Originally Posted by TeeCue
Great plan, beautiful drawing!
I have been looking at a similar option that goes something like this:
1) Use a SCREW DRIVE garage opener as the main motor. You only want to use a unit with a DC motor in it.http://www.geniecompany.com/GenieCompany.aspx?cid=560
These are very quite specially when there is not a lot of load on them. The power supply can be modified to be used with outboard reversing and limit switches. You dont need the internal control board and receiver board (?sell them on ebay
2) The aluminum track will be used along with the carriage.
3) The track comes in short lengths and extensions are available to get the desired length.
4) Get an extra carriage (or make your own) and screw it from the opposite end so that when the screw rotates both the carriages meet in the middle.
The front ends of the maskings can be connected to the carriages in such a way that the front ends remain perfectly straight and vertical so that there is no need for a bottom screw drive!
I have always been a proponent of using weights to maintain tension on the masking. This will work great.
A BELT DRIVE unit can also work, but I like the Screw drive better.
I am a little busy these days but will try to make a diagram of the masking to carriage connection.
I see a couple of possible problems.
1) screw drive openers only come in one thread direction. This means that to work you would have to use a motor on each end. One turning forward and one turning backwards, the screws can't be connected beacause they have to turn opposite directions. So some how you would have to get each motor to start and stop at exacty the same time and run exactly the same speed to stay in sync with each other. Or you would have to use seperate position sensors and controls on each one.
2) you are going to need screws top and bottom I think to keep the masking edge square to the top and bottom of the screen. You have to remember that you are going to have the tension of the masking pulling on that leading edge trying to bend it to the outside edge of the screen. I don't think you could ever brace it enough using only a top or bottom screw to keep it square.
3) shortest door opener is 7' so you are going to have to cut it of, unless you have a 14' wide screen. And like I said earlier you would need to buy 2 of them atleast.
I look at this option also and just came up with too many problems or possible problems down the road. Plus it is no cheaper when you really start figuring it out.
As far as motors go you can use 120v, I am going to use a 1/3hp 120v motor that I had laying around out of a furnace that is reversable and very quiet. I will be using a rotor control that will alow you to program in 99 memory positions for different screen sizes. The rotor out put 19volts which is will use to trigger a relay that is triggered by DC and switches AC to the motor. A timing belt will transfer power to the upper screw, so the entire thiing is controlled by one motor. The ony way it can possible get out of sync is if one of the dowel pins that I have connecting the screw shafts was to shear off, and I don't see that happening.
ScottJ0007 has a very good thread that explains how to use the rotor: http://www.avsforum.com/avs-vb/showthread.php?t=941076
Never mind I should have looked at the name first, you know all about the other thread......good work