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 Topic Title: downlights Topic Summary: In an oval shape - how ? Created On: 15 January 2013 10:57 PM Status: Post and Reply Linear : Threading : Single : Branch
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 15 January 2013 10:57 PM ady1 Posts: 807 Joined: 19 April 2005 Good evening A customer has an oblong shaped kitchen and would like me to arrange the downlights in an oval shape. Is there a mathematical solution to this, or any tips ? I have a laser, but not sure it will help ? Regards Ady ------------------------- Resistance is futile. 15 January 2013 11:16 PM Rulland Posts: 492 Joined: 11 April 2008 Two fixed points on the centre line and a loop of string wrapped around them- pencil in the loop and pulled outwards then moved around the fixed pins keeping the string taut, this will scribe an ellipse, may be worthwhile experimenting on the floor- distance between pins and length of loop will all influence the shape/size of the ellipse- obviously any joists will need to be accounted for!. Not simple-but looks good, done it a few times now, carefully measurement is the key to a good outcome. ------------------------- Those who make no mistakes do very little work!!...... 15 January 2013 11:21 PM rocknroll Posts: 9083 Joined: 03 October 2005 'The Gardeners Ellipse' use two screws, a bit of string and a piece of coloured chalk if a white ceiling. regards ------------------------- "Take nothing but a picture,leave nothing but footprints!"-------------------------"Oh! The drama of it all."-------------------------"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"------------------------- Edited: 15 January 2013 at 11:46 PM by rocknroll 16 January 2013 10:25 AM aligarjon Posts: 3291 Joined: 09 September 2005 i have laid them out on the floor as well, it gives a good idea of what you are trying to achieve. Then all you have to hope for is that the ceiling joists aren't in the way. Gary ------------------------- Specialised Subject. The Bleedin Obvious. John Cleese 16 January 2013 08:28 PM kirchoffs Posts: 191 Joined: 08 February 2010 you'd better not show your client the oval down lighters that are on the market. He's bound to like them. 16 January 2013 10:06 PM ady1 Posts: 807 Joined: 19 April 2005 Hey thanks guy's I had no idea that's how you do it. I'm much obliged to you all. Ady ------------------------- Resistance is futile. 16 January 2013 10:22 PM DOUGIE1000 Posts: 4243 Joined: 13 August 2005 Talk them out of it, had to wire a living room in a diagonal strips, nightmare, 2 of us spent about hours marking these 16 spot lights out in the living room so we didn't hit joists ------------------------- DougiePower Plus Electrical.co.ukMy mission is to live as long as possible......so far so good! 17 January 2013 10:43 PM ady1 Posts: 807 Joined: 19 April 2005 lol to be fair, the ceiling is getting repaired and replastered, its a bungalow and I can alter ceiling joists - otherwise, I would agree Ady ------------------------- Resistance is futile. 17 January 2013 11:09 PM sparkingchip Posts: 7704 Joined: 18 January 2003 Oval or segment of a curve? I think I would be trying to mark it out on the floor using three wooden lathes tacked together and two nails to slide them against with a third nail giving a temporary reference before it is removed. This is a traditional method for marking out boat hulls, useful for setting out bricklayers arch forms as you can make them the correct rise to work brick courses. Two nails at the end of the curve, the temporary one setting the depth of the curve, three lathes tacked together to form a triangle with the nails on the external intersection, pull out the centre one and hold a pencil in its place, then slide the assembly around the other two nails, it won't give a full oval though. Clear as mud! I can't find a diagram with Google. Andy 17 January 2013 11:19 PM sparkingchip Posts: 7704 Joined: 18 January 2003 Ellipitic Arch I can't find the three lath method of lofting on a Google search. Andy 19 January 2013 09:08 PM ady1 Posts: 807 Joined: 19 April 2005 Hmmmmm Fortunately - I'm quite 'arty' so would consider 'freehand' - but I've also just drawn on a piece of paper as follows. 12 dots in a 0 shape. top, bottom and sides on a cross axis and the others accordingly. Then 'it appears' that my spacings down could be 500, 1000, 1000, 1000, 1000, 500 and my spacings across could be 2000, 4000, 4400, 4000, 2000 so, i was wondering if there is a mathematical way like this of doing it. Maybe I could find a small shape to fit just above my torch and draw its enlarged shadow ??? The mind boggles Regards Ady ------------------------- Resistance is futile. 20 January 2013 09:19 PM M.Joshi Posts: 213 Joined: 10 January 2003 Originally posted by: ady1 lol to be fair, the ceiling is getting repaired and replastered, its a bungalow and I can alter ceiling joists - otherwise, I would agree Ady Incidentally, I bought a USB snake camera from Maplin in the New Year sale to see where existing joists are before drilling: Maplin snake camera The quality isn't brilliant, however it does come with integral LEDs for illumination and the brightness is adjustable. The camera is on the end of a flexible gooseneck which can be passed through an existing downlighter hole or a small pilot hole to survey. It could also be used for detecting pipe leaks in hard to reach places too. ------------------------- M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules! 20 January 2013 11:35 PM rocknroll Posts: 9083 Joined: 03 October 2005 Well you could always calculate the perimeter (P) of the ellipse and divide by the number of downlights you are fitting, the perimeter calculation is not perfect but if a (major axis) is not greater than three times the length of b (minor axis|) then it is accurate to around +- 3 to 4%. Look left for Axis; P ≈ 2 Pi √ (a² + b² / 2) For a ceiling use the 'Gardners Ellipse' method which involves tying each end of the string to two screw points, to make it easier drill a hole in the pencil about 1 inch from the point and pass the string through the hole. Regards ------------------------- "Take nothing but a picture,leave nothing but footprints!"-------------------------"Oh! The drama of it all."-------------------------"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"------------------------- Edited: 21 January 2013 at 03:53 PM by rocknroll 21 January 2013 10:00 AM rougediablo Posts: 112 Joined: 09 November 2011 21 January 2013 09:26 PM ady1 Posts: 807 Joined: 19 April 2005 Wow R&R !!!! That's a fabulous answer - and very kind of you to spend the time you have. I will enjoy working that one out - so will my dad (he's an accountant and loves number crunching !). Will let you know how i get on as i'm doing them over the next couple of weeks. Kind regards Ady ------------------------- Resistance is futile.
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