Help needed- rotating drum riser

Jeff Williams

Jeff Williams

Sophomore
Jan 18, 2011
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Tulsa, OK
bluebabysound.com
In addition to running sound I have a cheesy cover band that I play with a few times a month. We are over-the-top cheese rock covers and I want to make it extra cheesy by adding a rotating drum riser. (I'm looking to build a "poor band's" rotating drum riser.)

I have 3 issues that I haven't overcome in my design.

First: Suggestions for cable management so they don't get torn to shreds.
Second: How to make it default stop facing forward.
Third: How to change rotation direction???? (thinking of a simple stomp switch to reverse A/C)

I plan on building a frame from square tubing with a motor attached. The plan was to be able to control the rotation thru our light show (showxpress) by activating a motor via a dmx switch pack.

I'm open to other ideas as well.

Anything thoughts to contribute to a extra cheesy band?? :-)

New Band Promo Video:
http://www.youtube.com/watch?v=Iz6QL77aRaA&feature=g-upl&context=G2e61e70AUAAAAAAAAAA
Audio recorded live with a studiolive 24.4.2 and doctored with studio 1.
Video was a freebie from a webcast jukezoo.com was doing.
 
Re: Help needed- rotating drum riser

Only 3-phase motors can be easily reversed with a simple switch. Single phase motors have to be wound for it, or you need a transmission.

I'd actually recommend a 3-phase or DC motor with an industrial variable-speed drive. You can probably pick one of these up pretty cheaply on eBay, and you wouldn't have to worry about gear reduction so much since motors on such drives are pretty much constant-torque at any RPM.

I think a roller switch with a detent welded to the frame could stop the motor at the center position.

You're going to need a big bearing or something for it to rotate on, maybe you could make one with some channel and a bunch of ball bearings?

If you're going to go that far, it needs to be able to rotate infinitely, so you are probably going to need to get a lot of wireless channels :)

I just don't know how you're going to implement control - is this something that will happen in specific songs, is it completely random, how will it be used?
 
Re: Help needed- rotating drum riser

Thanks! Good ideas for the motor & frame!!

It would only be used a couple of times during the night for "WOW" factor. My thought was to plug the motor into a dmx switch pack to control the duration of power to it.

Luckily my dad is a retired engineer (with several welders) and looking for a project to waste time on. I'm hoping to use this project to improve my welding skills.
 
Re: Help needed- rotating drum riser

since you're the drummer in question, you might be able to simplify control by simply triggering it locally yourself with a foot switch. i'd also strongly recommend some kind of local kill switch regardless of how you control you it to give you the ability to stop it should you need to...

cable management is pretty easy if you stay in the 'less than 360 degrees' realm. center hole for everything to go into. strain relieve it at the rotating portion and the fixed portion below with enough slack between to twist a bit...

if you want to go much past 360 degrees, it gets more dicey...
 
Re: Help needed- rotating drum riser

Some thoughts, in no particular order:

A standard theatrical approach to turntables is to build a full base enclosing the turntable, and use casters wheel up to support the turntable. This greatly reduces the load on the central bearing, and allows it to be simply a positioning fixture. Drive is often either some variant on belt drive, and need not be motorized, or a pneumatic tire driving the edge of the turntable. Getting the turntable to index properly with a varying load (and probably dynamic movement on top) is a harder problem than you think, and you'll probably want to either live with the turntable never stopping in the same place each time, build in some hard stops to the rotation, or implement a real control loop.

If you limit the rotation, you can get away with simply looping your snake under the turntable. You can probably get away with ~360 degrees of rotation, but no more. For more rotation, you'll need another approach (wireless or Whirlwind's E-snake have both been used). Don't forget to fasten down your drum kit and mics - they may not stay where they were put when you start to move.
 
Re: Help needed- rotating drum riser

Jeff Williams said:
It would only be used a couple of times during the night for "WOW" factor. My thought was to plug the motor into a dmx switch pack to control the duration of power to it.
Click to expand...

I would highly recommend dropping the idea of using DMX. Aside from the fact that it is a one-way protocol, it is built with "best-effort" hardware that often does not contain fault checking measures and a dimmer pack will not be happy driving a motor. Single phase AC motors cannot be reversed unless they contain a second winding, so that that limits you to three phase or DC. Personally, I think a DC motor with a drive would work well in this application.

As far as control, a PLC can be found cheaply on eBay and other places. Some of them are even life-safety certified with fault-checking hardware and can be made to do just about anything from running assembly lines at Ford to amusement park rides at Disneyland. Many have integration with motor drives since the same companies tend to make both. The two ways that are standard for this type of mechanism are an encoder and limit switch. A encoder counts the rotations from the motor and using a formula in the PLC, it can figure out where you are and how fast you are rotating. Then it can modify the speed and direction of the drive to put you in the "correct" position in real-time. A limit switch at the end of travel (or at a predefined location mark if it is a continuously rotating system) allows the PLC to correct accumulated errors in its counts.

To interlock the system, there should be an E-Stop on both the platform and the ground and a main keyswitch you can use to lock the system when you are away. I would also probably have a pressure switch wired into the seat of a mat underneath you so if you should move out of the "safe" zone then it will stop. To control it you could use a HMI (touchpanel), push buttons, Ethernet, serial, etc. depending on the PLC. There's all sorts of used industrial automation equipment on eBay these days. A great resource I have used for these questions is Mr. PLC. Sounds like it could be a really cool project.
 
Re: Help needed- rotating drum riser

When we did the Austin Rodeo years ago they used a stage that rotated 7 times in one direction and then rotated back to the start position. We coiled the snake under the stage with enough twist so it would uncoil 7 times and then coil back up. Worked fine. The hard part will be how to deal with the snake coming up right in the middle of the riser, and still place you drum on there without interference.

I know that Ezra Charles (actual name is Charlie Helpinstill, the inventor of the piano pickup) did this and placed himself and a 5 foot grand piano on the riser. He had a foot switch with simple forward and back controls. No limit switches or anything, he just stopped it when he wanted too.
 
Re: Help needed- rotating drum riser

Silas Pradetto said:
If you're going to go that far, it needs to be able to rotate infinitely, so you are probably going to need to get a lot of wireless channels :)
Click to expand...

Dave Rat has blogged about a rotating drum cage. I think they went for 2,5 rotations max and allowed enough cable to accomodate that by running it through the "hub" of the centre bearing.

They also ran wireless backup which they didn't need on the end.

Military machinery like tanks have sliding contacts for turret coms, control, etc, etc which allows infinite rotations. Costs a fortune!
 
Re: Help needed- rotating drum riser

Great insights and links. Thank you guys!

<sarcasm>I think I'll do a replica of the Blink 182 riser, it seems to be the most cost effective route to go.</sarcasm>

I'll post pics when we get this project going. I'm sure I'll have more hurdles to overcome as well :-)
 
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