Fold-up frame screen, disguised as ceiling lamp, motorized masking - AVS Forum
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post #1 of 11 Old 08-02-2012, 01:38 PM - Thread Starter
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Hi everybody,

I've mostly been a more or less passive but avid reader of this great forum, but now I feel like contributing myself by presenting you my ambitious screen building project and hopefully spurn some discussion or encourage others to engage in something similar.

I'm German so please forgive my sometimes clumsy English or unusual vocabulary.
And grab a coffee if you're interested, as it's gonna be quite a long read =)

How did it all start?
Well, I've been used to watching my movies on a 40inch Sharp LCD TV and of course there always seemed to be something missing. Soundwise I've build up quite a set of nice speakers, sporting the Canton Vento series up front, Monitor Audio RXFX for rear effects and a nice little SVS sub for the deeper end ...
But visually I've been missing the "wow" of enjoying a crisp Blu-Ray on the big screen so I decided on upgrading to a projector/screen combo. But alas, money IS of object to me, so I was up for compromises:
I don't have a home cinema optimized living room, aka "bat cave", meaning I can get quite dark but there will always be residual light and scatter from my light colored walls and ceiling.

So I decided it should be a low-gain grey screen, especially as my image width is only gonna be around 75 inches.
Being limited by width I thought of getting a 16:9 screen and still planning to use my TV for casual and low quality viewing, I thought a motorized screen would be best.
Now I also thought a tension screen would be nice to stay level for years and I'd also prefer some automized masking for the various screen formats I'd like to use.
Unfortunately screens with those options combined are very rare and very expensive around here, so I almost resigned to making various compromises ... until I stumbled upon a guy who made his frame screen fold up to the ceiling and setting it up with LED stripes to double as a lamp when not used. This seemed like a great idea and it developed into a DIY project I'm going to tackle in the next few weeks.

The plan:
I'm going to build a grey, low-gain frame screen from scratch with a nice masking frame around it. It will be fixed to the ceiling by hinges on the top hand and strong (hidden) magnets on the folding, bottom edge (for optical reasons of course). Also, there will be a masking roller blind on the top, driven by a stepper motor, allowing me to mask every aspect ratio I'll come across.
Given the small dimensions of the screen, my standard room height even allows me for 4:3 ratio movies, leaving still enough room under the lower screen edge for the center speaker and low board.
In its retracted position on the ceiling, the back of the screen will use a milky acrylic glass plate as the lamp cover and LED stripes behind it for illumination.
A two-phase power connection on the ceiling allows me to use one for the lamp and the second for driving the motor.

Upcoming problems:
My biggest concern will be the damping while lowering the screen. I thought of using damped gas springs similar to those used to open car hatches, but those are usually too strong and as they support the opening movement they might make it even harder for me to move the screen up to the ceiling, especially considering the weight which will probably end up around 60-80 pounds.
there are inverted pull springs supporting the closing movement, but those might prevent the screen from staying perfectly straight in its opened position. So I'm basically searching for pure dampers. Additionally they will naturally have to be on the inside of the folding frame, so in the closed position I will have to hide them "inside" the frame to fit it perfectly close to the ceiling.
Other problems might arise in fixing the screen to the ceiling, balancing the weight, making it look perfect from the back (lamp) side, controlling the motor etc. etc. by now I don't know what I thought it starting this =)

Parts so far:
I bought a high quality 0.61 gain grey screen to fit on a roughly 80 by 60 inch sturdy stretcher frame. I got myself a 7 meter LED stripe to pace on the inside of said stretcher frame. Also magnets (everybody loves magnets =), with about 30 pounds of holding force each. Adhesive masking. The biggest black IKEA tupplur roller blind for the motorized masking. Modular TinkerForge electronics to drive the motor and adjust the masking positions, also a suitable stepper motor of course...

Parts to still get:
Suitable wood for the outer frame. It will overlap the stretcher frame of course but has to leave room in between for the roller blind masking. I also don't want to fix the actual screen frame to the ceiling because I worry it might warp, especially in the horizontal position on the ceiling. Also I wouldn't want to fix the quite heavy acrylic glass to the screen frame but rather to a more sturdy outer construction.
A lot of other small things still have to be got for fixing the two frames to each other. Maybe some more tools for cut-outs in the frame and to make everything look really good and professional.

But words are wind and you guys probably can't quite imagine my constuction without pictures. And there will be a lot of pictures, accompanying the whole project and - providing everything works out as intended - a video of the screen in action.

Projector-wise I'm still quite undecided between the following, but that decision will be made at the end of September after my upcoming vacation in Mexico:
- Epson TW9000 (6010 in the US I think)
- JVC X30 (RS45?)
- Mitsubishi HC9000

Each has its strenghts and weaknesses, I know, but I doubt the differences are too big. If any of you have experience with those projectors and a very grey/low-gain screen, advice is always appreciated. I especially doubt if the difference in black is still big considering that kind of screen...
I'm of course also open to any advice, criticism or other comments on the project itself!

Well, stick with me if you're interested, updates will follow on the weekend once I bought the rest of the stuff I'll need and hopefully started building the outer frame...

EDIT:
Completely forgot about telling the projected cost of the whole thing:
I always hesitated in spending more than a three figure amount for a screen, so that's what mainly kept me from buying a high-quality multi-format motorized screen and drove me to DIY in the first place. Initially I wanted to keep it close to the 500€ mark (about 600$ right now), but due to the motorized masking and the double function as a lamp the whole thing will probably end up between 700 and 800€ (850-970$), which is still fine with me considering the great quality screen and overall construction. Besides, the tinkering and experimenting are priceless anyway, especially if everything works out as intended...
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post #2 of 11 Old 08-08-2012, 02:42 PM - Thread Starter
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So it took me little longer to reply, mainly because I've been quite busy, but here we go:

Everything started by buying a lot of stuff of course:



For the outer Frame I decide to use two layers of 16mm (.63 in) medium density fiberboard (MDF). Two layers because the front layer will overlap the actual screen in parts, as you'll see later.
So I got the following pieces cut precisely in the hardware store:
- 2x 220x15cm (86.6x5.9 in) for the upper and lower part of the back layer
- 1x 190x18cm (74.8x7.1 in) for the top part of the front layer
- 1x 190x15cm (74.8x5.9 in) for the bottom part of the front layer
- 2x 145x9cm (57.1x3.5 in) for the side parts of the back layer
- 2x 175x15cm (68.9x5.9 in) for the side parts of the front layer

This will give me an actual image width of 74.8 in. I can go no bigger because my wall is just 149 in wide and I still have to fit the front speakers.
But as I'm limited by the width I wanted to make the best of the height and decided on a 1.33:1 ratio and using the motorized masking roller blind to change to every possible ratio.

I already got a the stretcher frame and the screen itself. I decided to also fix the screen to the other frame by small hinges to be able to remove it easily if I might want to change it some day or stretch it some more.
A major design change came up while shopping for parts:
I had a hard time finding an acrylic glass plate of a suitable size and the ones I found were either too thin to be stiff enough or too heavy to feel comfortable...
So I decided to switch to very light decorative wood frame with Japanese Shoji paper for the lamp cover which wil be much ligher and will also give me nice, diffuse lighting.

Then of curse there were a lot of small parts to get as you see in the image above like hinges, screws, brackets etc. also black paint, damping material (kind of a foam used for insulating windows and such) and other parts I will come to later.

Building the outer frame:

So I started by cutting out holes for the magnets that will keep the swinging (lower) part of the screen on the ceiling while it's not used. I only do this on the side parts of the front layer and will fix the magnets to the low bar of the back layer though the holes.



I also got myself a router(?) to cut the corners of the MDF to 45° angles so it will look good later on after it's been coated in black velours. It's a very nice tool to work with and I will be using it a lot as you'll see by the cut-out parts int he wood later.



Next I started to fix the "stripes" of MDF to each other to build the frame. In the lower corners a used four screws as seen in the next image. No screw in the middle as that's where the magnet will be fixed from the other side! As you can see the side parts of the back layer are retracted from the visible screen width to allow for the masking roller blind to run down between the actual screen and the front layer of the frame.
I fixed the other corners int he same way using more screws on the upper corners as the have to carry a lot more weight.



I also cut out the front layer to allow for the door hinges and easily removing the whole frame from the ceiling if needed. Using the router I also lowered the part where the hinges are fixed into the MDF so the frame is perfectly aligning with the ceiling when moved up.



Preparing the motor and roller blind:

I opened the brackets used for fixing the roller blind to expose the spring and remove it (as it would just make it harder for the motor to rotate the blind). I also removed the plastic chain as it won't be needed:



Then I proceeded to cut an aluminium bracket to fix the motor on. After drilling the holes for the motor housing and the shaft, I fixed the motor to the bracket and the rotating part of the Tupplur blind to the shaft:



The Tinkerforge stepper motor driver is simply screwed to the back layer of the frame on the right side. I connected a USB cable to it leading to the lower-most part of the visible screen just behind the front layer. This allows me to connect to the motor driver and change it's software etc while keeping the connection invisible except from very flat angles.
I also connected a so-called "joystick bricklet" (from TinkerForge) to the driver to allow for manual control of the roller blind. It drilled a whole to fix the joystick inside the frame from the back but still make it accesible on the front. As everything is black-coloured it shouldn't be disturbing the visual appearance or movie experience.



So that's how the outer frame looked in my living room after those first steps:



Then I proceeded to fix the motor's bracket to the frame and connect it to the driver:



I also started to fix squared timber(?) to the frame which will be used in two ways. On the one hand it will be used to fix the stretcher frame by said hinges to it. On the other hand it will be used to fix the lamp cover to it with a little spacing to allow the LED stripes to create a diffuse lighting. As it's naturally hard to describe I created a quick drawing:



Woud is represented in brounish colors, hinges/screws in black, the japanese paper cover in blue, the damping foam in grey, the LEDs in red.
The black velour covering the frame will go from the frame's edge diagonal to the squared timber.
If you think of it inverted on the ceiling it will look like a flat black pyramid that has been cut off and topped by the lamp cover. i try to illustrate this some more by a white paper that shall represent the planned wrapping of the frame in black velours:



After fixing the other squared timber parts there was just the roller blind to fit in there. On the next image you can also see the motor's power supply:



So by now the outer frame is almost finished. Here's an overview image of the current situation:



Next I plan to fix the other part of the hinges to the ceiling and hang the frame for a quick test. The whole thing has gotten quite heavy by now, mainly because of the MDF (about 50 pounds), so I might have to increase my weight estimation. Good thing I decided against the acrylic glass or I wouldn't know how to lift the whole thing up to the ceiling eek.gif

I will also start wrapping everything in the black velours and build the stretcher frame as well as fixing the screen and the LED stripe to it. The main problem still remains the damping while lowering the whole contraction from the ceiling and keeping it perfectly rectangular in movie mode while not making it too hard to close the whole thing manually back to the ceiling... I also worry a little about the magnets as they are only fixed by one screw each, so I thought of using one or two more just to feel safe.

As I'm busy the next few days I might only be able to continue next week, but feel free to ask question, provide advice, citicize me etc.
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post #3 of 11 Old 08-08-2012, 07:32 PM
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I have a criticism.

Where has such a meticulous, motivated DIY'er been spending his time? Building Yachts? Engineering Dams?

Sheesh....your setting the DIY Bar pretty high with this project! tongue.gif

If you haven't already got a Pj, considering the lower gain of the type screen your considering I would strongly urge you to consider the 6010 above all others.

It's the brightest on both Normal and Low Lamp settings.
It will really take advantage of it's 200K:1 On-Off Contrast by servicing a Gray Screen
It comes with an Extra Lamp & most excellent Chief Mount
It comes with a Free Replacement of the Original Lamp if it expires before the "3 Years " Warranty expires.
It comes backed by what is pretty much acclaimed by everyone as the best customer Service Dept ever. They are not perfect...but damnable close!

The Mits isn't in the running (IMO) and the JVC just continues to exhibit too many issues, besides being grossly outgunned by the Epson.

One last item.

your Project looks to be far too classy to have to settle for "Velor' Use a true Black Velvet....one that has no stretch, nor Flocked backing. BV is the epitome of class, and be absolutely certain that anyone touching velor isn't a'gonna say; "Oooooh...Ahhhhhh" like they will touching Black velvet.

Besides that, Black Velvet simply outclasses any Velor as far as masking performance. So don't pull up short...make us even prouder of your accomplishment than we already are!

To quote James T. Kirk;
"I'm laughing at the superior intellect"
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post #4 of 11 Old 08-09-2012, 07:17 AM - Thread Starter
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Thanks for the comments!

Well, I actually am an engineer cool.gif but I wouldn't say may little project is "meticulously" planned.
I keep running into problems here and there, especially the damping mechanism while lowering the thing is still a concern, also fixing the hinges into my concrete ceiling didn't go so well yesterday rolleyes.gif but I'm getting there I guess smile.gif

PJ-wise it's mostly a tight race between the Epson and the JVC:
The Epson has more flexible lens shift options and is brighter (though I don't think by that much when calibrated), but lens shift is manual and regarding my screen with the masking roller blind I will have to move the picture down when changing from 16:9 to cinemascope.
The JVC has motorized zoom and lens shift with lens memory, that would be perfect for my screen. Also it's black are better but I'll have to compare them on a low-gain grey screen, I don't think there will be much difference remaining under those conditions.
The Epson is also shorter and I can more easily fit it in the rack I plan to put behind my couch. The mitsu for example is quite huge is this regard ...
I wonder why you are ruling out the mitsu? I heard it has the best lens and build quality in it's price range, but it probably loses to the other two in terms of light output. Also the zoom factor is a little tight for my projection distance, the Epson and JVC are wider in this regard.
I'll just have to compare them and see what kind of deals I can get around here, especially with new models coming up with IFA/CEDIA and possible price drops for the current models.

I'd like to use black velvet but it would be much more work. The velour I got is already adhesive on one side so I can easily apply it to the frame, also it's width is perfect for wrapping it around like depicted above.
It looks and feels pretty good though and a friend of mine also used this kind of velour for his screen with great results. Also the slightly "stretchy" properties compared to velvet actually help me on the diagonal part of the frame. I'll try to take detailed pictures, maybe the velour you get in the US is different, it can be made of different fabrics after all ...
But I can change it anytime if I also feel it looks cheap or wears of quickly... I will be touching it frequently to lower and lift the screen so it should be "sturdy". Velvet is more expensive and harder to process but I believe you that it might look better, but the "black-out" capabilities are also very good with the velour I got. A lot of people also use the black cotton fabric they use on a stage, but mostly for draperies or the ceiling.
For the latter I got black paint but I might try it with velour or velvet first just to see how it looks before applying paint permanently. That's another advantage of this kind of fold-up screen, you can paint the part of the ceiling under the screen without spoiling any of the living room interiors as this part is not visible in "lamp" mode. It not a big surface but it might help quite a bit with reflections.
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post #5 of 11 Old 08-09-2012, 07:55 AM
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I will be following this!! I am building a folding mount for my fixed frame screen as well right now except not disguising it as anything when it is folded. So far I have built my frame out of aluminum square tube. Working on the hinge system right now and if my Jamestown screen will ever show up I can get it mounted and tested.
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post #6 of 11 Old 08-13-2012, 02:07 PM - Thread Starter
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Well, a little update before the major work is continued:

I had two little setbacks ... while trying to screw the hinges into the concrete ceiling I seemed to have drilled the hole a little too small and I used too much force or leverage screwing them in. Well, one bent, the other broke rolleyes.gif so I got me two new ones and will probably have to drill the holes again, a little bigger this time. Nothing that can't be resolved though.

The other problem I had was the motor. It's torque seems to be too little to directly pull the masking blind up (due to it's weight distribution and radius). So a friend of mine kindly reminded me that I could build a transmission to increase the torque, which I did:



Engineering FTW! biggrin.gif
Now everything runs smoothly, also because the motor runs better at the higher speeds now necessary. The disadvantage is the increased complexity of the construction with two brackets and that the motor is placed even further toward the edge where it will bulge more through the velours later, but at least it works without buying a bigger motor and according power supply.
The cleanest way to do this would be to shorten the metal roll of the roller blind and place the gears to the inside of the bigger bracket, omitting the small one I now use for the motor, but now that everything works I'm kind of hesitant to change it again wink.gif

So next up is fixing the whole thing to the ceiling and also trying out the gas-springs for lowering and damping the frame. I'll try to do this wednesday along with fixing the screen to the stretcher frame and the whole thing inside the outer frame.
Finishing up (probably on the weekend) with the velours and creation and connection of the "lamp". Stay tuned ...
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post #7 of 11 Old 09-03-2012, 06:32 AM - Thread Starter
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Sorry for the long time without an update, but here it comes.
I'm actually on vacation right now but I managed to (almost) finish the project before I left.
So here's how it continued:

After the outer frame was basically finished (minus the velours) I started to build the actual screen using the stretcher frame.
I was going for the sturdy version of the frame with the outer part being 50mm wide and 40mm deep and a double-cross in the middle for increased sturdiness as it's going to be in horizontal position most of the time (on the ceiling). These types of frames can be easily put together. You start on one corner with a long and a short side. Then you fix the parts of the crosses to each other (in my case with small screws) and put the double-cross in the half finished outer frame. At last you put in the remaining two outer sides and fit everything tight (e.g. using a hammer). The tension of the actual screen will make everything perfectly stable later.



Next I placed the frame face-down on the backside of the grey screen. I wrote earlier that I'm using a quite thick high-quality grey screen with a gain of 0.61 from a company called "Gerriets" in Germany. I left enough overlap on the outsides of the frame to allow the screen to fold around the frame to its back where I fixed it with a stapler. On these kind of frames you usually start fixing the screen in the middle of one side, working towards the corners, always stretching the screen. Omit the corners themselves for the very end and continue with the opposing side of the screen. You have to really stretch the screen with a lot of tension so there won't be any folding or waves in it in the end, though the stretcher frame allows you to correct any of those by spreading the screen edges with small wedges. Continue with the remaining two sides always from the middle towards the edges and finally stretch and fix the edges so the screen is absolutely plane. It's a lot easier if you have a friend helping you with this.



I then put the aluminium tape on the inside of the screen and taped the LED stripe onto it, facing to the inside. With the alumnium I hope to increase the reflections and together with the LEDs facing towards the inside of the screen the light should be nicely diffused without any individual LEDs being noticable afterwards. Finally I soldered the power connector for the LEDs to the leads and the screen/lamp was finished. I temporarily put it inside the outer frame for a quick look:



Before I could go on with applying the velours to the frame, I had to get out the router again to provide the space for the gas springs inside the frame. I also fixed the gas springs to the ceiling in their final position allowing them just enough space for their movement from the horizontal position on the ceiling to the extended position when the screen is down. I'll describe further down how the gas springs will be fixed inside their proper space in the frame.



Now it was time to mask the outer frame in the black velours. The DC-Fix velours I got came in a long and 45cm (17.7 in) wide roll which turned out the be the perfect width to go all the way around the frame (as pictured in an older post above) and overlap the beginning edge by just about an inch to allow me to staple it together for increased tension. I started with the top and bottom parts of the frame, going from the inside next to the squared timber around the inner edge, the front, the outer edge onto the squared timber and down again to where I started. I fixed the overlapping edges of the velour with staples to maintain the tension from the outer edge to the timber which will be the main visible part of the frame when in "lamp" mode on the ceiling.



On the bottom part of the frame I fixed a closing bolt to the timber before going around with the velour. The bolt will hold the stretcher frame in place as I will not fix it permanently to the outer frame but rather with hinges too (see below) to allow me to easily change the screen or stretch it some more anytime in the future. Before I finally wrapped the velour on the upper edges of the frame, I drilled a long hole sideways into the frame from the outside through the space for the gas springs and into the frame again. Using 120mm screws and some black spacers, this will allow me to fix the springs to the inside of the frame (as seen in pic 3) and make them completely invisible in "lamp" mode. After wrapping all sides of the frame in velour I hooked it inside the hinges on the ceiling and fixed the springs to it as described above. So the finalized outer frame looked like this:



You can also see the flat building wire connected to the two transformers for the LEDs and motor on the back of the frame which will later be connected to the two-phase lamp outlet in the ceiling. This will allow me to continuously provide the motor driver with power from one phase and enable me to switch the lamp on and off using the other phase. You could also use a one-phase outlet to continuously provide power and switch the lamp by relays controlled by the motor driver or other controllers all available in the TinkerForge system.

Here I'll take a quick break before I continue in the next post with the steps for building the lamp cover and finishing the screen and unfortunately the problems that still remain to be resolved after my vacation rolleyes.gif
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post #8 of 11 Old 09-20-2012, 12:21 PM - Thread Starter
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Well, the break was not so quick after all, I got a little sick on our mini honeymoon.
But now let's continue with the (up to now) last part of the build - the lamp cover:

For the outer frame of the lamp cover I used decorative MDF wood usually used for the finish of floorboards on the edges. It's in mahogany look and serves pretty well as a simple but beautiful frame for the lamp. The cover itself will be done with japanese Shoji paper, a milky, light put sturdy paper used in the well known japanese screen doors.
I started the cover by cutting the sides of the four frame elements in exactly 45° angles so two adjacent frame parts combine perfectly into a 90° corner. I used flat 90°-brackets and very short screws to fix two frame parts into a corner. This is not very sturdy by itself but will be ok once there's tension created by the shoji paper and the frame is fixed to the squared timber on the outer frame.
Unfortunately I could only find Shoji paper on rolls of 94cm (37 in) width, so I will have to use two lines horizontally. To be able to fix the Shoji paper properly and with tension to each other int he middle, I fixed a decorative wood strip to the finished frame, dividing it horizontally in the middle. I painted the strip on the front in the approximate color of the rest of the frame.



With the wooden parts of the lamp cover finished, I proceded to fix the Shoji paper to the frame I much the same manner I fixed the screen to the stretcher frame. To prevent tear-out of the paper where it's stapled I used a narrow belt that's commonly used in roller blinds, rolled into the edge of the paper, and stapled through all those layers into the wooden frame.
Again, work from the middle of one side to both corners first. You should start combining the paper edges in the middle first to prevent waves in the paper when pulling it to towards the frame. I had started on the outside but had to redo a lot of the first side again after I finished the middle section.



After the "five" sides are fixed and stretched, finish on the corners. This type of paper can take a lot of tension, so the frame looks nice and flat once finished. As I had some velours left, I decided to finish the inside of the frame with it to hide the staples etc, though they probably won't be visible anyway. But the velours also minimizes light spill-out from the lamp.
The fnished lamp cover finally looked like shown below. There's still some weaviness left because the decorative wood stripe in the middle is quite flexible and bends with gravity, but I'm quite content with how it turned out it the end.



I was drilling small holes in the four corners of the frame (basically where the 45° edges meet and the brackets have their corresponding hole) and two additional holes in the middle of the longer sides (top and bottom) of the frame. In the corresponding position in the squared timber on the outer frame I screwed special screws with a thread for wood on one end and a machine thread on the other end. The lamp cover goes on the outer frame with a distance to it of about 1cm (using black plastic spacers) with the end of the screws sticking out of the frame on the front/lamp side. I used decorative handles usually used for drawers that I screwed onto the protruding screws (the thread has to match of course) and thus fix the lamp cover to the frame easily. Using this method, the fixing of the cover is nicely hidden and the the cover can easily be removed to allow access to the screen/stretcher frame (in case I want to change it or increase the tension).

Unfortunately the magnets I got to keep the swinging edge of the screen on the ceiling are too weak so I can't currently keep the screen in "lamp" mode on the ceiling. So I can't provide photos of the finished screen in lamp mode yet. But stronger magnets are on the way and I will also create a locking mechanism as the screen has become quite heavy and I don't want to risk it swinging down from the ceiling inadvertently. But other than this setback that I'll fix soon, the screen is pretty much finished and looks like this in "movie" mode with the masking lowered to approx. widescreen format:



I'll of course also take some photos of small details of the finished project and how it looks on the ceiling with the lamp on once the holding and locking mechanism is finished.

Projector-wize I got a great deal on a used Epson 8500UB (TW4400) that I'll probably take. I'll get it for half the price of a JVC RS45 (X30) with warranty etc, so I figured I can use the money saved by the deal on a 4k or similar machine in the future... 2D-wize it should be pretty much on par with the 6010 from what I've heard.
The big light output combined with the grey screen and the flexibility by the wide zoom and lens shift range should be perfect for me, especially since 3D is of no interest to me.
I'll definitely post pictures later!
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post #9 of 11 Old 09-23-2012, 06:08 AM
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Nice! I'm looking to do something similar to what you are doing. Post a youtube vid of it in action also.
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post #10 of 11 Old 09-24-2012, 08:16 PM
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Looks GREAT. I'd be interested in a video eventually too. cool.gif
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post #11 of 11 Old 09-30-2012, 03:35 AM - Thread Starter
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Thanks guys! The masking is still not ready for a video as it's not programmed yet, but eventually I will try to capture it in action.
The rest is manual and thus not very spectacular in a video wink.gif
Here's a construction I would have done similarly if I would have built a dry ceiling (the forum is German but I guess the pictures speak for themselves):
Tiny url: 9zmahpw (it seems I can't post the link itself)

But here are some updates of what I've done last weekend on my humble construction:
I got the (way) stronger magnets (about 120 pounds of holding force), but they are of course bigger (about 42mm/1.65in diameter), so I had to enlarge the two holes on the corners. I won't be using the third hole in the middle anymore.
Due to the larger holes I had to drill, the masking around the holes is not perfect anymore, but that's no problem as I'll explain below. Due to the larger magnets I also had to get bigger counterparts on the ceiling. They are like washers(?) with countersunk holes to fit the screws and allow for a perfect connection with the magnet. I left a little air between them and the ceiling to allow the washers to move a little and fit perfectly on the magnets.
I got four magnets in total and due to the height of each (about 9mm) and the depth of the holes (16mm) I thought I'll use two magnets stacked in each hole. This will also increase the holding force by about 30% (but not double it of course).



So I tried it out and alas, the whole thing worked perfectly and I could finally see the finalized lamp in action:



Here's a detailed picture of the small drawer handles I used to fix the lamp cover to the screen:



Then i realized it was working too good. I could hardly get the screen away from the ceiling. The magnets are really strong, especially stacked! So that allowed me to cover the magnets with velours and make them disappear inside the masking, effectively making them invisible and unobtrusive when watching movies (regarding reflections etc.). With this extra layer of velour between the magnets and their washers, the screen still sticks to the ceiling pretty strongly, but I can pull it away more comfortably.

So what's missing for a nice movie night with the new screen? A suitable projector!
As mentioned before, I got my hands on an Epson TW4400 (the 8500ub in the US) for a very good price through a user in a German forum. This projector has a lot of light output (for the 0.6 gain screen) and the flexible lens shift options allow me to position it exactly how I want it. As the new furniture has not arrived yet, I provisionally installed the projector in my current living room, moving the front speakers towards the corners so they're not covered by the screen. I set everything up perfectly, fed my HTPC with a nice Sci-Fi classic on Blu-Ray and enjoyed my glorious new way of watching movies:



But of course there's still room for improvement. Not really visible on above picture are the heavy reflections on the white ceiling in bright scenes reducing my contrast substantially.
So I'll have to mask the ceiling in an area below the closed screen in black. My wife didn't agree on painting it black and I also think that using some kind of cloth will result in better blackout than using paint.
I already ordered black cloth commonly used in home cinema applications that I will staple to the upper edge of the screen on the inside and I'll use grommets on the other two corners to fix the cloth on the opposing end on the same screws I use for the washers/magnets.

This last step shall conclude the construction for a while before I'll get into programming the motor driver for the masking roller blind.
One problem remains for a while with the dampers. I correctly calculated the pushing force required to keep the screen in a 90° angle, but the force required to dampen the swing-down movement is way to high for the current dampers due to the very long leverage from their point of "attack" to the screen's center of gravity.
To solve this, I will probably have to order special, stronger dampers to keep the screen from swinging down to rapidly. But due to the huge force needed theoretically (more than 4000N), dampers strong enough would probably rip out the screws from the ceiling or the screen.
So I'll settle on weaker damping and focus on braking the movement in the last part of the movement (where the force needed is substantially lower due to the angle). It's always a difficult decision to balance out all the applying forces. To do it perfectly would probably require a wire rope hoist mechanism, but I would never be able to hide that invisibly without a dry ceiling. So I settled on the compromise I can best live with, even if that means opening and closing the screen manually using some force. If you can pull off creating a dry ceiling for your screen project I'd suggest the mechanism the guy uses in the link I posted in the beginning of this post.

After the first movie I can say I'm really content how it all turned out. Now I just have to get the masking on the ceiling and the automated roller blind finished and finally lie back and enjoy smile.gif
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