DIY Main Curtain Motor?

[noozer42]

Hello All,

I hope I'm posting this in the right place. I work in a small theater space with little to no space in the wings. In order to open and close the main rag, a stagehand has to huddle against the wall on SR for a whole performance. I'm wondering if anyone has any advice on DIY'ing a system to make the main rag remote controlled from the booth. I'm imagining a small reversible motor with a rubber wheel on the spindle that can clamp onto the rope by pressing against another wheel. A switch in the booth could set the motor to one direction or the other, and a simple pot could control the speed. There isn't a lot of budget to put in a fancy motor-controlled system, and I feel we could put something like this together for much less than a grand. Am I way off base? Has anybody tried anything like this before. Several searches along these lines have given me plenty of info on professional motor control systems for theaters and homes, but nothing really along the lines of cheap, simple, DIY. The main rag is 35' by 17' and there is no fly system, just a simple open and close rope system.

Any information anyone could give me would be greatly appreciated, such as the type of motor or switch system. Thanks in advance for your help.

-B

 

[Van]

.... Several searches along these lines have given me plenty of info on professional motor control systems for theaters and homes, but nothing really along the lines of cheap, simple, DIY. The main rag is 35' by 17' and there is no fly system, just a simple open and close rope system.

Hate to be the bearer of bad tidings, but simple, easy,Cheap and DIY don't get along well with the word Motor Control. As a matter of fact the words should all remain as far away from each other as possible. the way a "real' motor controlled traveller works , typically, is a drum around which the rope turned several times, is driven by a gear motor. In a good system the gear motor has internal load limiters, in case the curtain gets bound up the limiters will shut it down. It will also have a proportional driven limit switch for setting maxiumum open and close settings. Working the control into everything < having push buttons back stage as well as in a booth> begins to get a bit complicated unless you know what you are doing as far as mapping out such systems. There may be a supplier on here who could hook you up with a "bolt it in" system but I kinda doubt it. You could build a system with parts from Grainger or McMaster-Carr but by the time you finished you'd probably be better off just buying a system from a rigging supply company or a motion control house.

 

[noozer42]

Thanks for the reply! That was pretty much what I expected. *sigh*... -B

 

[Lambda]

I had actually planned to build a startlingly similar system for our main rag last year. But, like Van said, when you think into it it gets a bit more expensive than "cheap", a bit more complex than "simple", and a little difficult for "DIY".
The real right way to do it is with a gear motor, with a traction sheave that the rope winds several times around, limit switches to ensure it doesn't try to over-open / over-close it and damage it, an emergency killswitch, speed control system (more complex then you'd think, especially for powerful motors), and the PLC to control the whole thing. With the cost and complexity of all of that, if you have the budget, you might as well hire a pro to come in and do it.

It may be possible for you to use a longer rope on the traveler, and use mule blocks to allow it to be controlled from a more convenient location. At our place, the main rag is actually on the house side of the proscenium, with the ends masked. We have the lines for it run through the wall into the SL wing, so it can be operated from backstage.

 

[quesauce]

One other thing to consider is support down the road. Even if you design, build, and document (quite possibly the most important step) a DIY rig, the person responsible for the system after you've moved on to bigger and better things might not have the desire or ability to maintain and inspect such a system. Quite often, when I do site surveys I find equipment abandoned because it is "broken."

Also, there is much to be said for the simplicity of Armstrong Motion Control. Motors and automation have a definite cool factor to them; however, you really need to assess whether or not the trade-offs of added complexity outweigh the benefits.

Finally, as Lambda pointed out, it may be worthwhile looking into how much it would cost to re-rig the existing hand lines to a more convenient operating position.