I got the idea to use the large pulley approach from JARathje's 2 way masking design
. The rotor doesnt have tons of power, but it doesnt take a whole lot to operate a traverse curtain rod either. There really arent any forces to work against other than a little friction. There are no springs or weights.
Right now the masking panels arent all that tight. they are just panel track curtains from ikea
I used some cheap velvet from joans for the fabric to test. there is an aluminum strip along the bottom to help keep the fabric in form. but it doesnt do a very good job on heavier fabric. i plan to turn this into a frame similar to a window screen frame to wrap the fabric around.
Instead of attaching the pulley directly to the ROTR100 like JARathje did, I used a drive shaft... actually... its a curtain rod:
I was hoping that i could use the plate on the end of the rod to run some screws into the pulley. It might have worked, but i had to tap the bearings on to the shaft and apparently that plate isnt attached to the rod very well.... so i ran some 3 in deck srews into it instead:
I didnt take any pictures during the assembly, I was too concerned about getting it done! Heres some pictures of the completed drive assembly:
And in place on the left side of the screen. Its just sitting there now, not permanently mounted, and it will move at least a little from this position due to a few issues.
I cut a notch in the wheel and just tied a knot in the curtain cord:
I might make the notch a little wider so the cord slips out in the event that the wheel turns past the range of the curtain track. That way there is no catastrophic destruction. 2.35:1 is with the notch on the far right, 4:3 is a 180 degree turn on the left, if it would turn past that, it would cause the cord to tighten and could cause damage if there were no failsafe.
Here are some screen shots of my iphone web interface:
when the buttons are clicked it invokes in event in eventGhost to set the masking or lighting scene using IR commands sent through the USB-UIRT attached to my server. I dont use the built in presets, instead i have the server send the degree of rotation to the ROTR100. so for example if i select 2.35:1, the server sends:
ESC, 0, 0, 0 to the ROTR.
16:9 it might send:
This will make it easier for me to set up the stopping points, since the rotor controller will be out of view. I can make changes directly in eventghost. the ESC command ensures that any rotation in progress is immediately stopped and the new command executed without delay.
There are still a few issues I need to address. First there is a little bit of play in the whole system. If i extend the masks to 16:9, then go back to 2.35:1. the rotor turns about 3 degrees before the masking starts to move. This is due to a slight stretch in the traverse rod cord. I may mount the rotor above the screen to shorten the cord to reduce the stretch or possibly replace the cord with some sort of cable with less stretch. There is also a little bit of play in my fabulous wooden block connection between the traverse rod and the panel track.
I plan to replace this with a metal bracket of some sort.
The next issue is that of noise. This contraption is not quiet by any means. The ROTR100 is pretty loud. That was another reason for using a drive shaft. I plan to build a box around the rotor, pack it with insulation and then place that box inside the corner bass trap to reduce the noise.