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.
There's a proper time and place for spontaneity, dammit!