CIW Electronic Masking: DIY and very easy :)

So I wasn't sure where to post this, but figured people would see it here. I know there is a lot of interest in electronic masking and the other day I built a system for myself. The building of the project only took the better part of a day. I thought about the project for weeks, but the building went smoothly.

Here are photos of the screen open at 178 and closed at 235. There is also a linked video showing the screen masking motion in real time.





VIDEO Download
http://www.cir-engineering.com/bin/masking/masking.wmv

I got most of the parts from www.av-outlet.com Here is a parts list of what I got from them.

• Somfy LT30 IR Round Head 1.25" 12VDC Roller Shade Motor.
  Somfy LT30 - IR1 - Single Channel IR Remote Control (Required for programming stops).
  Three Rollease RB360 Shade Brackets.
  Two Rollease REP03 End Plug for 1.25" Tubes.
  AVO 12VD100W - 12VDC 1A White Wall Plug Power Supply.
  Rollease SAPE03-RIGHT Pin End Spring Assist - 1.25" - RIGHT.

From HomeDepot I got a couple 2x4's, some aluminum "U" channel, Velcro, pulleys, screws, Gorilla tape, drywall anchors, and other odds and ends.

I went to a metal shop near me and got 1.25" round tubes for the rollers and 0.5"x1" rectangular metal tubes for the masking bars. Please note: You CAN NOT use a ferrous tube for the motor tube. This motor uses magnets to know where it is, and to memorize the stops positions. If you use a steel tube, your motor will not work correctly at all. You must use an aluminum tube for the motor tube.

I went to a craft store and got some black fabric for the masking.

Here are more photos.

Top Right 178




Bottom Right 178


Top Right 235



Bottom Right 235



Top Left 235 (see wound up cables)


Bottom Left 235


Cable to Masking Bar


I got many original ideas from this thread on AVS http://www.avsforum.com/avs-vb/showthread.php?t=1219694.

Here is a quick explanation...

The motor goes inside the roller tube at the top right. The tension spring goes in the roller tube at the bottom right. The top and bottom round tubes are attached with the brackets and plastic bearings from av-outlet to a 2x4.

The fabric is taped to the round tubes with Gorilla tape. The fabric is wrapped twice around the masking bars and is again taped to the bars with Gorilla tape.

The top mask falls by gravity as it unwinds. The bottom mask is pulled up by coated metal cables attached to the bottom masking bar. The cables wind up around the top round tube. The cables are held to the top round tube with hose clamps and are held to the bottom mask bar by wire fasteners (available in the electronic section of HD).

The spring in the bottom right round tube pulls the mask back down when the mask is opened. The motor pulls the top mask up when the mask is opened.

The "U" channel holds the masking bars at the sides. I wrapped the ends of the masking bars with Velcro so there would be a smoother motion of the moving parts.

A 2x4 is anchored into the drywall about 2.5" from the boarder of the screen. These 2x4's hold the roller tubes and all hardware.

I would estimate that the entire project cost around $400.

Questions?

craigr

This project was totally easy compared to how difficult I thought it would be. I mean, I thought about my design for at least three of four weeks. I ordered the parts and they sat here for another week or two. But when I finally started building it only took me about five or six hours to have the entire thing almost complete.

I had two complications. The first was that I originally used a round steel tube for the top mask with the motor inside it. The motor would not memorize the stops, and when I would do a factory reset on the motor it would freak out and unwind my entire system and everything would fall all over the place (lots of very loud cursing would follow). After this happened at least six times I was annoyed.

This was a Friday evening so I had to wait until the following Monday to talk to AV-Outlet about what I thought was a defective motor. When I talked to Ken at AVO he discovered that I had used steel and told me that was the problem. A few days later I got an aluminum tube and the motor worked perfectly.

Unfortunately, when I took the bearing out of the old steel tube it broke, so I had to wait four more days to receive a new $3 bearing that cost $6 to ship :roll: However, after that I was good to go.

The hardest part is getting everything wound up. Remember, the bottom is on a spring and is always under tension.

Winding up everything is easier with two people. I first did the bottom mask and started by attaching the fabric to the rectangular masking bar with the parts on the carpet laying in front of the screen. I then slid the bottom masking bar (and fabric) in between the channels on either end. I held the bottom masking bar well above the 235 position and then attached the green steel cables to the bar. I pulled the cabled (one at a time) up to the top roller tube and wound them around it five turns (I had calculated four would be enough 2*pi*R). Make sure you wind the right way or you will obviously have serious problems. With the cables in position I clamped them down with the hose clamps.

I then pretensioned the bottom sprig by rolling it up about twenty turns. I attached the fabric to the bottom roller tube with the Gorilla tape. Once the tape is on and the cables are fastened the system is under tension and will hold its self together...

...level the bottom masking bar by adjusting the cable lengths, and then move onto the top...

craigr

What about them? Do you mean how are they finished?

The photos were taken with the system open so you could see the workings. Two strips of trim cover everything up so that you normally can't see it all. The trim goes from the 2x4's just past the black screen boarder.

craigr

Thanks

craigr

Lots of good questions...

Firstly, there is an "open" and "closed" stop position that can be memorized with this motor. Open is for 178 and closed is for 235. I only have to press the "UP" button and release to close the screen down to 235. And I press the down button and release to open back up to 178.

So the motor has an integrated system for memorizing stops built right into the motor. The motor I used is IR, but it is also available in an RF version. You can also get an option to integrate Crestron or AMX.

Below are the instructions for setting the motor stops for the IR model.



You can also jog the motor and there is also a third stop position refereed to as "My Position." I have not tried the "My Position" option yet, but I should be able to use it to create a stop for both 235 and 240 seperateally.

Right now I just watch everything with the screen fixed at 235. So for 240 movies there is a thin black bar at the top and bottom of the screen. I plan to either use the "My Position" for this, or I plan to make the 235 stop into a 240 stop instead, and just use that for all wide aspect ratio movies (I will also use blanking to crop the image slightly on movies that are taller than 240).

The fact that the stop positions are memorized inside the motor is one of the things that makes this masking system so simple. The motor is the key because you don't have to design anything additional to automatically control the motors operation and to have fixed stops.

craigr

You are welcome

I have seen lots of DYI masking threads over the years, but most of them seem to lack enough photos to get a good idea of what is really going on. I figured a picture is worth 1,000 words, so here are 14 pictures to help you design your own

Yes, you only need one tensioner spring in the bottom right with this design. The roller tube is perfectly rigid, thus the force from the spring in the right side of the tube is perfectly distributed to both sides of the bottom tube. Both the left and right (and entire) tube is under tension with the one spring.

On the left sides of the top and bottom roller tubes there is a plastic roller bearing. The roller bearings are in my parts list along with the brackets to hold the bearings to the frame.

craigr

You are welcome to my ideas so you don't have to steal them

I designed my system before I spoke to anyone at AVO. When I finally did talk to them, Ken told me that 1.25" poles were technically too thin for a span as wide as mine (nearly 108" with screen frame). Ken suggested that I should have used 1.5" tubes, but that my system would probably work fine because the travel distance of the masking is less than 14" total. Had the travel been longer, the fabric would probably have folded and wrinkled due to deflection of the 1.25" tube.

I would suggest that if you go larger than 108" width, you may want to use 1.5" tubes instead. You can order the motor I used in a 1.5" version, and there are also other motors available in a 1.5" version. Just remember that if you go to a 1.5" tube that you also need 1.5" bearings and a 1.5" spring instead of the ones I listed. They are all available at AVO.

craigr

Thanks.

This motor is relatively loud, however it is not bothersome in person IMHO. If you have ever hear the ISCO anamorphic lens engage, my masking system is not quite as loud as the one used by ISCO for their lens.

We had some people over for a movie the other night and it was the first time any new people had seen the masking system. When I hit the button the crowd went wild with lots of "oh my gods" and ooooos and ahhhhs. I think the volume of the motor is just right for this

There is also a higher end motor available, the Somfy Sonesse ST30. This motor is quieter, stronger, has more capabilities, and only comes in a 1.5" and 2" versions. The ST30 is also more than $100 more expensive than the LT30, which is why I opted NOT to go that way... I wanted to see how cheaply I could build a quality system.

craigr

BTW, I did replace the burned out light bulb in the center of my pic

craigr

Of course I remember you Floyd

craigr

Thanks John,

The system is still working perfectly and I have not made any changes or adjustments to it in months. I have been planning to use a darker velvet fabric instead of the felt that I started with. I swapped the bottom mask with the black velvet months ago and still have not gotten around to redoing the top mask to velvet.

...maybe I will make that a new years resolution

craigr

I think for CIH you could have a strip of black on each side that gets rolled all the way down from the top...

craigr