Thread: chukie doll wiper motor help

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hey everyone! my ext prop was going to be a 4 foot chuckie doll using a chuckie costume from halloween asylum (it was on sale for 8.00) that raises and lowers a knife and holds a severed head in the other one i wanted to know if anyones seen a design template for this how to connect the wiper motor to make his arm raise im trying to make up a desing on how to place it but i dont want to put it all up and find out it doesnt work so i was gonna modify it off another video or template! or has anyone made an arm lower up and down and would know how to construct this!

Thanks,
Chris

Some questions you need to answer.

How long is his arm?
How big a stroke of the knife do you want?

If you want the arm to move rapidly, then the wiper motor should give you the speed you want. The critical part will be the mechanism itself. If you wish to create the movement at the shoulder, your arm will need to be strong and light. You can use a spring to keep the arm raised and then a cable connected just above the elbow to pull the arm down. If you try to direct connect the wiper motor to the arm and have it raise an lower the arm, you may have some inertia issues to deal with. The big question here is how rapid and violent do you wish the stabbing motion to occur. The more rapid and violent the movement, the more robust your design will need to be. You might even need some form of dampener at some point.

Originally Posted by spinman1949

Some questions you need to answer.

How long is his arm?
How big a stroke of the knife do you want?

If you want the arm to move rapidly, then the wiper motor should give you the speed you want. The critical part will be the mechanism itself. If you wish to create the movement at the shoulder, your arm will need to be strong and light. You can use a spring to keep the arm raised and then a cable connected just above the elbow to pull the arm down. If you try to direct connect the wiper motor to the arm and have it raise an lower the arm, you may have some inertia issues to deal with. The big question here is how rapid and violent do you wish the stabbing motion to occur. The more rapid and violent the movement, the more robust your design will need to be. You might even need some form of dampener at some point.

I think im going to have to try my mechanism wth the wiper motor i dont know the power it will give me yet but i am concerned to see!

A wiper motor will give you plenty of torque. Look here or do a forum search for "simple arm animation" to find my post on a simple up and down arm motion.

Simple Arm Animation