New Observatory preps and build

[jnb]

Quite pleased with todays slog. Completed the west wall frame, installed the linings on 3 walls, insulation and vapour barrier to the west wall and then added shiplap to the west wall. Light drizzle at times today but not enough to worry about (not even enough to stop for a coffee )

Insulation _and_ vapour barrier? I thought that that style of foil backed sheet insulation was meant to have an inbuilt vapour barrier? I ask because I'm half way through building a studio for my wife and had assumed I wouldn't need a separate vapour barrier.

[fwm891]

Insulation _and_ vapour barrier? I thought that that style of foil backed sheet insulation was meant to have an inbuilt vapour barrier? I ask because I'm half way through building a studio for my wife and had assumed I wouldn't need a separate vapour barrier.

The foil is more for for heat regulation. This extract is from the Celotex website: Celotex cannot be used as a cavity barrier alone but it can pass by a cavity barrier. In other words, the cavity barrier needs to be between the Celotex and the outside leaf.

[Gina]

Cold and windy but dry and sunny today so more progress may be possible

I may be able to sort out my motorised roof opening/closing system today I need the roof open to see where the rope and pulley are going but the rain lately has prevented it . Once I start this I'll start a new thread on it

[Laowei Tony]

I'm a little concerned about the use of a vapour barrier. A vapour barrier is put on the warm side of a wall (inside) to prevent moisture from migrating through the insulation and condensing when it meets the colder outer surface. A vapour barrier of polythene or similar non- breathable fabric beneath an outer wood cladding is inviting rot to occur.

I would recommend using a fabric material on the outside walls like Tyvek that allows moisture to escape, not to be trapped within walls.

Luckily as these constructions are not air tight moisture shouldn't be a problem. In a warm room though it could be, depending on the number of air changes in the enclosed space per hour and the humidity produced.

[fwm891]

Sat: More progress today around the build:

More work on the comp bay and the rials to take the tracks for the RoR wheels is now in place.

I've also started modifying the wheels by removing the thrust races so I can set then into the timber framing of the RoR itself.

Drawing mods for the roof have been finished so I can now start setting out the shapes on the plywood before cutting.

Some photos from some of todays exploits....

Wheel mod was awkward - had to first make cuts with a junior hacksaw through the centre hole (3) to break-out the centre hub. Two cuts were at about 90° to each other. The third between them on the opposite side. Then a little persuasion to first take the small section out making room for the other two (hammer and an old 10 mm bolt worked wonders for this )

[Gina]

Couldn't you find any fixed castors then Francis?

[fwm891]

Hi Gina, Yes lots of fixed castors around but the size of the normally square base plate was too wide for the size of wheel I wanted. The option of buying just the wheel with the swivel and single bolt hole meant I could keep sizes down and make sealing around the RoR easier later.

Adds about 30 mm a side to have the fixed base plate.

[Gina]

Ah - I see

[opticalpath]

Hi Francis. I'm just catching up on your observatory build. It's looking great and has gone up amazingly quickly ..... despite the weather ... impressive!

All that weatherproofing and insulation (not to mention proper foundations) puts my old shed to shame!

Adrian

[fwm891]

Hi Adrian,

Its coming along. The few dry days made all the difference last week. Able to knock-up all the wall frames and get them covered inside and out.

Day off today as the forecast was rain anyway. I could do with a couple more days of dry weather so I can layout the roof parts. A few more castors to dismantle if it stay wet.

I can at least rough out the roof timbers and ply panels in preparation, that will save some time if I have to juggle with weather windows.

Just ordered an SX Loadstar guider from FLO

[fwm891]

Weds: Working on the RoR parts in the garage today. Too windy to chance handling them outside but managed to get both the side panels cut to shape and am now starting on the timber framework. Where possible I will leave timbers attached to the plywood sides but most will be simply given a temporary fix to position them, then unfixed until I can get parts onto the obsy building.

All just seems painfully slow at the moment (or I'm being impatient!)

[fwm891]

Thurs: Nothing much done today. I did however try one of the RoR side panels on the main build between storms.

Photo 1 shows the panel in its closed position. Phot 2 shows it fully open. The cut out in photo 2 has been done in PS and is an approximation of the actual cut out in the side panel.

Guess the weathers down to me as I've just received my Loadstar from FLO and plugged it in so not expecting to use it for a while

Next thing is to get plenty of waterproofing on the side panels and the roof timbers before I try to assemble things - that will all need to be done in-situ.

Photo 1

Photo 2

[Gina]

Nice progress

[opticalpath]

Moving along nicely, Francis, despite the weather.

Adrian

[fwm891]

Thanks Adrian / Gina.

Been 'asked' to do a few 'other' jobs today - or no diner!!

So limited myself to a practice wheel housing / cutout before starting on fitting wheels to the support timbers.

This is just the housing cut with 35 and 30 mm forstner bits with the smaller being squared off with a chisel. 35 mm bit depth 15 mm, 30 mm bit 13 mm deep.

A 30 mm repair washer drops into the wheel bracket and will be fixed via a bolt going through the timber.

[yesyes]

I would have skipped the dinner... small price to pay...

[fwm891]

Sat: Managed to fit the 8 castors into their respective housings and fit them to the side panels. Still 2 more castors to fit although these are more guides than weight bearing. Tried the side panels on the building again and the wheels run really easily along the side of the obsy so quite pleased with that. The remaining roof frame and the ali skin won't add a great deal of weight to the roof so things should move OK.

Took some more measurements while the side panels were on the obsy to make sure I get the tolerances right for the roof frame. So that is the next part of the project. According to the MO forecast next Monday and Tuesday are supposed to be better days so I'm going to try to get the roof frames made before then and hopefully fit them Mon/Tues.

[fwm891]

Sunday: Basic roof frame now complete. Rain right on cue, everything too wet now to try and get the frame in place today....

Front drop-down frame still to make but I'm leaving that until the side panels and main frame are in position so I can measure directly across the opening.

Photos will follow once the frame and side panels are in-place and before the ali sheeting goes on. Note to self - fit the stop blocks!!!

[fwm891]

OK Monday: Roof frame fixed to side panels and everything (i mean everything) coated in more preservative. Too dark when I finished tonight for photos, will try and do those tomorrow along with making the drop down top section to the south wall.

May just extend the west wall track support a little at some stage. Most of the time I won't need to fully open the roof even to view around the zenith and when looking low to the south I may not need to do more than drop the top section of the south wall, which is why I'm unsure about extending the track support. I could do what I did with the last obsy and use a clip-on extension rail. That way it wont obstruct the door 90% of the time. When I need to view around the pole I can put the track extension in place to fully support the roof when rolled right back.

The east wall has a full length track and I hoped that it would offer enough support but running the roof back-n-forth today I could see the roof sag a little as one of the wheels came off the end of the west wall track when the roof was fully opened.

Easier to deal with now than when the ali is in place and things are difficult to access. TBC...

Possible track extension...

[Gina]

Coming on nicely Francis

[fwm891]

Thanks Gina,

Photo from a higher level before I get going this morning on other bits...

[fwm891]

Covered over with a tarp at the moment as the weather has gone down hill and I really want to get the interior a lot drier s I can try and lay some sort of flooring - good water barrier definitely required.

[opticalpath]

Shaping up nicely, Francis. Hope the forecast is right and you get a a day or two window before the next rain arrives!

Adrian

[fwm891]

Thanks Adrian,

Waiting for the ali at the moment so I can get the structure water tight and the mount and scope in place. Going to run temp power and data cables above ground for this winter and hope that the weather next year is kinder so I can lay them properly.

Francis

[Gina]

Amen about the weather round here Francis Looks like your build is coming on very nicely I know the weather can be very frustrating - had that problem with mine

Good luck