New masking system - AVS Forum
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post #1 of 18 Old 09-02-2001, 06:38 AM - Thread Starter
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The proof of concept design and installation (doesn't that sound real engineering like?) of my new masking system has been installed and checked out. I really liked Deane Johnson's design but the DrapeBoss motors are no longer available and they were expensive.

It uses one relatively cheap drapery motor , two styrofoam panels, four pulleys, and some cord.

Here's the design:
http://www.lastrange.com/ht/images/maskingSmall.jpg

Pictures of the prototype can be found <A HREF="http://www.lastrange.com/ht/pictures.shtml#mask"" TARGET=_blank>here</A> or by following the pictures link in my signature. The panels need to be covered and positioned and I may need to change the "resolution" on the motor to give me finer control. Overall, it just worked!

Comments welcome.

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[This message has been edited by tlastrange (edited 09-02-2001).]

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post #2 of 18 Old 09-02-2001, 07:11 AM
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This is the most elegant idea I have ever seen. You are a genius. No kidding.

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post #3 of 18 Old 09-02-2001, 09:24 PM
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I agree...it is simple and it works. Great work my man!!!

Wouldn't it be nice if you could also somehow motorize your Model B in a similar way (I'm sure that's not too far away). If you get any ideas, be sure to let us know.

Cheers,

- Sonny B.

[This message has been edited by sonny b (edited 09-02-2001).]

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post #4 of 18 Old 09-02-2001, 09:58 PM - Thread Starter
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Quote:
Originally posted by sonny b:
Wouldn't it be nice if you could also somehow motorize your Model B in a similar way (I'm sure that's not too far away). If you get any ideas, be sure to let us know.
It probably wouldn't be that hard. That little motor has a good bit of torque. You should have seen me last night when I strung the cord and plugged it in for the first time. I had the limit switches set waaaaay too wide apart and it proceeded to unleash hell pulling the panels up to the pulleys and then some. Imagine the knots going through the motor, cords jumping their tracks, small animals and children getting sucked up into the vortex. I'm watching the whole thing unfold never thinking to just pull the power cord... http://www.avsforum.com/ubb/smile.gif

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[This message has been edited by tlastrange (edited 09-02-2001).]

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post #5 of 18 Old 09-03-2001, 06:51 AM
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One quick question though, Looking at your site and the masking, how and with what did you attach the strings to the foam with? This looks great, I plan to do this very soon.
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post #6 of 18 Old 09-03-2001, 07:11 AM - Thread Starter
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Both sides of this particular styrofoam are completely flat. I used sticky velcro strips on both sides and then a longer strip (without the backing removed) as a "strap" that goes over the top. I can use the strap to fine tune the positioning once I get them basically in place.

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post #7 of 18 Old 09-03-2001, 02:37 PM
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Very clever design concept Tom. Thanks for sharing it with us. Hopefully this will help more people to enjoy the benefits of remote control masking.

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post #8 of 18 Old 09-03-2001, 03:03 PM
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This beats the $1500 system I was looking at. I do have a question. My scaler positions the leterboxed image at the bottom of my 16x9 screen. Theefore I only need to mask the top. It looks like your system is dependant on hooking the other end of the cord to the lower masking panel. If I do not need a lower panel, what would I hook that end up to Is the bottom panel acting as balast for the upper one? Or can I just leave the cord dangling?
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post #9 of 18 Old 09-03-2001, 06:54 PM
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Rick,

The two panels do counterbalance each other. If you only use one masking panel you would either need to attach a small counter-weight to the other end of the cord or secure the end to the motor.

Tom,

Nice design! Very elegant, I guess the trick is getting the strings the right length so that the panels hang straight.

If you want a real nice look, you can bevel the edges of the styrofoam so that you get the edge almost flush with the screen. What are you going to use to colour the panels black?

Regarding the "resolution" of the motor you could gear down the whole thing and gain greater resolution (but slower speed, of course). Have two lengths of string instead of the one you have now. One would be a closed loop connected to the motor and a large radius pulley. The second length of string would be exactly like what you have now, except instead of being looped through the motor you would loop it around a smaller pulley that was attached to the larger pulley (i.e. they rotate together around a commong axis).

Regards,

Kam Fung
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post #10 of 18 Old 09-03-2001, 07:44 PM - Thread Starter
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Quote:
Originally posted by KFung:
If you want a real nice look, you can bevel the edges of the styrofoam so that you get the edge almost flush with the screen. What are you going to use to colour the panels black?
I'm planning on covering them with velvet.

Quote:

Regarding the "resolution" of the motor you could gear down the whole thing and gain greater resolution (but slower speed, of course). Have two lengths of string instead of the one you have now. One would be a closed loop connected to the motor and a large radius pulley. The second length of string would be exactly like what you have now, except instead of being looped through the motor you would loop it around a smaller pulley that was attached to the larger pulley (i.e. they rotate together around a commong axis).
That's exactly what I'm going to do. I'm an avid cyclist and this will be just like shifting onto the small chain ring up front and a large sprocket in back to downshift the thing.

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post #11 of 18 Old 09-03-2001, 08:42 PM
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Right on! Let us know how it turns out.

I guess slippage is not really a problem with styrofoam... do you think that will change once you add the velvet?

Regards,

Kam Fung
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post #12 of 18 Old 09-04-2001, 03:19 AM
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Tom,

Great work, this was one project that I was looking to pass on but am now reconsidering.

Two things to note:

1. If you lack wall space on the sides you could use two more pulleys to redirect the lines so they point down (and not to the right).

2. Re: Gearing

Another option, instead of gearing would be to use some pulleys for a mechanical advantage such as shown here.

You'd get all the same resolution gains of the sprocket but with what may be a simpler design. I'm an avid climber and this would be just like a typical crevasse rescue setup. http://www.avsforum.com/ubb/smile.gif


Bryan Nomad


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post #13 of 18 Old 09-04-2001, 06:06 AM - Thread Starter
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Quote:
Originally posted by KFung:
I guess slippage is not really a problem with styrofoam... do you think that will change once you add the velvet
The pulley inside the motor is some kind of rubber so it grips the cord real well. I don't think I'm going to run into slippage with the weight of the velvet.

Quote:
Originally posted by Nomad:
1. If you lack wall space on the sides you could use two more pulleys to redirect the lines so they point down (and not to the right).
I would guess yes.
Quote:

2. Re: Gearing

Another option, instead of gearing would be to use some pulleys for a mechanical advantage such as shown here.
I was thinking more about the gearing problem last night strictly in terms of what I can easily pick up at Home Depot. I was picturing lifting engines out of cars with a block and tackle which is the same concept you use in climbing. Off to Home Depot this afternoon!

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post #14 of 18 Old 09-04-2001, 10:22 AM
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Sometimes I sit around and think of how to solve problems like a masking system. I draw some things up, even try and put together a bill of materials.

After a while I get the bright idea to check on AVS and see if someone else has already solved the problem. Usually that is the case, and its always something better than I could have done myself.

So, thanks much for putting all this together, and taking the time to post it on the web.

Now, I'm off to work on moving heavy objects on a level surface. Right now I'm using skids and placing mashed potatoes under the skids to decrease the friction. This ends up being messy and a little expensive. One day I'll figure out a better way . . . . http://www.avsforum.com/ubb/wink.gif

Kelly
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post #15 of 18 Old 09-04-2001, 11:55 AM - Thread Starter
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Quote:
Originally posted by kstirman:
Now, I'm off to work on moving heavy objects on a level surface. Right now I'm using skids and placing mashed potatoes under the skids to decrease the friction. This ends up being messy and a little expensive. One day I'll figure out a better way . . . . http://www.avsforum.com/ubb/wink.gif
Sounds like you're trying to recreate pyramid construction http://www.avsforum.com/ubb/smile.gif



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post #16 of 18 Old 09-21-2001, 12:21 PM - Thread Starter
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Well folks, sorry but I'm not going to get this project completed anytime soon. I got caught in a dotcom downsizing and will be uprooting and moving east to Delaware.

The screen's coming down and the projector is getting boxed up this weekend. Not sure when I'll be back.

See ya.

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post #17 of 18 Old 09-22-2001, 04:29 PM
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For Europeans, the whole thing can be done using the readily available hardware for electric blinds (Rolläden). I did this in my cinema and it works out great at a cost of approx. $ 150 for everything.
Don't have a picture handy but the general idea is using a hollow steel tube with an AC motor inside, mounted atop of the sreen. These motors are so slow that they allow very fine adjustments. The tube carries the fabric that unrolls in front of the screen from above (needs very little room above the screen, in my case only some 4 inches). The tube is made a bit longer than necessary and carries a thread on each side on that extra length. That thread is running down to another piece of tube (just 1 inch dia) that carries the lower fabric. When you unroll the upper fabric, the lower one gets lifted up and vice versa. That way you can adjust to any aspect ratio you want.


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post #18 of 18 Old 09-24-2001, 04:22 PM
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Thomas: this is very interesting. Does Rolladen have a web site or email address? I would like to contact them and see if their equipment is available in Canada.
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