Astrokev

Not much to show over the last few days but I've been busy re-designing the ROR, when time allows. This is to increase the clearance above the warm room dividing beam. Hoping to start more construction this week ?

Your obsy's been up for several years now so clout nails clearly work just fine! Just checked out guttering. I think the mini-guttering should work fine. The full scale stuff looks huge and seems over the top for my little obsy!

That clearly works well and I guess I could've done similar. Rubber4roofs recommend using the adhesive though, so thought I'd follow their guidance to avoid risk of problems down the road - this roof is designed to outlast me and require zero maintenance! I seem to have loads of useful large offcuts already (I may have added too much size contingency!) so need to think of creative ways of putting it to good use. I'll probably end up putting it with all the other "useful" bits n bobs that I've collected over the years ?

Having done both I agree. The contact adhesive is a pain around the edges but getting the EPDM down and flat is fairly straight forward and easier than felt.

Collecting scopes is a competition between astronomers. The one who has the most when you die is the winner ?

Yeah, from your profile I can see that you are clearly a bit short in the scope department ?

Well I had to have a quick play with the C11 didn't I? And yes, it's lovely. Then I squeezed in an hour on the obsy. Finished sticking down the EPDM over the beam which means I can now start work on the rolling roof! Still a few bits to finish off on the warm room roof, but these can be done anytime - making holes in the EPDM on the beam facing the scope room to re-open the ventilation of the roof space; stick down the EPDM on the edges of the rails; fit battens at the rear and on the rail edges; trimming excess EPDM; fit guttering.

Haha. Sorry Neil, I didn't realise I had to complete the build in under 10 pages. I must try harder ?. I seem to recall Gina's build back in 2011 was over 45 pages ? so I have a bit to go yet ?.

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 ?

Thanks Mark. Yes really looking forward to starting the rolling roof too! Good luck with your build - be sure to post lots of pictures!

Haha ?

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....

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.

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.

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!

Speaking metaphorically of course ?

...and an air-con tube filled with a ton of concrete. My back is still aching!

Sounds like a plan. I guess the only risk is that the blocks may crack when drilling, but sounds workable.

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 ?

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.

Looking good. Interested in seeing how you will join these together.

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.

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 ?

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.

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?