be a periodic check/adjustments.

I put the wrong image up first - there is a door between the track extensions...

EDPM is at the top of my list at the moment but would like something that doesn't heat the obsy up. My last one had a reflective ali sheet with Cellotex  insulation stuck to its underside - killed condensation.

Francis

[JamesF]

Interesting idea about the Celotex in the roof.  If I find mine gets hot in the sun perhaps I'll look at putting some 25mm insulation under the OSB.

If the wheels and tracks are true I've not found them to be noisy at all.  Probably the loudest noise when it's opening or closing is me grunting when I start it off moving :D  It's a different game if you've got near neighbours though.  For the small amount extra it might cost for the additional wheels it pays to keep them on-side and avoid waking them up in the middle of the night...

James

[Astrokev]

 

Agree with everything James and Alex said!

My roof has 3 wheels per side, the middle ones to remove any risk of the roof beams sagging in the middle. 2 per side would have dealt with the weight no problem. 

Mine are V groove wheels and track. Pretty much silent when rolling the roof off, so would strongly recommend these - I used Brundle like most folks. 

I highly recommend EPDM for the roof.

Good luck with your deliberations and build. Look forward to following it ?

EDIT - agree with Alex. Think carefully about how to prevent water getting in to the scope room through the gaps by the rails. Design this out before you start to build!

Edited April 3, 2019 by Astrokev

[fwm891]

Update

In the original drg's I never allowed for scope clearance when the roof rolled back. Doing this has meant moving the door to the opposite end (made it bigger too) and leave more of the end wall in place around the door.

I'm sure there will be other changes along the way...

TBC

[Davey-T]

My roof rolls on and off silently but the mount sounds like a screaming banshee when parking 

Dave

[Yawning Angel]

5 minutes ago, Davey-T said:

screaming banshee when parking

If that's likely to be a factor, then clearance to allow the roof to close without parking would help - I wasn't able to get my roof in under permitted development height guidelines, maintain my horizons and not bang my head, so the scope has to be horizontal before I can roll it closed. As with most things, it's a compromise.

I've 2 V rollers each side, from F H Brundle (sliding gate hardware) and it's very quiet when rolling

[fwm891]

The intention is to park the scope in a horizontal position, certainly the refractor. The Edge HD8 won't be a problem but I'd rather just have one park position regardless of which scope is on the mount. I like Olly's dual tec mounting but the only scope I have I would duplicate is the AA Wave Series 115... (dreaming again...)

[Swoop1]

That is quite an elegant solve to the scope height conundrum.

Allowing a taller door at that end with the shaped end wall profile- ?

[JamesF]

It is indeed a neat solution.  Looks as though you could probably have an A-shaped frame of timber running down from the ridge to the base of the rolling section of the wall that would match the profile of the cut-out in the wall and help tie in the base of the wall to stop it splaying outwards, which would be quite useful.

James

[fwm891]

My intention is to use plywood plates across each corner.

[Rusted]

Tracks on wheels makes more sense than wheels in tracks.

Upward facing channels are what is known as "gutters" in the trade. 

[fwm891]

Understand your thinking - tracks would never clog with leaves  and ice etc. But not as practical with a roll-off roof as it would require many more wheel pairs the entire length to the observatory and run-off beams. The  actual track would be shorter but for me that would be the only benefit.

[Gina]

Wheels ON tracks works well for me.

[fwm891]

Pondering whether to carry the cladding right across each elevation, mitre the corners and hide the corner posts...?

Edited April 6, 2019 by fwm891
text added

[laser_jock99]

On 03/04/2019 at 16:11, Yawning Angel said:

Looks great! Best of luck with it!!

One thing I learned from a RoR build, Make sure the rails can't carry wet inside either on top or underneath. The best way would be to have a tiny degree of fall away from the scope room ? Both myself and @Astrokev had the same problem

 Alternativley- don't use U-channel at all. Use outward facing L-section. No problems with rain/leaves/snow/ice.

You can see the L-section I used in this photo

[JamesF]

9 hours ago, fwm891 said:

Pondering whether to carry the cladding right across each elevation, mitre the corners and hide the corner posts...

Kev had a very nice-looking finish on his.  The corner posts were hidden, but a length of batten was fixed to each outside face and the cladding butted up to it.

He had a nice photo of it in his thread.  I'll see if I can find it.

James

[JamesF]

Hopefully this will link to the right place.

https://stargazerslounge.com/topic/295916-astrokevs-ror-the-build/page/18/?tab=comments#comment-3503957

It also reminds me of another good reason for hiding the posts, which is that a breathable membrane can completely enclose the shell of the observatory.  You can fix it at one side of the door and unroll it all the way around until you get to the other side.

James

[fwm891]

My earlier obsy while in Devon

Edited April 7, 2019 by fwm891
image added

[JamesF]

And you had to completely take that down when you left?

James

[saac]

On 06/04/2019 at 10:05, Gina said:

Wheels ON tracks works well for me.

And me, the depth of the track is too shallow to cause problems with water, ice or general clogging up. 

 

Jim