When my bedroom was redesigned I decided I wanted to add a little personal touch with an LED lit Ceiling Island, Using Sketchup I experimented with many different shapes until I stumbled upon the Idea of using Ying Yang, I experimented with the size of the circle and then ordered 12mm MDF which had to be 5 by 10 foot boards so that the size of circle fitted, I then worked out the perimeter would be and ordered a 10m string of RGBW LED's from online-leds.com (https://online-leds.com/10m-rgbw-plug-and-play-waterproof-rf-controller-led-strip-lighting-kit-smd-5050.html) I cut out the Ying Yang from the MDF after some research I decided the best way to mount the LED's was at 90 degrees to the top of the MDF, so I used 3 thickness's of flexible plywood which I forced round the shape of the ying yang using blocks of soft wood which were screwed in place, the flexiply was then glued and clamped in place. I decided to cut a second ying yang to cover the underneath of the large piece. I attached the Ying yang to the ceiling using coach screws going into the rafters. I primed the MDF to stop the release of formaldehyde and coated in gloss white and matt black so that there was a contrast between the pieces, and the light was reflected as well as possible.
Step 1: Preperation
Decide upon how large the Ying Yang will be and order the correct size board (I used 12mm MDF), using the formulas for perimeters of a circle find the maximum distance of LED's required, Strips are normally sold in 5m lengths, if it is slightly over this don't worry as they will be set back about 6.5 cm all the way around, and it doesn't notice if there is a small gap at the end. I spent a long time looking for the correct set of LED's. The ones I went for are expensive and others can be found much cheaper, however from the reviews of these there appeared to be safety hazards with cheap ones, and the programmability of the more expensive ones is better. I ordered two boards and did one half on each board. Order the LED's and Flexible ply along with any other wood required that you don't have around.
Step 2: Cutting the Large Ying Yang and the Covering Pieces
Using a tape measure, measure at least the radius of the circle from both edges. Using a piece of string attached to a small nail positioned at the point found above, attach a pencil when the string is the length of the radius and draw as much of the circle as possible onto the board, keeping the string taught the whole time. Draw a line through the centre and two points on the edge of the circle, this forms a diameter, try to make this parallel to the long edge of the board. Measure the length of the diameter and divide by 4 and change the length of the string to this value and use 1/4 and 3/4 of the diameter as the centre for the two smaller circles. Using the same method as before draw the two other half circles, one going forwards the other going backwards (be careful not to make the large circle too small, I made mine with the radius 990 mm.) Draw around this shape 3 times and cut, you should end up with 4 Identical pieces. With two of them use a marking gauge to scribe 50mm into the board and re-cut, this creates the smaller covering pieces. On the edges that are facing downwards use a router to put a chamfer on the edge of the MDF, sandpaper would do but might take a while!
The process of creating the covering pieces may seem like a poor way of doing this, however it is the only way to do it that I have found, if you have other ideas please put it in the comments. If you decrease the radius to create a set of smaller ying yang, the curvature increases and they don't fit inside the larger ones ( Trust me I tried this!).
Step 3: Making the Supports for the Ying Yang
Using a circular saw cut the flexible plywood into 100mm (4") strips. This is the distance below the ceiling that the island will be. I advise using 3 layers of flexible plywood to give a solid upstand. Use a marking gauge to scribe 65mm in from the edge all the way round and 80mm in. The front face of the blocks to form the plywood will be placed on the back line. Cut a number of blocks that are 100mm high and use a plane to remove the corners on the outside edge, this is so that the contact area on the ply is reduced meaning that the bend will look smooth rather than blocky. Screw the blocks in place and glue the first layer of flexible ply in place, clamp and leave to dry. Towards the points of the ying yang, the ends of the plywood will meet, this should be done in the form of a mitre. Bend the next layer of plywood around the previous, glue and clamp. repeat this for the final layer, which should be level with the line that is 65mm in from the edge. I braced the ying and the yang by using two 4" x 1" timbers in the middle of the ying and the yang, these can also help provide extra fixing points.
(Sorry some of the pictures were taken after I had mounted the pieces)
Step 4: Attaching the Ying Yang
I cut some supports from tiling battons that were the distance from the floor to the MDF which were used to support the Ying Yang when positioning. I laid them out on the floor to get the positioning. I lifted the Ying into place and propped it using the supports I made earlier. this meant only two people were required to attach the Ying, rather two to hold it and one two drill and screw it into place, I used Coach Screws to attach the Ying to the ceiling, having found the rafters by knocking and making small holes with nails. I then used an impact driver with huge amounts of torque to bend the Ying to the ceiling as my ceiling is by no means level! I repeated this for the Yang. When the Ying Yang is attached screw the covering pieces into place lightly, do not countersink yet as this damages the integrity of the MDF and it wont hold the screws as well.
The image of the support and the level shows the amount of tension that was required to get the Ying anywhere close to level with the ceiling.
I cut a hole in the middle to allow the electrician easy access.
Step 5: Finishing the Ying Yang
I used an MDF primer to lock in the formaldehyde and to make it easier to paint. I filled the holes from the coach screws and then painted what was visible of the underside of the Ying Yang with matt black paint. I used white gloss paint on the uprights of the large pieces and the edges so that there was as much reflection as possible, I also used white gloss on the covering pieces. I used the black so that there was a clear difference between the two pieces. When all has been finished and LED's are installed, the holes for the screws in the covering pieces must be filled and then painted over. Leave plenty of time for this stage as you must allow each layer of paint to dry fully before repainting, the same applies for filling followed by rubbing back and painting. I advise doing as much painting as possible at ground level.
Step 6: Wiring
I used an electrician to wire in the LED's as it is going into the mains and I also had downward spots in the covering piece. On the set of 10m LED's I used the transformer is wired into the mains, so it was far safer to have this done professionally. The theory of the lighting is as follows, however I do not have a wiring schematic. Both strings of LED's are fed into one set of 5 cables, which was then fed into the radio controller, this was then wired into the transformer which was wired into the mains, this was in the loft space above the Ying Yangs, meaning that only the LED's are visible and very little of the wiring. There are simpler and smaller kits that are plugged into the mains and are simple to install, just secure the contacts into the correct terminals, plug in the transformer and Bobs your uncle. In this kind of configuration the black wire goes to V+, the white to W, the red to R, the blue to B and the green to G, these have to be connected correctly or the lights will not work properly.