New roll-off roof obsy build

[vincentnm]

For the past 6 weeks or so, I've been trying to reach many of these Wooden Observatory suppliers/builder, but to no avail. Some reverted politely saying they have a 3-6 month backlog, and some did not even bother to return calls, whatsapp messages, emails. So I bit the bullet and decided to build one.

Intend to house 2 x EQ6. Slightly largish build 4.5m x 2.5 m (15 x 8 feet). 7x3" treated timber for the structure, Oriented Strand Boards for walls and roof, castor wheels, and aluminium railing. 

Here's my plan and elevation. Will post photos as the build progresses. 

[Swoop1]

Brilliant! Another obsy build thread to enjoy. I look forward to your prgress reports @vincentnm

[Robindonne]

If this hobby continue to attract me for the next couple of years (dont know why it won’t😅) i would love to build one my own some day.  So yes, very nice to see the progress of yours. I love working with (hard)wood but im not sure if its my preferred material for the construction.  Maybe im wrong but i always have the feeling a long “sliding roof” construction will always be a bit wobbly because the walls will never be hard connected to each other.  My future astro-shed will likely be build around metal poles attached to a concrete foundation/floor.  
The uk probably has very much the same sort of construction materials as we have in NL, and if so, maybe take a look at screwpoles? If you dont have a solid concrete foundation.  Ill add an image.  

Whatever method you use, im looking forward to follow the progress😍

Edited June 1, 2021 by Robindonne

[MikeP]

One simple piece of advice I would offer at this stage - make sure there is a slight slope on the runners towards the open area.  Dead level is pretty much impossible to achieve and if it slopes the other way, you'll have to find a way to prevent little dribbles of rain running in.  How do I know?  Please don't ask.

Good luck with the build.  Are you anywhere near TN8?

Mike

[nightster]

Your design shows caster wheels. I recommend V groove metal wheels with inverted Angle Iron steel drilled and deck screwed to wall headers as the track. Friend of mine used C channel and synthetic caster wheels and the channel would cut into the wheels after a year of settlement around structure and made the roof very difficult to move. Suggest putting wheels on bolts as axels with some amount of play between the hubs and the wood that they are attached to to allow them to float left or right as the roof moves. Also use wheels with roller or pin bearings to reduce friction.

[skyhog]

I built a roll off roof obsy nearly 17 years ago and it's still going strong. I built it with in lot of haste as I realised very quickly the 12 inch lx200 I'd bought was either going to be sold or used very rarely. The whole thing is wood. I did intend to use metal V track and so on eventually and had the intention of adding a motor to open and close the roof. The fact is that it worked fine and has done since I built  it. The 8 large rubber wheels trundle up the square section wooden channel just fine. We are not talking fine engineering here, they find their own path and everything works out OK. I can supply a few pics if anyone is interested. 

[abberation]

I would be interested to see a couple of photos of the wheels/channel and also how you have locked the roof closed when not in use.

[AMcD]

I second the advice about not using channels if going for metal runners.  I had castors in aluminum channels originally and if the roof moves slightly from the centre line after repeated use the wheel assemblies can bind against the edge of one or other channels, making it harder to move.  I am about to install a Talon6 roll off roof opener on my observatory as part of an ongoing project to achieve remote control.  When I upgraded the wheels and railings in anticipation of this development the supplier advised me to install grooved metal wheels running on a track on one side and hard nylon wheels running on flat metal on the other side.  This way, the roof will not be at any risk of binding (and stalling the motor) if the observatory has shifted / settled slightly out of true in the 15 years since it was constructed.  The new set up is much, much smoother than the old one and much easier to move.

[AMcD]

I also upgraded the external frame with aluminium joists  as after 15 years the wooden ones had rotted through.  I had to reinforce them with steel framing underneath to be certain that they would take the weight of the roof (they have not bent so far).   Bracing the frame with corner joists at the end is also a good idea as this makes it far stiffer.  

 

[AMcD]

With respect to the rotted parts of the frame, I suspect I was only a few openings from disaster...😳

 

[nightster]

I dont have a closeup of the angle iron used as a track, can grab one next time Im down there. Here are 2 pics showing way to secure roof for different reasons. First, we have 4 latches that simply tie down each corner when roof is closed and we are not planning in using it. Or if a strong extended storm is forecast. The shed has already taken a 40+mph short duration thunderstorm with latches not secured. The second pic shows another use of angle iron. This time, 1.5x1.5” angle is screwed to walls parallel to roof movement. 6 short 3x3” sections of angle are screwed to rolling roof. These are placed in an interference orientation so that roof will slide south to north but any wind or upward movement of roof causes the angle to touch dissallowing further separation. If that makes any sense…If not I can get more detailed pics/video later.  Also note on the interior latch pic the galvanized roll steel we used under the pressure treated top board(which is what the inverted angle iron is screwed to to make the track) which will keep moisture away from the non-pressure treated portions of the wall headers. Also see the steel v track wheel hiding to the right bolted in place between the roof “trucks” as we called them. 

Edited August 9, 2021 by nightster

[r3i]

On 04/06/2021 at 13:51, nightster said:

Your design shows caster wheels. I recommend V groove metal wheels with inverted Angle Iron steel drilled and deck screwed to wall headers as the track. Friend of mine used C channel and synthetic caster wheels and the channel would cut into the wheels after a year of settlement around structure and made the roof very difficult to move. Suggest putting wheels on bolts as axels with some amount of play between the hubs and the wood that they are attached to to allow them to float left or right as the roof moves. Also use wheels with roller or pin bearings to reduce friction.

I used castor wheels and a C channel on my build and 8 years later it's still working well, apart from the channel getting clogged with ice on those thankfully rare occasions when we get heavy snow.

Having said all that, if I was to build another observatory in the future, I would go for the V groove metal wheels as by all accounts, they give a smoother running action.  Probably more pricey though than casters.

 

[malc-c]

This time 10 years ago I was in the middle of building my observatory.  There are a few things I would do differently, but on the whole I'm happy with how its lasted.  Based on my experience I would offer the following comments based on the original drawing above.

Framework.  -  Depending on your location, you need to take into account snow.  I've had occasions where a good 9-12" of standing snow settled on the roof, so the structure needs to be sound.  I built the framework of my observatory to standard 16" centres.  It's a solid construction and takes the weight of the roof, even when covered in snow with ease.

Runners - I used rubber castor wheels, around 5 each side, with only one side set into an aluminium U channel track.  These have shown no signs of perishing and still function fine to this day.  They also run quiet compared to metal wheels on metal track... something worth considering when you are closing up at 3 or 4 am.

Material - Don't use OSB - use ply, and exterior grade if possible.   I used OSB on the warm room, and due to a lack of fall on roof water creeped up under the felt and it soon needed replacing.

Screws - Don't use nails to make the framework.  Use decent length screws.  It makes for a sound and sturdy structure.  When joining two walls together I used sunken coach bolts.

Over the years the observatory has been exposed to 60 mph winds, torrential rain, heat waves and foot or two of snow, and its still standing

 

Edited August 11, 2021 by malc-c