Conveyor Belt in raised deck

Hi everyone,

Working on a production of Footloose and we want to have a conveyor belt system spanning 40' across our stage to move actors and small set pieces onstage/offstage, and across the stage. I have never built/worked a conveyor belt into a stage deck before, any help would be great! We want it to move forward/backward and have speed adjustment as well. Also - can these types of things be DMX controlled? It'd be awesome to build it into a cue =]

Thanks!

 

Automation Direct sells many of the parts that could be used for this and if you call them have application specialists that could help you with the details. It's not the most reliable or highest quality equipment, but it does work and the price is certainly right. Speed control shouldn't be a complicated add on.

As far as controls go, DMX relays could trigger motion and/or direction. You would need a person dedicated to monitoring the safety of the piece's motion though. Normally this is someone that holds a deadman down to allow motion to happen. That person could be onstage or in the booth, but this needs to be their only job during motion so that they have no distractions.

 

Thank you! I had planned on one single stagehand being dedicated to it, and in fact it will most likely be me installing and running. With this being larger than 40', is there any issues on weight or structural support that you would know of off hand?

 

Industrial automation systems can move tons of load at intimidatingly fast speeds. It's all a matter of money. A conveyor system can certainly work but there are certainly some design considerations that make it a less cost efficient option when compared to other ways to move things onstage.

Footer is right though, unless you really want to see the conveyor belt (a la Kinky Boots) then the standard stage gag is to use dogs in a track with wagons. The same considerations go into that as do a conveyor system anything is possible the price just goes up with the capabilities.

 

Whenever automation is in use, you also need to have redundant limits built in (software stops, hard stops, and emergency stops) in addition to the enable/deadman switches. I'm not aware of anyone using DMX for automation controls, but then again, I'm not an authority by any stretch of the imagination. So there's my 2 cents. Yay.

 

Can you just imagine how some newb's going to misconstrue: "dogs in a track with wagons"
Toodleoo!
Ron Hebbard

 

It seems this is either to move things on and off stage, a wagon, or if you want that walking/running in place, with moving background, or along with everything moving in one direction. One is not so hard, the other more of a challenge.

 

Do you need to just move scenery onstage or do you want the "walk in place" look with actors?

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Don't want to rain on your parade, but conveyors that can handle dynamic loads are difficult and expensive to do. Your standard factory belt has a constant load of parts/materials evenly distributed across its length. Having people walking and jumping on it adds many different stresses to the system and makes keeping a constant speed difficult. We just did an automated conveyor gag for big client and spent in the 10s of thousands outsourcing a company to build the control system for us. And this was for three 8' long conveyors. I can't imagine the price of a 40' long belt...

 

I certainly can see how a project like that could easily be that expensive, but there is a huge range of what's available out there. You may have provided a very nice system with a very tight feedback loop that performed exceptionally well and was entirely worth the pile of money the customer paid for it, but that doesn't mean that kind of control is necessary for every gag. Light to medium capacity, low speed, while using the feedback loop internal to the drive could make the control side pretty reasonable (by reasonable I'm talking in the $2k-3k range). That doesn't include the construction of the belt and bearing system itself which is not exactly cheap but wouldn't necessarily be crazy either.

You could drive a stage lift with a hamster wheel if you got the right gear ratio, it just would go very fast and would have a gratuitous amount of backlash... and you'd have to remember to feed the hamster.

 

Not to beat a dead horse, but being that DMX control was brought up I wanted to chime in

DMX is "open loop", meaning that it is not continuously polling. In industrial automation systems, a PLC "closed loop" architecture is much preferable for any type of system in which people are involved. This allows for safety features such as true "hold to run" motion. That is not to say that it isn't possible to construct a safe DMX control system (with the right amount of additional interlocks and checks), however I know of no automation equipment manufacturer that does so - or at least a major one that is well received by the ASTC. This actually recently came up on a mailing list that I subscribe to.

We were once asked to operate our HMI control station via remote DMX for a non-life-safety automated rigging effect. We were able to get it done by "pulsing" check values to determine whether or not the UP or DOWN button was being pressed. It worked, but it was clunky and there would occasionally be a delay between releasing the button and the equipment stopping (and vice versa). We required that they install additional hardwired E-Stops, which they weren't happy about... I apologized, but I did my best to talk them out of it in the first place.

I also would recommend CreativeConners on this one, though I fear that it may be cost prohibitive. That isn't a knock on them at all - these types of systems become extremely complex (read: expensive) very quickly. You never know, though. Pretty smart outfit over there.

 

Hi all,

A few clarifying answers to these comments.
1) The effect we want is to have a movement of people floating out on to stage continuously. IE, the actor floats on Stage Right, steps off center and does their bit (meanwhile the belt is still running), returns up onto the treadmill and floats off SL (either walking or standing still). As that person floats off SL, a new actor appears on SR and repeats the prior actions. ** we want the speed of this to be a max probably 3mph.
2) We potentially would want to place small accessories or tables, etc onto the treadmill to enter/exit them seamlessly.
3) I obtained a copy of Mechanical Design for the Stage to get a better understanding of the physics/math required for this effect. The formulas in the book are for a 20' x 3' treadmill and states the top part of the loop should rest on UHMW polyethylene to reduce friction, supported by 3/4" ply and framing for structural support. I assume this is standard practice?
4) I have looked at CreativeConners and noticed they do have a 40' unit. We are going to look into pricing and possibility, but are concerned because they are West coast and we are East.
5) As far as DMX control, I understand thats not really a thing so we won't go that route now. I have no idea how any of the control for this would even work. Something I guess I'll have to look into more.

We are planning on tracking wagons further upstage and this Mechanical Design for the Stage explains how to do so, however I am not sure if we will get that same effect I explained in #1 with a tracking wagon...

 

I don't know a ton about automation, but I know of people who have used Creative Connors and loved them and their gear. They are actually in Warren, RI. Rather than a conveyer belt, I imagine it would probably be easier to use small "palettes", or moving platforms that track on and offstage (it sounds like two for your effect, each tracking from one side of the stage to center), rather than a conveyor belt. When offstage, they could be preset with those set pieces, or without to allow the actors to move onstage without walking.

 

Sounds like you might be able to build portions to reduce some of the cost, but you should call Creative Conners. They work on a wide variety of effects nation wide and will be able to help you design a safe, repeatable system.

 

Your description is very clear. The belt approach, like a treadmill, seems correct but not sure how to calculate friction, etc. I could see "slats" on two roller chains, but lots of forces to calculate and design for.

Consider a race track where instead of rollers with walk surface returning under the top, a series of wagons - say 3x3 or 4x4 - driven by a roller chain (maybe wire rope?) along one edge, and it pivots 180 degrees in wings. Yes, you need wing space and you have these varying triangular gaps as the wagon rotates 180 degrees, but seems feasible. Lots of details still.