Thread: Vibrating platform

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I am planning an electric chair execution theme for one room of this year's haunted house. I like to throw in a little surprise with my scenes so I would like the "witnesses" to the execution to stand on a low platform that would vibrate at a fairly high frequency as the victim is fried.
I have considered mounting some sort of power tool such as a jig saw or concrete vibrator to the underside of the platform to create the effect but I was wondering if anyone knew of an effective and inexpensive (not to mention safe) way of accomplishing this.
I am not that familiar with pneumatics so a mechanical solution would probably work best for me.

Thanks!

Pneumatics is a non starter, this needs to be an electric motor.

Vibrations are caused by an out of balance motor, however, the mass of the object you re trying to vibrate is very much a factor when it comes to vibration, and in the case you quote your mass may be 6 people, making maybe 1,000lbs... that's a lot of mass to vibrate.

The other factors to take into account are the speed of the motor and the mass of the out of balance mass.... the greater the better.

I would say that a washing machine motor is what you need here, bolt it to the underside of your platform and then add a flywheel with the shaft hole about 1"-2" off centre.

Another factor to take into account is the frequency of the vibration, this is the actual speed of the motor, you may find that you need to add a speed controller or gear the motor up or down... getting the frequency right is the first thing to do, then increase the out of balance mass to get the amplitude of the vibration right.

Remember that the amplitude is a ratio of the out of balance mass and the mass you want to vibrate, this means if your basic platform is light... say 50lbs then the performance you get with a 100lb (ie 150lb mass) child is very different to that of a 1000lb party (ie 1050lb mass)..... which is 10x the child... if you make the platform 1000lbs then the child scenario is 1100lbs and the party scenario is 2000lbs... but more importantly only twice the mass of the single child

Thanks for the idea. I had considered using an off-balance motor but my only concern was in how long it would take to get up to speed. I want the effect to be immediate and more like an electrical charge than a rumbling. I would think the motor would create more of an earthquake effect. (Which may be an idea worth developing in itself!)

Originally Posted by GntlmnJac

Thanks for the idea. I had considered using an off-balance motor but my only concern was in how long it would take to get up to speed. I want the effect to be immediate and more like an electrical charge than a rumbling. I would think the motor would create more of an earthquake effect. (Which may be an idea worth developing in itself!)

Tuning this is not easy, vibrations are very much a science in there self

Are you familiar with the old centrifugal governors that you see on old style machinery?..... it looks like a pair of spinning balls (cos that's what it is), well there is a vibrator you can build that is like thin but with only one ball..., the advantage of this design is that you can start with the load in balance and thereby only cause minimal vibration, but as the motor increases in speed the ball spins out creating a larger out of balance mass and increasing the vibration amplitude.

Sounds interesting. Do you have a link on how to build one?

here is a link for a flyball governor

Modeling the Environment: An ... - Google Book Search

Note that it has two balls opposite each other to maintain balance, and eliminate vibration, however, if you remove one ball and all a spring to reduce the speed at which the ball fly out then you have a mechanism that start out in near balance which helps it get to speed quickly, yet as it gets to speed the out of balance force will overcome the spring and cause the ball to fly out, increasing the out of ballance mass and therefore increasing the vibration


NOTE SCREW THIS UP AND THE MECHANISM COULD DISINTEGRATE, and spray shrapnel over your visitors, make sure there is at least 1" of timber or a steel plate between the vibrator and your guests, and there is no opportunity for ricochet......THIS DEVICE CAN KILL!

Buy 50 old used vibrating sanders and bolt them all to the bottom of your platform. Make sure you have a circuit capable of running all of them at once and throw the switch.

The vibration should be instant and should give you that "Buzzing" electrical feeling you are looking for. In fact, the sound it makes should enhance your display.

OK, maybe 50 is an exageration. Try 5 and see what it feels like. It should be enough to give you that buzzing feeling in your feet no matter how many people are standing on the platform. Just make sure you have a vibrating sander for every couple of square feet of the platform.

That's my low-tech solution.

Get them at yard sales or on ebay:
vibrating sander, Construction, Tools Home Improvement items on eBay.com

We used a washing machine motor 2 years ago, to vibrate a floor when about 5 people would walk over a ramp..... work pretty well. I think more thant the effect of the vibration, was the NOISE it made when the Out of Balance motor started ! We had to 'wedge the ramp so that is didn't WALK all over the floor..... by the end of the 4th night, the vibration had worked the wires loose so the motor quit. So if you use this method, be sure to secure your floor in a way that is doesnt WALK, and be sure the wires to your motor are VERY secure.

I've had a similar idea in my head/plans for several years. What I wanted was an interactive prop and have a "volunteer" sit in the chair and some one throw the switch causing the chair to vibrate.

I experiement with a couple of items but never got the desired results, I was looking for something that you could feel right a way lets say a very strong vibration.

I picked up a couple of vibrating motors that were used in a "magic" fingers bed. You could feel a vibration but it was not real stong. Next I tryed a pneumatic vibrator, it was a turbine type which are not as loud at the ball or pistion. However it was not big enough. I think the pneumatic would work if it was a large size but they are very expensive (even on ebay) and require a large volumn of air. here is one manufacture VIBCO Vibrators - Your one source for high quality industrial vibrators, concrete vibrators, dumpbody vibrators, and other vibratory material flow aids. From concrete vibrators to dump body vibrators to bin and hopper vibrators, VIBCO has over 1,300 .

I've even looked at one of those paint shakers they used for the large 5 gallon buckets, again very expensive even for the used ones.

I like the idea of the washing machine motor and off balance weight thats basically what the bed vibrator motors were but the washing machine motor is a much larger machine. My only concern was getting it too far out of balance and having it self destruct.

Also I think you need to isolate the chair or platform from the ground on some springs or rubber mounts. This way your shaking only the platform and not trying to shake the front yard.

There's a lot of creative members on here so a good ideal will come up. Keeps an eye on the thread. Best of luck

I found instructions for doing that last year but the link no longer works for me Maybe you will have better luck Look on this page there is a video of the vibrating bench in action. HauntProject.com - Your visual source for Haunting How-To's