Astrokev

Thanks Ray ? One less thing to do then!

A random question to all the FH Brundle users out there - should I grease or lubricate the track at all, or leave it dry? The wheels roll smoothly as it is but wondered if lubrication would improve performance further or help prevent the track oxidising over time? Thanks.

More playgroup fun with my grandson today so not much time working on the observatory. Did manage to complete the second wheel beam this evening though, which I was pleased to finish. Also started to measure-up and align the V-track on the walls but light was fading by this time so this will have to wait until tomorrow (after I've had a visit from my local plumber to have another look at my broken showers ? ). I've realised I would benefit from making a jig to get the spacing of the 2 tracks accurate across the width of the obsy. As most of the width is fresh air, simple measurement using a tape is tricky and prone to error I think. I'll be much happier, and it will probably be easier in the long run, making up a solid jig. So here's an exciting picture of two wheel beams ready to be raised to the roof ?

Think I'll stick to my drill and chisel. I'm lethal enough with that as it is without any further encouragement ?

In my experience you always need more cement and ballast than you think!

Crikey, d'you need a licence for one of those? ?

?. Never heard of one of those but sounds a serious bit of kit!

Here's the redesigned roof (minus most of the joists to aid clarity). Wheels are crudely shown as red blocks. Probably looks pretty much the same as the last SketchUp drawing I posted but the apex has been raised slightly to increase clearance above the warm room dividing beam. I've decided to also add a length of steel strapping on either side of the apex beam to increase rigidity (not shown in the drawing). Also not shown is the side retaining mechanism to stop the roof lifting. This follows the wrap-around design used by a number of other builds and I guess is becoming the standard method of preventing your roof ending up in next-doors garden!

Yes I was originally going to have 4 as these would easily take the weight at 250kg capacity each. My worry was the risk of the wheel beam sagging slightly in the middle as the wheel separation is quite big, and I've chosen to have the rail beams oriented horizontally and not vertically. The middle wheel will be directly under the supports for the apex beam, removing the risk of deformation. Aligning 3 wheels on a side is more challenging though, as you say, since the beam (and I note the track also!) aren't perfectly straight.

Why does everything always take 3 times as long as you expect? I did spend an age deciding what size screws, bolts etc I needed, and then visiting Toolstation, so that dragged things out a bit. In the end I opted for stainless coach screws for the track, since these will be exposed to the elements. It also took me a while to figure out the best way of cutting out the holes for the wheels. Could really have done with a router but had to make do with the cordless drill, rasp and chisel. Anyway, managed to finish the East rolling rail. The track isn't screwed down yet; I'll do this when both rails are complete and I've aligned the tracks to ensure they're parallel and square to the north dividing beam. Recommendations from other builders say to spend time getting the alignment as good as possible, so intend to do just that ? Have to say that the rail rolls so easily and smoothly! I hope it's the same when it's taking the weight of the roof and EPDM! In the first pic the rail is upside down!

Well, not a huge amount to show today but at least I've restarted construction, and significant in that I've finally started the rolling roof! Spent the morning playing with my little grandson ?, then in the PM I searched through over 30 lengths of timber and finally managed to find 2 that were not twisted, bent, damaged or split, to use for the wheel beams. I love Wickes! So didn't have much time to start sawing, but did manage to cut one hole for the first of the 6 V-wheels, 3 per side. Although not yet fixed to the beam, the pics below show the design I'm using. The last image is upside-down to show the wheel design for anyone unfamiliar with such things. I must say I like this wheel design, the weight of the beam and roof acting vertically on the fixings which feels very secure. My plan is to cut the 3 holes I need with a small amount of lateral play, and drill the bolt holes with similar lateral play (effectively short slots rather than round holes), to allow me to adjust the alignment as best I can before tightening the nuts on the bolts. Well, that's the theory, I suspect it won't go as smoothly as that! With good weather forecast for tomorrow, hopefully I'll get a few more holes cut ?

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.