Astrokev's ROR - The Build

[nightvision]

 If you are height restricted (2.5m) you may not be able to increase your yellow beam size to 150x22.  You might see some distortion of the yellow beams over time.  You could consider using some carbon tape and resin between the yellow beams and also do a little pre-stressing while the resin sets.  It would be even better to use 4 x  100x22  with carbon laminated between each beam.  This would probably do the job: Carbon tape.  You would also need some laminating resin .

 

 

Edited June 12, 2018 by nightvision

[Gina]

I have a similar design but with a higher apex and have had no problem of that sort.  What could be on the roof and fall off into the scope room anyway?  Mind you, mine has a gutter on the end away from the warm room roof.  Water from the sloping part over the warm room simply deposits rainwater onto the warm room roof and into the warm room gutter.  There are ridges on the sides of both roofs to stop water running off the sides.  Actually, because the ROR is wider than the warm room roof, there are short pieces of guttering to collect water from the ROR not over the warm room and deposit it onto the warm room roof.

[Astrokev]

15 minutes ago, JamesF said:

My slight concern about your roof design is that "stuff" can roll off it into the obsy whenever it's open or being opened or closed.  I might be tempted to put a raised lip on the end of the slope to deflect anything that has run down the roof to the sides.

I may, of course, be worrying about nothing

James

Thanks James. No, that's a fair point. Sadly, there's a biggish hedge to the West and a fairly tall Lailandii (both owned by next door neighbour) which tend to shed all kinds of rubbish. I gave this a severe trim last year and have just had another go at it, reducing the height a little bit more hoping that the neighbour won't notice, but there's only so far I can go! There's also a huge pine tree ~25m away which sheds needles by the ton at certain times of year.

I will be installing a gutter at the bottom of the slope which may help reduce the risk but I'll certainly give this some thought!

I think @yesyesused this design, so would be good to hear from him when he's next on the thread?

[Astrokev]

9 minutes ago, nightvision said:

 If you are height restricted (2.5m) you may not be able to increase your yellow beam size to 150x22.  You might see some distortion of the yellow beams over time.  You could consider using some carbon tape and resin between the yellow beams and also do a little pre-stressing while the resin sets.  It would be even better to use 4 x  100x22  with carbon laminated between each beam.  This would probably do the job: Carbon tape.  You would also need some laminating resin .

 

 

Thanks nightvision. That sounds an innovative approach. I've not heard of carbon tape so must do some research ?. I'll also relook at the dims of the beams; I may be able to increase these slightly.

[Astrokev]

10 minutes ago, Gina said:

I have a similar design but with a higher apex and have had no problem of that sort.  What could be on the roof and fall off into the scope room anyway?  Mind you, mine has a gutter on the end away from the warm room roof.  Water from the sloping part over the warm room simply deposits rainwater onto the warm room roof and into the warm room gutter.  There are ridges on the sides of both roofs to stop water running off the sides.  Actually, because the ROR is wider than the warm room roof, there are short pieces of guttering to collect water from the ROR not over the warm room and deposit it onto the warm room roof.

Thanks Gina. Yes, mine will have a gutter on the south end which will hopefully prevent water getting in when I open it, and may also catch other bits of debris. I must give this some more thought though to make sure I position the gutter correctly to act as a trap.

Regarding the risk of the apex beam deforming, I'll relook at the clearance. I may be able to increase this slightly, although I think I'm pretty close to the 2.5m limit ?

[nightvision]

Be careful when adding or laminating more lateral thickness to your end supported beams, this will add more weight and not a lot more resistance to long term flex.  Thinner taller beams if they can't move laterally will be stronger and lighter, laminating thinner beams with carbon will save weight and increase rigidity.

[JamesF]

Good point.  Increasing thickness doesn't increase rigidity anywhere near as much as increasing depth.  However, you could perhaps use some steel or aluminium bracing?  Perhaps a piece of angle iron or similar screwed or bolted to the inside of the timber?

James

[Astrokev]

7 minutes ago, JamesF said:

Good point.  Increasing thickness doesn't increase rigidity anywhere near as much as increasing depth.  However, you could perhaps use some steel or aluminium bracing?  Perhaps a piece of angle iron or similar screwed or bolted to the inside of the timber?

James

Yes that's a thought. I did that many years ago to increase the rigidity of a kitchen worktop that spanned a washing machine and tumble drier! Worked quite well as I recall.

[Yawning Angel]

Could upgrade to C24 grade timber for the roof....or even swap out for oak on select parts, giving more strength for the same dimensions ?

[yesyes]

22 hours ago, Astrokev said:

I think @yesyesused this design, so would be good to hear from him when he's next on the thread?

I've not had anything fall in from the roof (maybe the odd tiny leaf that I didn't notice) and I don't open it when it rains or just after rain when it's still wet. I've not seen a problem with this yet. But it may be different in different surroundings.

The alternative is to have the apex rotated 90 degrees, parallel to the roll-off direction. But in my case this would have made the building too high for the 2.5m limit. And I think the captive mechanism on the sides would look weirder ;-)

 

[Astrokev]

37 minutes ago, yesyes said:

I've not had anything fall in from the roof (maybe the odd tiny leaf that I didn't notice) and I don't open it when it rains or just after rain when it's still wet. I've not seen a problem with this yet. But it may be different in different surroundings.

The alternative is to have the apex rotated 90 degrees, parallel to the roll-off direction. But in my case this would have made the building too high for the 2.5m limit. And I think the captive mechanism on the sides would look weirder ?

 

Thanks Chris.  Have you noticed any deformation of the apex beam across the obsy due to the weight of the roof? I'm wondering whether I need to strengthen my beam and increase the clearance of this over the fixed beam separating the warm room and scope room. My current design has a clearance of around 30mm.

[Astrokev]

Well, the planets finally aligned and I laid the EPDM today. With hindsight I think it may have been better to choose a cloudy day. I initially took my shoes off to walk on the roof and when the sun came out the rubber was almost too hot to stand on (brought back childhood memories walking across boiling sand on the beach!).

The water based adhesive was fairly easy to work with, although it was a little too quick to dry in the mid-day heat. The contact adhesive was horrid, drying almost before I could get it off the roller or brush. Once I got used to how it handled I managed OK though.

First job was to fix the corner pieces (see several posts ago for images and logic for this). A bit tricky to slide the rubber between the roof and the side rails without the 2 adhesive coated surfaces touching until I was ready (manoeuvring 1.2mm rubber in a 2mm gap was a bit tight ?), but was surprised that I managed to get them fixed first time without problem. Images below. Once dry I trimmed the top edges then cut and stuck down the main sheet. The lower corners proved as tricky as I suspected and it took ages. By the time I'd finished in the early evening I was too shattered to remember to take pictures so will post these tomorrow.

Just a bit of tidying up to do and put up some kind of barge board along the rear edge. For the sides of the track rails, rather than use clout nails, I'm wondering whether to use an aluminium strip which would be thinner (than a timber batten) and may look more attractive than nails. Clout nails would work fine I guess so I must think about that one ? 

Edited June 14, 2018 by Astrokev

[yesyes]

41 minutes ago, Astrokev said:

Thanks Chris.  Have you noticed any deformation of the apex beam across the obsy due to the weight of the roof? I'm wondering whether I need to strengthen my beam and increase the clearance of this over the fixed beam separating the warm room and scope room. My current design has a clearance of around 30mm.

There is no noticeable deformation. Most of the weight of the roof isn't in the middle of that beam. It's more spread out. My beam is 100 x 50mm and the smaller sloping ones 50 x 50mm. There is 12mm OSB on top and then EPDM. No problems with deformation so far.

I do notice a bit of give and take in the timber depending on the weather (humidity mostly, I think). When it's been dry for a while the doors close a bit easier, for example. But that's expected with timber. You just need to account for that and not make things fit too tightly. ?  Doors for example but also that captive mechanism. I regret not spending more time aligning all that better before weighing down the roll-off roof.

 

[Astrokev]

10 hours ago, yesyes said:

There is no noticeable deformation. Most of the weight of the roof isn't in the middle of that beam. It's more spread out.

I do notice a bit of give and take in the timber depending on the weather (humidity mostly, I think).

 

That's a good point Chris. The total weight will be taken by the 3 cross-beams, each of which will be supported at the ends. Some of the load will therefore be directed down through the walls of the main structure, reducing the load in the middle span of the cross-beams. There's probably an engineering formula to calculate the load in the middle but that's a bit beyond my knowledge. I used the same technique with a garden shed rebuild a few years ago and the apex beam can easily take my full body weight. I'm probably worrying unduly, but may redesign anyway just to be sure. Overengineering - I love it!

[Astrokev]

Here's the progress from yesterday - and a bit of tidying up today.

All surfaces glued down except for the fixed beam separating the warm & scope room (I'll do this tomorrow), sticking the EPDM to the sides of the rails, and then trimming the excess. I'm quite pleased with how the corner pleats turned out. Acid test will be to pour a bucket of water over it to check no water can get in.

Haven't decided what to do about battening yet. The more I think about it, a piece of aluminium bar across the rear of the roof would act as a good drip-bar and would outlast a wooden batten, so may go this route. Also need to erect some guttering. I didn't think of this when I was designing my build, which focussed mainly on the woodwork, so I may need to be creative as I haven't got a vertical surface to attach the gutter brackets where I need them. I'll need to fabricate something suitable.

 

 

[yesyes]

This looks great so far! ?

Here is a photo of how I dealt with glueing the EPDM over that fixed beam. I only glued the bit upward where that piece of timber touches. The top and down on the scope room side I glued later when the first bit had set and the timber and clamps were removed. This made it easier to get it straight.

This would probably be good to use the contact adhesive for.

Edited June 14, 2018 by yesyes

[JamesF]

That looks very nice, Kev.

James

[Astrokev]

2 hours ago, yesyes said:

This would probably be good to use the contact adhesive for.

 

Thanks Chris. Yes, I've used contact adhesive to stick ~100mm around the edges of the "flat" section of the roof, and also for the track rails. It sticks instantly, so you have to be really careful when mating 2 surfaces. Get it wrong and your stuffed! It therefore doesn't need clamping. I've found that finger pressure and then using a small roller does the job nicely. I intend to use it for the fixed beam also, as you suggest.

Edited June 14, 2018 by Astrokev

[Astrokev]

Couldn't face doing any more EPDM work this evening, so decided to nibble away at a few jobs inside the observatory instead.

One satisfying job was to seal the warm room roof insulation with foil tape. Looks a lot tidier -  it's a bit of a shame that it will get covered up when I fix the ply sheet to the ceiling! Here's a before and after shot....

 

[JamesF]

Steady on.  If you make it look any nicer you won't want to put up a ceiling.

James

[Astrokev]

5 minutes ago, JamesF said:

Steady on.  If you make it look any nicer you won't want to put up a ceiling.

James

Haha ?

[Markh68]

Great build so far Kev been following it keenly since the start. Cannot wait until you build your rolling roof.

Planning to do a build myself very soon and your build along with many other great builds on this forum have given me plenty of ideas and inspiration.

[Astrokev]

5 hours ago, Markh68 said:

Great build so far Kev been following it keenly since the start. Cannot wait until you build your rolling roof.

Planning to do a build myself very soon 

Thanks Mark. Yes really looking forward to starting the rolling roof too!

Good luck with your build - be sure to post lots of pictures!

[Markh68]

1 hour ago, Astrokev said:

Thanks Mark. Yes really looking forward to starting the rolling roof too!

Good luck with your build - be sure to post lots of pictures!

Thanks Kev. I will try to remember to post lots of pics

[Astrokev]

In a bit of a dilemma.

Just picked up a nice shiny second hand C11 and Moonlite focusser. ?

So, do I do some more work on the observatory while the weather's nice, or play with the new toy ?