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My Screen Lift System. Some Photos.

post #1 of 28
Thread Starter 
Hi

I finally got around to borrowing the camera from work. Here is a small collection of pics of my DIY screen. I haven't stretched the cloth over the frame yet, that'll be tonight. Also, I have some Sportlite Nylon that I bought in Ottawa, at the suggestion of (name?) another thread. Thanks for that tip. I haven't compared the screen to other cloths, and I will eventually, but for now I'd have to say I'm pretty happy with the white nylon. It seems to keep a failry even intensity at angles from the screen, or it behaves like a 1 gain.

These pics show all the machined parts and how they all fit together. Notice that the cross-arm shaft has to go through a heat duct. I custom-made the last 3 feet of heat duct to keep it shallow (in my joists) but the same approximate cross-sectional area as a 5" round duct, even with the shaft crossing through it. The blue tape patch will be replaced by a metal patch that's removable. It seems to work well and keep my bedroom warm.

There was a ton of work in this, but in the end it will allow me to use the TV for junk viewing and then the screen for bigger events, while having something unique in my HT. I don't really like roll-up screens, so I wanted the framed type. I compare it to landing gear slowly tucking up into the aircraft. It takes about 18 seconds to come down, and I haven't timed the up stroke, but it's about the same. I'll build limit switches into the system so that it's "one button and forget." I'll use the DaLite screen UP/DOWN/STOP Low Voltage Control system to feed the motor. I got one from Ebay, but haven't connected it yet. I also have to add in some relays to make the 1/4 HP motor reversible.

I like feedback and questions, so feel free. I'm also not secretive about this, so if you want some drawings offline, let me know and I'll find a way to do this.

Cheers, Tom, Ottawa Canada.
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post #2 of 28
Thread Starter 
Here's a few more shots of the screen parts.

Tom.
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post #3 of 28
Thread Starter 
Two more and I'm done.

Thanks for looking, Tom.
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post #4 of 28
Very clever Tom

I'm a machine designer and if you are ever looking for a job in the states let me know.

And I don't think you will have to worry about your mechanism wearing out. Finally someone built a screen that rivals mine for weight and strength. But mine just hangs from the wall but is constantly moving. (about .00001 inches a day is my guess) but it's still very tight. link below in signature

Once again nice joband post pictures when you get it lit up
post #5 of 28
Thread Starter 
Hi Tiddler;

I'm sort of a hobby-rated machinist, and somehow I have managed to convince the "powers" that I should be using the mill and the lathe. I've been working at this aerospace research facility for about 6 years now, and overall, built a ton of stuff, so I guess my inclusion to the machine world is fairly secure. (watch that change tomorrow. They're always whining about who's qualified and who has their machinist's "ticket").

It would be very tough to make this out of wood. Metal such as aluminum, has the advantage of being very strong even though a section might be very thin. Wood would just snap if I were to make a straight substitution in my design. But with some mods and "seat-of-the-pants" engineering, it might be something you could do. It would be tough though, since the screen is lifted up like a cantilever beam, or a sheet of plywood grabbed at one edge and wrist-curled up 90 degrees. Even Arnold couldn't do that. Also, I made this quite accurate, overall, and that means parts are well aligned and run smoothly in bearing seats etc. Again, tough to do with wood. But hey, prove me wrong !!

So, thanks for the feedback and watch a movie. I intend to !

Cheers, Tom.
post #6 of 28
Thread Starter 
Hi Bud;

Thanks for the invite to the good old USA. I'll have to get my passport ! Can you get me working on some missles or something? I'm wild about blowing stuff up, and I like flying machinery.

I like machining stuff too, especially if I've designed it. You too, huh?

I took a look at your screen tensioning system. This is a good plan, with the possible exception of the corners of the screen. But then, you've tried it, no doubt, and if it works, it works.

This is the weakest part of my plan. I went home for lunch today, and also stapled some Sportlight Nylon to the wood dowel frame so we can have movie night tonight. The screen is fairly flat, but not perfect. I thought of a few ways, such as springs, strings, and stretching the cloth on a "rack" like yours, but didn't add it to my design yet. Luckily, if I get a brainstorm, I can just unbolt the old screen and put on a new one. I was originally going to have a welded aluminum screen frame. I still might.

Well, catch ya later, Tom.
post #7 of 28
Thread Starter 
All right, who is this?

I know I'm not the only HT nut at the National Research Council, but I don't know who I'm talking to.

This is kinda neat. Small world, and all that. It's not Steve is it? You drive and Optima, don't you?

Cheers, Tom.
post #8 of 28
Bravo Tom!! That is one nice piece of engineering and fabrication. That's one beefy motor and gearbox. Happy viewing!
post #9 of 28
Tom,

Very nicely done. I've been looking to do something similar although I don't have your skills and/or access to equipment. I wasn't planning on doing a cantiliver design...just one that hinged up and locked in place. Ok so here's some questions:

How's the noise with this motor/gearbox?
Can you provide part numbers & drawings...especially for the motor & gearbox assembly.

Any help would be appreciated!

How about a mpeg/avi of your screen in action?

Steve
post #10 of 28
Thread Starter 
Hi Benven and P51D;

Hi guys and thanks for writing. Steve, I love the ID. I'm a confirmed Merlin nut.

So, the motor and gear box aren't exactly dainty looking, and when you do a bit of math, it makes sense. The screen is very light, but it's being rotated at such a mechanical disadvantage, (from its edge) that it really needs some serious torque behind it. If the screen is 30 pounds, which it might be when I make a frame out of welded aluminum, and it's roughly 44 inches high, you'd need almost 700 inch-pounds of torque to rotate it 90 degrees from its edge. This does not even include the torque needed to lift the beefy arms themselves. My gear box outputs a max of 1200 inch-pounds, presumably before you break a gear tooth or something like that, or overload it in some way, so I felt that I needed the beef.

Steve, the gear box is absolutely silent, because it's turning so slowly, and worm gears are inherently quiet anyway, but the motor creates a bit of unwanted noise. First, on start-up, it "snaps" each time, presumably something to do with start windings engaging then disengaging. Then while cruising it buzzes a little more than I would have preferred. It's a 1725 RPM motor, 1/4 HP, but it has a gear box that drops the output to 40 rpm and around 330 inch-pounds. So really, I have 2 gear boxes.

I think I'll try to mount the motor on some rubber isolation pads to see if the vibration can be kept away from the joists of the HT ceiling. Then I could wrap the whole motor in dense insulation, like Safe n Sound Roxul. I wouldn't care about ventilation. The motor only works for 20 seconds each way, and I wouldn't be concerned about fire or cooling, and Roxul is virtually fireproof anyway.

As far as part numbers are concerned, I don't really have them, but the motor is a Dayton, 1/4 HP, with an output of 40 rpm at 330 inch-pounds. It's from Ebay. The gear box is a worm gear, 60:1 ratio, 1200 inch-pounds output torque, bought at Princess Auto in Ottawa. (Tim Allen would live in that store).

If I can get a digital camcorder, I'll do a short video clip. Also, I don't know how to upload video attachments, or where I can upload them to, but anything can be overcome with will power. I think people who like the pics would really like to see this thing move. It's kind of funky because the arms swing backwards, while the screen swings forwards. This allowed me to push the whole thing a bit towards the front wall and away from a set of can lights in the middle of the room. When you see it, it makes sense.

Well, thanks again, Tom.
post #11 of 28
OK Merlin nut....two more questions.

What is the significance of the number 8102?

And just as important...would you be interested in building another axle assembly, or at least the arms, again and selling them? You could be on to a million dollar idea b/c I have looked all over and have not found anything yet.
post #12 of 28
Thread Starter 
Hmmm;

A test ! Well, 8102 means something. I know there were not as many P-51's as spitfires, (20 or 21 thousand) so here goes. There were a few variants of the Mustang, A's with the Allison V-1710 engine, B's, C's, D's and H's and K's with the Merlin, and I'm pretty sure there were more than 8102 altogether, not even including the Apache ground attack version. So I'll guess that was the number of D models since that was the most numerously produced.

Pretty awesome, huh? Now the confession. I googled it. I might have guessed if the planets were aligned.

On to the arms. Pretty challenging. To make another set, I mean. Somebody else told me to patent the idea, but what an investment just for the patent alone! Plus, it took me almost 2 years to finish what I've done so far, although it was just lunch hours. So you see the challenge.

The parts for this project sure added up too. The gear box, motor, sprockets, chains, shafts, aluminum plate, electronic controls and odd bits, so it's pretty daunting to jump in and do it again.

I have to admit that it would be something to think about if there seemed to be demand for it, but I already spent 20 years in a manufacturing business, so you'd have to push harder than usual to ignite my production flames. Maybe we could work something out on the drawings. Haven't really thought about it that much.

Anyway, thanks again for the response and did I google, er, I mean guess right?

Tom.
post #13 of 28
Tom-

Your contraption is a piece of work! I love it! But one has to ask the question: wouldn't a retractable (roller) design be a bit less engineering with (hopefully) the same results?

Don
post #14 of 28
Thread Starter 
Hi Don;

Thanks for writing. Yes, a roller system would have been nothing compared to this, well, a little effort and engineering. But, I just don't like roll-down screens. I find them flimsy, wrinkled (tab-tensioned, I know) and somewhat temporary looking. Like you just hung it there with little effort (that's also a good thing sometimes !).

So, I literally wanted something unique. Something that has a mechanical movement that's in no one else's HT, and that has a look of home automation or robotics to it.

Everyone who's seen it so far gives me the OOH, AH response, which is nice too. Let's admit it, we build these home theaters to enjoy, and also to showcase to our friends sometimes. That's why we love having guests over for movie night. That's also why we post pictures here too. After months or years of work it's quite natural to want five minutes in the lime light. It was a lot of work, but I really enjoy machining stuff, so there was more reward than just the finished product. The journey was fun too. I like to be challenged, especially when I have five guys telling me that I'll never finish it, or it'll never work.

Hope that sort of explains my mind set, and also hope I didn't insult the million roll-up screen owners.

Cheers, Tom.
post #15 of 28
Quote:
Originally Posted by Tom Kay View Post

After months or years of work it's quite natural to want five minutes in the lime light.


And you deserve it...it looks great. I've always loved contraptions such as this and that's why I majored in engineering. I wish I could do something similar for my screen, but my living room doubles as my ht room so the wife would never let it happen I'm fighting to get some acoustic treatments in there (fortunately the burlap look would go well with the room, so it might not be too hard of a sell).

Once again, it looks great!
post #16 of 28
Quote:
A test ! Well, 8102 means something. I know there were not as many P-51's as spitfires, (20 or 21 thousand) so here goes. There were a few variants of the Mustang, A's with the Allison V-1710 engine, B's, C's, D's and H's and K's with the Merlin, and I'm pretty sure there were more than 8102 altogether, not even including the Apache ground attack version. So I'll guess that was the number of D models since that was the most numerously produced.

Pretty awesome, huh? Now the confession. I googled it. I might have guessed if the planets were aligned.

OK you cheated...That is correct...there were 8102 D models produced. Your punishment is a set the arms & axle assembly!

Just kidding...I understand you not wanting to go through the labor again. Back to the drawing board......
post #17 of 28
Very nice work. I can imagine something similar in my living room that swings down the LCD TV sitting on my fireplace mantle today. It would be heavier at 50 pounds so maybe need to be beefed up some more. What would be really cool though (for my living room) would be to drop the whole ceiling so that the TV and arm and such nested into a cavity. Drywall the back side and probably texture the whole shebang so it would appear out of nowhere.

You could of course do something similar, expecially if you went with a black ceiling. It wouldn't be to hard to make it disappear in a dark room with a black ceiling!

Again, excellent job!

Tboy
post #18 of 28
Ah man.... That is so sweet. I was trying to think of a way to swing down the screen from the cieling or wall in my place. This is so nice though. It would be perfect in my application.
+1 for demand, just need about 998 more people to jump in on this to get you funded for mass-production!
post #19 of 28
Thread Starter 
Hi

I have a new question about this sytem. It's not perfect, not that I really expected it to be on the first iteration.

Everything works as it should. But the motor is mounted very firmly to the ceiling joists in my basement ceiling, with solid hardware, and it really vibrates for the 20 seconds that it takes to lift or lower the screen. I mean REALLY vibrates. My wife gets shaken out of the bed in our bedroom above the HT. Hmmm, I should charge her 25 cents for the ride, just like some hotels....

So, I need to solve this issue, especially if I'm going to watch movies late at night. I thought of building a hush box around the motor, even enclosing around the output shaft. It's an 120 VAC motor with vents in the motor casing, so in theory it needs passive cooling. I called several motor rebuild experts in Ottawa, and they all say that if I'm running it for 20 seconds, resting it for two hours, then another 20 seconds to put the screen away for the night, don't worry at all about heat. I'll do some testing on this once I build a box.

It's the sound and vibration that causes most of my concern. I intend to "soft" mount it to my joists, using the box, which in turn, sits on a wood plate bolted to the bottom of my joists. The plate would have some soft material on it like wool felt, separating the plate and the box.

Even the box I build would be a box within a box, with soft wool felt separating the two layers of wood. I have heard that sound and vibration really don't travel well through several layers of varying density. I might even line the inner surface of the box with sheet steel to guard against possible (but unlikely) sparks coming from the motor, so they don't drop onto a wood surface.

In short, all physical connections between the box and the ceiling joists would be as soft as possible.

Anyone see any flaws in this idea? Anyone have other ideas? I'd really like to hear some. I think the noise of the motor is minor and solvable compared to the buzzy vibration problem. I suppose I could also consider Green Glue to separate the layers of wood that make up the hush box.

Well, vibration experts, or anyone, please let your ideas fly !

Thanks, Tom.
post #20 of 28
Tom
The duty cycle on a motor like that is based around continues duty and then backed off for interment usage. Running it for that short a cycle would make heat a total non issue in your case. The noise I'm guessing isn't as big of a issue as the vibration and getting rid of the transmitted vibration I'm guessing will reduce the noise. Your floor is acting as a speaker cone in this case.

Use rubber motor mounts of some kind. DIY or store bought would be where I would start any place the device contacts the house.
post #21 of 28
Thread Starter 
Hey Bud;

Funny you should say "speaker cone" since that's the exact analogy I've been using. The whole floor's a speaker cone. It's a hardwood floor above, so no built-in damping, like a nice thick carpet. The motor isn't quite in the middle of the floor, which would probably make it worse, but it's bad enough. Right now, my sweetheart would turn me into a nute if I moved the screen while she's sleeping. Talk about wife-non-acceptance-factor.

She even said it's a monstrosity when she saw it built, before I powered it. Man, talk about a Quasimoto complex.

I think the guesses about heat being no factor are right. I just think over-planning, and assuming there WILL be sparks is a good precaution, so lining the hush box with steel makes sense.

What do you think of green glue for the damping material between the two layers of wood boxes? Better than thick wool felt, or hard to tell?

Using rubber feet to attach the mounting plate to the bottom of the joists is certainly one approach. I have similar mounting feet for the motor on my old Singer industrial sewing machine. I guess they're there for a reason. Where can I get some nice soft squishy rubber?

Thanks again, Tom.
post #22 of 28
Tom-
Try this: www.mcmaster.com.

Don
post #23 of 28
http://www.vibrationmounts.com/

Could you move the motor to the wall with another gear and chain?

You might be able to eliminate your gearbox in your current setup with a worm gear on the shaft. That might help to eliminate extra bits hanging below the ceiling an one less thing to vibrate. Hard to really tell from the pics.
post #24 of 28
Thread Starter 
Hi Don and EAS;

Thanks for the replies. I looked at Mcmaster Carr for some rubber and vibration stuff. I'll have to go through it more, but there's lots to consider from that supplier.

EAS, you asked "Could you move the motor to the wall with another gear and chain?"

Tough to do because I have too little room behind the back edge (or top edge) of the screen. I was lucky to be able to tuck the big 60:1 worm gear box in this location. So other than a few minor adjustments I think the layout is largely set in stone.

Well, thanks again guys, Tom.
post #25 of 28
Very impressive.
post #26 of 28
Quote:
Originally Posted by Baggy View Post

Very impressive.

Indeed, though perhaps a little over-the-top I think.

I want to hinge a screen and lift it manually, stowing it into a ceiling soffit of some sort since it would be "up" most of the time (WAF to be considered here).
post #27 of 28
Quote:
Originally Posted by Laserfan View Post

Indeed, though perhaps a little over-the-top I think.

I want to hinge a screen and lift it manually, stowing it into a ceiling soffit of some sort since it would be "up" most of the time (WAF to be considered here).

Yes me too.
I'm currently using an electric screen because the area I project against has a doorway that I can't block up but would prefer a fixed screen that would hinge down.

You've got to admire the engineering though.
post #28 of 28
Quote:
Originally Posted by Tom Kay View Post

Two more and I'm done.

Thanks for looking, Tom.

Super, Tom. Make sure to post the finished results. Awesome!
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