[Creepytina]

Hi everyone,
Earlier this year I got interested in learning how to use basic servo motors to do simple animations, but figured I would wait until after Halloween and do it for next year's haunt... But now I am itching to do something with one of my new props this year. I have two large dolls (CVS's 9.99 "wispy-walker" dolls) that I have dressed all in white, going to pose them (and a third in the middle) as if they are jumping rope, like from nightmare on elm street. Maybe have the 1,2 Freddy's coming for you song playing on a loop near them.
So now I really want to make the jump rope spin. I was going to shape a covered wire to be the rope. Anyone have ideas on how to do this? Could I mount one motor into the chest of one doll, run the wire straight through a washer or something in her hand, then attach the other end to a swivel by the other doll's hand?... It would even be cool just to have the spinning rope and song with NO dolls, now that I think of it...
Any ideas appreciated. They are creepy enough with no motion, but I do need to spread my wings a little.

 

[Bruzilla]

Wow... that would be tricky.

I would think you will need two motors. That wire isn't going to be very rigid, so no matter how easily the far side can rotate, the side with the motor is going to generate enough torque that it'll likely push that end ahead of the far end, so the rope will twist. Having motors on both sides should balance out the torque.

I would mount the motors on poles and have them hidden behind the dolls. That way the arms can rotate from their sides, which will look more realistic.

Now, getting the arms to rotate about the rope... that's gonna take some thinking.

 

[chaosandhavok]

An option would be to run a wire through the rope and make it rigid. Then bend the wire into the shape of a jump rope at the time of spinning.

 

[Michael Smith]

How do you intend to get the rope under/around the doll in the middle?

 

[Bruzilla]

If the "rope" was being turned using a wheel, then a smaller wheel with a rod coming from it could be attached inside the diameter of the rope. Attach the rod to the third doll and have it lift her up and down.