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Belly's Obsy Build

Drbelly

By Drbelly
in DIY Observatories

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Drbelly

Drbelly

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Small update

Despite having to look after my 5 year old daughter on Monday who unfortunately developed D&V and dodging the showers we had yesterday I've managed to get the floor frame down and most of the joists in and noggined. I miscalculated the number of joist hangers so need to pop to Wickes this morning to buy another couple then hopefully will get the 18mm ply down.

IMG_0554.jpg

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Drbelly

Drbelly

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It's looking good so far but...

Are the outside timber meant to be laying down?

I decided to lay the outer frame 6x2's flat on the blocks instead of vertically as this seemed to me to be more stable. The joists are then suspended of this frame using hangers.

Have just got the last joist in and it's seems very strong and doesn't move at all when walking over it.

Now to crack on with battening the joists for insulation under the warm room floor.

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malc-c

malc-c

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Are the outside timber meant to be laying down?

That shouldn't be a problem. I used the same method, however I had support of a brick wall all the way along the length of the timber. Whilst its probably sound I would of made a frame around the inside as there could be a slim chance of flexing having the coping board suspended between blocks.

post-10726-0-50987400-1345654058_thumb.j

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Drbelly

Drbelly

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That shouldn't be a problem. I used the same method, however I had support of a brick wall all the way along the length of the timber. Whilst its probably sound I would of made a frame around the inside as there could be a slim chance of flexing having the coping board suspended between blocks.

The maximum span between blocks along the long axis of the structure is 75cm. I've had a good walk/jump about on it and can't see any flexure - it seems rock solid. However there is still the added weight of the walls/roof to think about. One option may be to add wooden bracing off the floor in the centre of the spans around the frame if needed - I'll have to keep an eye on things.

I have managed to get the remaining joists/noggins done and have battened and insulated the warm room floor.

IMG_0555.jpg

The next step is to get the cable ducting sorted and screw down the ply after giving it a coat of preservative. One question I have though - should I leave a gap around the perimeter when laying the ply so that the stud work walls screw down onto the 6x2's or should I build the studwork off the ply :icon_scratch:

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malc-c

malc-c

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Chris,

I screwed the stud work on top of the flooring, rather than but the flooring up to the framework. The only advantage of putting the flooring down after the frames is that it's easy to replace the flooring in the future, but given the amount of preserve you put on, and the fact that you have good air circulation between the blocks I would predict it would be a few years, possibly decades before that would happen. For me, placing the studding on top of the floor, which sat ontop of the wood capping gave a good solid fixing for both walls and floor.

Each to their own really

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Gina

Gina

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I think if you put the flooring inside you'd have a problem with a possible gap between floor and wall (unless you clad the walls). I hace plywood cladding in my warm room but not in the scope room.

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Drbelly

Drbelly

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I managed to get phase 2 completed before rain stopped play this afternoon. All the ply is screwed down and I have installed 2 ducts under the suspended floor with pull-throughs ready for power and data cables.

IMG_0559.jpg

One thing I have learned today is to make sure that my tarp is correctly positioned over the build. This morning when I went to unwrap things I discoved a pool of water on 2 of the 4 ply boards because water had collected on slack areas of the tarp and had come through overnight. The water was quickly mopped off and some welcome breezy sunny spells has dried it nicely and thanks to the preservatve I can't now tell where the water was so hopefully it hasn't soaked into the ply and affected it. I have made sure that the tarp is pulled tight today so that all rainwater runs off it instead of being allowed to collect on the flat floor structure.

It was fairly tricky getting the ply down and cut out arounf the pier and cable tubes but I'm happy with the result and can move on to phase 3 - the superstructure.

IMG_0560.jpg

I was hoping to get my mount and telescope out onto the floor to work out how high I can take the walls and whether I need to consider a drop-down flap but the weather intervened so this will have to wait til next time :rolleyes:

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Drbelly

Drbelly

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Really coming along...I opted for a drop down wall on one side that was facing south (ish). It all depends on the orientation of your plot, and how good your skies are low down to the horizon.

The long axis of mine runs almost exactly north-south with south being towards the chicken pen on the photos.

I managed to get the scope out this morning to take a look and see how high I can take the pier and walls. If I plan to have the side walls along the long axis 2 metres tall I could have the top of the pier including mount plate at 145cm and I would still be able to park the scope sideways horizontally with the top of the OTA being around 185-190cm. This would allow me to open and close the roof without knocking the equipment.

I have good views to the east and south so would like to be able to get as low as possible in these directions and so may need to consider a fold down flap on 1 or both of the southern gable and the eastern long axis walls. I'm not sure if having a flap on both south and east walls would be feasable as it may affect the stability of the structure too much. Hmm .... lots to think about and mull over. :icon_scratch:

Whilst I was pondering dark clouds were quickly gathering and rumbles of thunder were sounding. I just managed to get the scope and mount back indoors and the tarp on before the heavens opened and it absolutely chucked it down :clouds2:

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Gina

Gina

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I had the same problem with my obsy. I agree, two fold down walls are really on. I opted to add the top quarter (or thereabouts) of one wall to the roll off section and have the top part of the end wall folding down. The roll off section is heavier than just a roof but with 4" diameter wheels does move quite easily.

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Drbelly

Drbelly

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Managed to get a couple of panels made this afternoon. I've decided to make the walls 1.9m high. Once one of the panels had been made I got the scope back up onto the obsy floor and checked the field of view with the top of the tripod at 135cm instead of 145cm as I've brought the walls down by 10cm. At this height I should be able to see down to roof-top height along the eastern horizon but have decided I will need a drop-down flap on the southern wall to get as low down as posible. The panels need to have some bracing added before they can be screwed down. I need to decide where to have the door before I make up more panels - I'm not sure wether to have it on the gable-end wall or to the right of the long wall nearest the camera on the photo below. This will affect how I position the slope of my warm room roof :icon_scratch:

IMG_0561.jpg

The forcast is for lots of rain tomorrow so the tarp is back on and secured waiting for the next clear day when I can continue. If I get time I may build some of the panels in my outbuilding where the studwork is being stored so that I can then crack on with the roof. I'm going to start looking at getting the rollers and u-channel sourced and also the roofing materials. I think I have decided on using OSB sheets for the roof covered with the glued-on rubber sheeting that I have seen others use. Any recommendations on where to source these various items would be handy :icon_question::smiley:

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malc-c

malc-c

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I still have a couple of bookmarks, but not sure which company I used

Ali channel http://www.metals4u.co.uk/Aluminium-Channel/1.14-x-34-x-18/14/822/detail.asp - they supply 5m lengths of U channel from around £10 per length depending on the width and thickness. For example 32mm (w) x 13mm (h) from 3mm thick ali - £9.90 +Vat and delivery

Another http://www.metals4u.co.uk/Aluminium-Channel/1.14-x-34-x-18/14/822/detail.asp but they seem more expensive at around £22 for the same item

Rollers were from Screwfix http://www.screwfix.com/p/rubber-tyres-fixed-50mm-pack-of-4/94751

Hope that helps

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Drbelly

Drbelly

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Malcolm, thanks very much for the links. I've read differing opinions regarding rubber vs nylon wheels and wasn't sure which to go for. Some people believe that rubber tyres may eventually deform causing a flat surface on the part of the tyre in contact with the runner when the roof is in the closed position. Have you found any evidence to support this with your rollers?

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Drbelly

Drbelly

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Can't say I've noticed any problems a year on from fitting them

Malcolm,

I picked up a set of the 50mm rubber tyred rollers from screwfix yesterday. I'm looking at using 1" x 1/2" x1/8th" ali u-channel for the roof to roll on. Having measured the wheels I have noticed that the distance from the edge of the tyre to the fixed metal circular section on the wheel is just under 1/2". The width of the wheel including this metal bit is around 3/4". I have some concerns that this fixed circular part will catch on the rails although the rails are wider. I remember from your thread that you had some problems with binding on the rails and had to remove 1 of yours - was it because of this issue? If so I may opt for the 75mm tyres from screwfix.

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malc-c

malc-c

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Hi,

The reason I used just one rail was two fold. 1st as I had a drop down section which used standard hinges there was an alignment issue which could cause the wheels to derail. 2nd, given the tollorances, it's difficult to get both rails 100% parallel and to get all 10 wheels perfectly lined up and square to each other so that they track without binding in the tracks. You could get over this by using wider track, but for me this could lead to the roof having a latteral movement. I found having one track was the best compromise. You may find tthat when you fit the wheels in the tracks there is enough clearance as the dimensions are external, so you'll have the thickness of the material giving the clerance required

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