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See my New Screen Lift Project


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#1 of 10 Tom Kay

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Posted February 09 2007 - 05:29 AM

Hi Folks;

Here's a few pictures of the custom-made screen lift device I have nearly completed. I recently installed this in my basement ceiling, and I will soon install the controls for it.

I want to be able to use the TV for basic junk, and the screen and projector for better viewing. I don't really like roll-up screens, and I wanted something that kind of looks like home automation, that few people would have. This reminds me of airplane landing gear swinging up after take-off. (or hopefully down before landing).

It took me a year and a half of lunchtimes in the little machine shop at work, but it's been a lot of fun. I have powered it several times, and there's no problem with the motor and gear box lifting the weight. The gear box is a 60:1 worm gear with 1200 inch-pounds of output torque. The motor also has a small gear box mounted right on it, and outputs 40 rpm, so overall, the screen moves up or down in about 20 seconds.

The screen frame is made of wood dowels, and plywood flat pieces and I have just stretched some Sportlight Nylon on the frame to make the screen surface, albiet still a little wrinkled. It'll be neat to get the controls all in place, hit one button on the remote and watch it go. Limit switches will stop it at the right up or down position.

So, feel free to ask questions and/or tell me how nuts I am for taking all this time to make it. Cheers, Tom Kay, Ottawa Canada.






#2 of 10 Tom Kay

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Posted February 09 2007 - 05:30 AM

Here's 3 more and that's all I have for now.

Tom.




#3 of 10 wolffcub

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Posted February 09 2007 - 07:04 AM

That has got to be the coolest thing I have ever seen for a HT project. I smell a patent!

Better yet….when can I place my order?

#4 of 10 mustangwally

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Posted February 09 2007 - 08:04 AM

very cool!! i think i may have to try that when i get more time!!

nice job!!

#5 of 10 chuckg

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Posted February 12 2007 - 06:01 AM

My friend, there is something deeply wrong with you.

And we love it!!!!!!

This is the kind of thing I wish I had dreamt up....can you give us some idea how the chains and sprockets work together to make the screen fold one way while the arms move the opposite way? (I guess you must have a non-moving sprocket that I can't see in the pictures. hhhmmm)
--ignore the man behind the curtain

#6 of 10 Tom Kay

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Posted February 13 2007 - 07:34 AM

Hi chuckg;

Yes there is something deeply wrong with me. But I want you to know as well, that I am also very interested in women, well one in particular anyway. I call her my wife, so there, THAT smooths things over nicely, doesn't it?
I'm just a multi-facetted guy.

Yeah, I'm a project-a-holic. My other long term project will take me 4 lifetimes. It's a 1/4 scale Rolls-Royce Merlin engine, hopefully to run, although I haven't worked on it for years since I bought a house (a real project). But I'm happy, so no medication for me, OK?

Any hoo, good guess on the stationary sprocket. There are 4 sprockets in each arm. One big one at the top, bolted firmly to a joist mounting plate. The other three are in the little "boot" at the bottom of the arm. Two of those are on the same shaft and are welded together. The last sprocket is welded to the screen mounting bracket. So basically the big sprocket forces the chain to drag around it and rotate the two welded-together sprockets. This has a shorter chain linking it at 90 degrees to the last sprocket which rotates the screen frame. Clear as dead squirrels, right? I'll try to do a more in-depth drawing one day. But that's it anyway.

The sprocket at the top is roughly twice as big as all the others. 25 teeth versus 12 teeth. This is because I need the upper arm to move roughly 90 degrees with respect to the ceiling, but the screen must rotate 180 degrees with respect to the upper arms. If all the sprockets were the same size, the screen wouldn't rotate at all while being hoisted up by the arms. It would simply stay in its original orientation. This will either make sense or I'll just have to keep my day job and not be a teacher. Again, sometimes it's hard to visualize in your head, but perfectly reasonable once you see it. One day I'll try to post a short video clip of the movement.

So, hope that helps. Cheers, Tom.

#7 of 10 chuckg

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Posted February 13 2007 - 08:38 AM

Perfect - - I was guessing the upper sprocket would be double the teeth of the lowers. I had not envissioned the welded together sprockets and two separate chain approach! I was trying to figure out how you turned the "inside" corner so tightly on the chain! (could be done with fatter arms)

This thing is so cool.......if I ever have a screen, I may have to steal your idea.

thanks! oh BTW - A 1/4 scale Merlin? How cool is that! Is it a kit, or are you seriously afflicted and building it from scratch? A colleague of mine builds scale trains with operating steam engines. He also owns a couple of real steamers.
--ignore the man behind the curtain

#8 of 10 Bud Huey

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Posted August 23 2007 - 03:01 PM

While I will admit that this is really cool and kudos to you for spending the time and effort to come up with such an "out of the box" idea, but I have to ask a question - since you have a projector why would you want to watch anything on the regular TV? It is kind of like watching shows in HD - you never want to go back to SD again!

Kudos again though on the design!
Bud

#9 of 10 joseph westcott

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Posted August 25 2007 - 04:53 AM

What a cool solution! It should be fairly quiet and it really adds a wow factor to the home theater experience. Now you just have to make it where it disappears into the ceiling. Maybe two sliding doors once it is in place against the ceiling rafters.

Makes my folding painting solution pretty lame. Maybe you can help me automate my screenpainting?

#10 of 10 joseph westcott

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Posted August 25 2007 - 04:55 AM

Quote:
Originally Posted by Bud Huey
While I will admit that this is really cool and kudos to you for spending the time and effort to come up with such an "out of the box" idea, but I have to ask a question - since you have a projector why would you want to watch anything on the regular TV? It is kind of like watching shows in HD - you never want to go back to SD again!

Kudos again though on the design!
Bud

Because SD programming still dominates the content world. SD look like garbage blown up to projection screen sizes and you just can't beat the performance of a quality CRT on a smaller screen size.