Astrokev

Today's progress -

1) Fitted the ROR North end beam. When the roof is closed this only clears the warm room roof by under a centimetre. This feels a bit close for comfort. However, if the beam starts to sag under the weight of the roof I can always shave a little off the bottom by completely opening the roof, at which point I can access the underside of the north end to modify or add a strengthening bar (I may do this anyway as a precaution). As I expected, when placed across the ends of the wheel beams, the north beam is not quite parallel to the warm room dividing beam, leaving a 1cm gap at the west end when the roof is in the closed position. I think this is due to the dividing beam not being quite square. Not a major problem but I've decided to move the west end of the north beam in by a centimetre to make it parallel and improve the "seal" when it's closed. This is hardly noticeable and will be hidden by the overhanging roof sheets when these are fitted.

2) Cut the two ridge beams to length, screwed them together and placed them in position ready to be fixed with brackets when I've got the brackets to fix them with ?. These clear the warm room dividing beam by the 54mm I'd calculated in SketchUp, which actually looks huge in the flesh! I could've gotten away with a slightly smaller clearance I think, which would have reduced the height of the whole building a tad. I'm very close to the 2.5m limit so need to be careful now.

3) As a temporary measure, I've fixed 2 diagonal struts to join the South beam to the wheel beams near the centre blocks, to keep the frame square (can't see these in the pics). I had to raise these on additional blocks so that they cleared the warm room dividing beam. I will have to remove them when I fit the rafters, at which point I'll figure out how to brace the frame more permanently. James' suggestion of putting a diagonal across the rafters is probably the favoured option right now, but I'll have a play once some of the rafters are cut.

The north, south and ridge beams all overhang the wheel beams by just over 100mm - this is to give me something to hang the roof retention mechanism off.

Boy, it was warm today!

Pics as usual....

40 minutes ago, JamesF said:

Regarding the rigidity of the roof, I think the way it's done on a "proper" cut roof is to have diagonal timbers fixed across the undersides of the rafters which is what I assume would prevent you opening the roof?

Could you get away with some of the strapping you used to fix the base on the concrete pads if timber would be too thick?

James

Thanks James. Yes, that's an idea. Once the ridge beam is on I'll be able to check the clearances (instead of relying on the theoretical clearances in SketchUp) and see what may be feasible.

55 minutes ago, Gina said:

Coming on nicely   I've been sneezing a lot and I don't usually suffer from hay fever but the pollen count is exceptionally high!

Thanks Gina. Actually, I suspect my hay-fever may actually be largely due to wood dust as I did a fair bit of sawing yesterday, and then brushing up the sawdust. Note to self - must get a mask!

5 minutes ago, JamesF said:

 

I'm going to have a little play with the measurements now and see if I can arrange the joists to avoid cutting any of them to go around the piers.  Or at least to minimise the number that have to be cut.

James

Looks good James.

It may also be worth thinking about placing the joists and noggins to minimise the need to do too much cutting of whichever floor sheets you choose to use. My floor joists are positioned so that standard ply panels should (I say should!) have joists supporting all edges. Time will tell if I got this right or not ?

Only a short update today. I'm struggling with hay-fever so haven't done much other than put in a few screws. Here're a few pics from yesterday and this evening showing the addition of the blocks half way along the roof span which will support the apex beam (or ridge beam as I believe it should be called), and the South beam now fixed in position. I'm a little unhappy with the South beam fixings - the beam can still twist slightly away from the vertical. I'm hoping this will stiffen when the roof rafters are fitted, but I must ponder on this before deciding whether to change the way I've designed this. By the way, the bracket clearly sticks out above the top of the beam. This won't be a problem once the rafters go on!

I've also been thinking about how to keep the frame square. Right-angle brackets are insufficient on their own to keep the frame square. Adding diagonal bracing is difficult as the obvious place to put these would prevent the roof from rolling open! The roof OSB sheets once fitted should ensure everything is held together well, preventing risk of twisting, but I'd rather not have to have the roof integrity rely on the OSB alone; it would be good to have the frame rigid on its own before the OSB is fitted, if possible.

If anyone has any thoughts on this, please let me know! Thanks

Once again didn't get as much done as I'd hoped. 

Working on the roof seems to involve endless moving and climbing up step ladders for the smallest task, which is surprisingly time consuming. 

I dismantled the roof frame and took down the wheel beams, as I realised it would be better to screw the blocks (that will support the apex beam) to the wheel beams from below. This took a while but they're now back on the roof!

Also cut the joints in the south end beam to attach it to the wheel beams, involving loads more trips up the step ladder with the heavy beam to check the fit, back down to the work mate to take off more wood, back up to check the fit, and so it continued. Feel like I've had a work out ?

Will post pictures tomorrow. 

Looking good James ??

Meanwhile, back on the observatory build.... ?

Have a free day today, but just realised the England game is on this afternoon and not this evening as I thought. I best crack on while I can!

Great progress James. And good idea to label the rods/blocks. There will almost certainly be minor variations and trying to figure out which goes where without labelling beforehand could be a real headache. I label stuff also - you can see some of my labelling on the wheel beams before they were lifted onto the roof to indicate which is which and orientation, and also numbered the wheels/holes they were matched to ? 

12 minutes ago, JamesF said:

I wish

Mistakes are however part of a learning process, not something to be regretted.

James

Absolutely!

Another day that turned out with only limited time on the observatory build. And there was me thinking I'd have the whole day to myself ? . Well, the non-build time was to visit family, and to play taxi for my daughter who can't drive yet while her ankle heals, so I guess I shouldn't get too selfish - it's nice to help others ? .

So the time I did have was spent finishing off laying the V track. Bit fiddly getting the short extension pieces adequately lined up with the longer lengths already partly fixed but eventually got them in a position where I was reasonably happy and inserted all coach screws to all four sections. A very small lip on the join between sections needed a bit of filing, but the wheels now cross the join with hardly a hiccup.

One thing I've noticed now that I can roll the roof frame along the entire length of the obsy is that the south-eastern wheel lifts slightly part way along the track. After much rolling, pondering and head-scratching I've decided to leave it as it is. With 6 wheels I think it's impossible to get all 6 to be in full contact at all times. The reality is that at any one time there's likely to be only 3-4 wheels in good contact with the track. Once the rest of the roof is built there will be a lot more weight which may improve contact as the wood bends slightly under the weight. So, I'll keep eye on this. As it is, the frame rolls really easily along the whole length; in fact I can roll the frame with my little finger. I'm sure it won't be this easy once it's fully loaded but this is a good sign.

Before packing up I cut out the EPDM over the warm room ventilation holes in case I forgot later on, and temporarily fitted the soffit vents to hopefully stop creepies setting up home in my nice dark and warm roof space ? .

No time to start cutting the north and south beams to replace the temporary ones currently serving to hold the frame together. A job for tomorrow....

Great stuff, another build to follow ? . Good luck Alex. It's pleasing to hear that myself and James have been able to inspire you to take the plunge! One advantage of us being a little ahead of you is that you can hopefully learn from our mistakes (well mine anyway - I'm sure James won't be making many of those ?).

I concur with James' point above. My build followed similar lines in that the outer floor joists are a few centimetres wider than the wall studding which gives an edge to support the flooring. I poured over my SketchUp design for more hours than I can remember during the design stage and tried to visualise actually building the thing - where I would add bracing, attach brackets, insert screws etc etc. I found this really helped identify problems and solutions before I went anywhere near real timber.

I'll be following your build with great interest. Post loads of pics!

Kev

1 hour ago, JamesF said:

I'm quite looking forward to this bit being finished as after that there's a lot of timber work that can be done piecemeal, so I can make progress in any spare 15 minutes or so.

James

Yeah, it was a great feeling when I'd finished the concrete work. Too much like hard work! Much more at home with cutting up bits of wood ? 

42 minutes ago, JamesF said:

Oh, and whilst I remember... Wickes.  They used to be great.  I always preferred to go there before any of the other local DIY sheds.  At some point recently however, our local one has become utterly useless.  It's now got to the point where I'll try all the others first.  It feels like they've just become a kitchen and bathroom showroom now

James

Agree there. Quality of their timber can be horrendous. I was after 3m lengths. Some of it was so twisted it would hardly fit in the rack. Ended up in Jewson and picked up 3.6m lengths that were pretty much dead straight.

Thanks guys - dry track it is!

Well, after spending half the day trying to find the size timber that I needed, I eventually managed to actually do some building. Wickes was hopeless for the longer lengths I wanted for the apex and north and south cross beams, so had to do some driving around. Eventually found what I needed but didn't get home until early afternoon, and then with lunch etc etc, where did the day go?

Today's update - I made a "jig" to help me ensure the two tracks would be parallel. Unsurprisingly, it took longer to design and make the jig than it did to align the tracks and screw them down. For the moment I've only put one screw in each end, just in case I need to adjust. The acid test is to make the outer frame of the roof and actually check that it runs square. Once the track was fixed, the wheel beams were put on the track and joined with temporary cross beams. One end was screwed to the wheel beam, the other was just clamped to the beam to allow me to adjust if necessary. Few images below of the alignment jig at the south end of the track, and at the northernmost point above the warm room. It was then I realised that I needed to cut and add the extra metre of track needed to complete the entire track, so I could check the wheel alignment along the entire distance it will need to move. D'oh.  I packed up before screwing the extra track extension, so this is where I'll pick-up tomorrow.

I have to say though - the roof frame moves so sweetly with the slightest touch - it's completely satisfying! Even my son was impressed! Hoping to make more progress tomorrow.

14 minutes ago, RayD said:

Ha ha just a few to go then, Kev.

Looking really good, Sir!

Indeed! Thanks. 

My friendly plumbers been and gone.

Time for some observatory action ? . What could possibly go wrong ?

27 minutes ago, RayD said:

Dry, Kev.

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 ? 

2 minutes ago, JamesF said:

 Sufficiently scary to know that I really don't need to own one though ?

James

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!

2 minutes ago, JamesF said:

Here's one you wouldn't want your fingers anywhere near:

 

James

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

4 minutes ago, JamesF said:

What you really need for cutting the holes of course is not a router, but a chain mortiser.  Imagine a vertically-mounted mini chainsaw combined with the mechanism of a pillar drill.  A very cool (and wickedly dangerous) bit of kit.

James

?. 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.