Thread: rotating (swaying) torso mechanism?

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Trying to reverse engineer (mentally) the swaying motion of a Creepy Cathy type swaying zombie prop.

This seems like a simple movement but I just can't think of a mechanism that wouldn't require a lot of torque or put a lot of load on a wiper motor (increasing the amps needed to run it)

here are a couple of examples of the motion I'm looking to acheive.. preferable in a prop with pants (so the mechanism would need to fit in the pelvic area or within the torso making all the internals sway with the prop)

Creepy Cathy


Combover (this is more the type I plan to build and speed I want to run it)



I saw a project for a swaying gypsy but I'd like to do something with a wiper motor and linkage on a PVC prop.

I built my own version of Creepy Cathy this year using a wiper motor and the exorcist girl prop that you can get just about anywhere. I stole the audio from the very one you are talking about.


Tonight I will take some photos of her internals and post them.
It is really very easy to do with a wiper motor.

perfect. thanks.

I just finished my wiper motor rocking chair (granny rocking chair rip off) and this one seemed like it would be easier but the concept escapes me for some reason.

any luck with that photo?

thanks.

Hey Hauntcrazy, I too am looking forward to the details on the mechanism.

Thanks

The cool thing about the creepy cathy prop is her sway is intermittent giving her that jittery motion. She doesn't keep rotating constantly like a zombiette would. This is achieved with a very inexpense programmable / random-motion relay from Cebek. The creepy cathy mechanism is extremely simple, as well. Just a wiper motor attached to a slightly bent shaft, with the straight part of the shaft attached to the motor and going through a grease ball-bearing collar, then the bent part of the shaft is inserted into a straight pipe molded inside the upper torso. The upper torso is attached to the lower torso by foam-filled latex "cushions" on each side (with the mechanism / motor area hollow) which keeps her facing forward, but gives her the flexibility to bend. The only thing that turns is the bent shaft. I'll post some pics of her actual mechanism if anyone is interested.

Originally Posted by craigsrobotics

I'll post some pics of her actual mechanism if anyone is interested.

Sure, thanks!

would definately be interested in a photo.

i thought about a bent shaft direct drive but was concerned about the amperage I'd need to turn the whole upper body and thought there might be some sort of reduction mechanism to minimize motor load.

right now I'm using these power supplies because they're readily available for me. (read: free)
15A @ 5v
3A @ 12v

the pot adjusts the voltage (motor speed)

these are primarily used for oldschool arcade machines

If I'm reading your post right, I would be concerned about reducing voltage to the motor to control speed. I use this controller



http://store.qkits.com/moreinfo.cfm/MX033 which uses PWM technology to reduce speed without cutting the torque of the motor. I get full motor torque at any speed. It will handle 12V or 24V and up to 15 amps. $19.
It will also fit nicely inside an ATX power supply.

I should think that a wiper motor would be more than strong enough to handle this prop, as long as you can get power to it. Then it's just a matter of controlling the speed.

from what I've read is that people are running thier motors with lower voltages to get slower speeds.

i could be totally wrong though... i was just happy to find a power supply in my garage that actually turned the damn motor after going through about 8 12v wall warts.

I didn't even rememeber about using an ATX PS. I gave away about 10 of them with a bunch of computer scrap I let someone have a couple of months ago.

time to start dumpster diving for next year.