Hi folks. Interesting problem ... I am trying to come up with a structure which could be implemented using an aluminium extrusion technology or some similar light weight / strong / rigid material. My challenge is as follows: We are extending our house and creating a master bedroom with a vaulted ceiling and a trapezoid window, width 2.6 metres and height 0.95 metres min to 2.77 metres max. We clearly can't arrange a conventional curtain or blind for this non-rectangular shape. So we need to come up with a structure to support a heavy cotton blind that will cover this shape. Please see attached architect drawing of the window elevation. I am looking into making a folding screen out of four trapezoid panels made from aluminium extrusion with appropriate corner fixings and hinges. Given the weight of the fabric - approx. 3.6 Kg overall - I believe 20mm section extrusion should be capable of holding it? I have a rough parts list worked out - It's going to probably amount to about 25 metres plus of 20x20 extrusion plus about 16-20 hinges , eight 90 degree connectors and eight angled connectors. I'd be very grateful to hear any comments on this idea, and get an idea of where to get the materials? ( I tried to upload another scanned drawing of the proposed blind itself but do not seem to be able to. Will try in a second post...)
proposed blind construction.. (not sure if this works...) - hover over image tag, right-click, Open In New Tab maybe.. .
Yes, your links work. That's the good news... In theory - if you could prevent your frame from bending and collapsing under its own weight - it will work. But, I think it will bend and flex - it's a large frame, and will be very flexible and wobbly even before you add the fabric. 20mm box section ain't big at all. And this is ali - not the strongest. To prevent it from bending downwards under it's own weight is relatively easy to do in principle - you could add a thin, high-tensile cable as a tie going from the top hinged corner down to the diagonally-opposite one on each panel. They need to be none-stretchy... Having them behind the fabric would make them nigh-on invisible so shouldn't be a cosmetic issue. But I think you will find that the framework will still be flexing 'in and out' even if not 'up and down' - a bit like trying to hold up a sheet of paper by a side edge - it will wobble and try and fold over itself. To counter this you'd need to use a frame size that would prevent flexing along the X axis (I don't know if that's the right term - but I mean horizontally, since the ties will have cured the vertical issues...). So that would suggest a rectangular box section with the width of the frame being the widest part - does that make sense? Of course, you could always chust go bigger in both directions and forget the ties... Your corner brackets would need to be 100% secure too - all the bending/flexing forces will be focussed on these. So, in theory you can do this. But I suspect you haven't a chance with 20mm box-section ali. Do you really need to be able to uncover all of the window from its blinds? I mean a simpler solution would be to have a rail amounted along the top at a slope, with a couple of wee pulley wheels. The hanging fabric is then pulled up as with a normal blind, and should be left 'pillowed' at the top like a ship's sails...
Go for 25mm square box section, then find a metal fabricator to TIG weld the frame together. Why not use a stainless steel tension wire & have the sail with eyelets, would run along wire ok.
It shouldn't really matter how large a section he goes for (within limits...) as, once it's up, it's effectively 'weightless' and will be easy to move. Do you reckon even 25mm is large enough? It's nearly 3m long, held only at one end. Can you imagine the sinking feeling?
Thanks all for really interesting & helpful suggestions. I had thought that the ali 20mm box section 'Bosch Rexroth' type profile would be rigid enough to hold the weight of the fabric, but they are b.i.i.g panels and you're right 20mm is not big. I had wondered about additional cross braces, like in a sash window, which would be hidden by the fabric but even that might not be strong enough. I like the tensioner idea for strengthening, and also the MiG/TiG Welding idea too. I looked into the profiles and they come in many sizes from 20mm up through 30, 40 and bigger but I didn't want something too 'boxy'. I am now tempted to reconsider having the whole curtain (or 'sail' - nice way to look at it!) on eyelets on a tensioned steel cable. As long as I can think of a neat way to stow it at one end when the curtain's open.... Great ideas, thanks all!
Curtains (sail) tie back to clip on wall. http://moderninmn.blogspot.co.uk/2007/03/my-friend-wire-rope.html http://www.tecni-cable.co.uk/
The idea of using a tie instead of a strut is its size - a think wire in tension will do the same as a hefty strut in compression will do. I can understand you wishing to avoid a hefty box section, but in theory - using a strut to provide strength against 'sagging' - the main other strengthening required would be to prevent 'sideways' flexing, so the box section would only need to be wider rather than taller, say 50mm x 25mm. I know that's still big, but you'd mainly only see the 25mm profile when looking on to the panels. And with the fabric on the front, you could avoid seeing the framework pretty much completely. Anyhoo, it's also worth looking at other options like wot you are doing.
Trouble with a pull up blind is that the top edge is not a 90 degree square, it's angled into the roofline so the window is higher at one side than the other.
Should be able work out a system where you can have a cord attached to bind/sail which is running over a pully, so blind can be pulled up the supension wire.
Yep, definitely starting to think that way instead of the folding fire-screen idea. SImpler, cheaper, less to go wrong. Pull it up, hold with a simple tie, release and let gravity bring it back down.
Been thinking,what about Trapezoid Blinds, taken me ages to think of the name, sure you can still get them in the UK, years since I've seen one though. http://www.blindcornersandcurves.co...oid-blind-and-angled-blind-operation-diagrams Trapezoid blinds can either be vertical or venetian blind style, manual or electric. http://www.faberblinds.co.uk/product/internal-pleated-blinds
I knew I had seen some in new build I looked at Portishead or Portsmouth, but the name of the blind just eluded me for a while.
Ah, had seen those earlier on in the research and at an expo but my Interior Design Manager doesn't like the pleated look (and she's already bought the velvet material and parachute-silk lining )!
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