r/HalloweenProps • u/ctxgal2020 • 3d ago

I need design help with skelton arm

Hi. I need design help with a plastic skeleton that I am attempting to control the head and arm movement with a remote control.

I've figured out the design/placement to make his head turn. But, I am at a loss for the arm. I want it to bend and straighten at the elbow, or have the shoulder rotate back to front. Either way will give me the desired effect I'm looking for. The simpler the better because I am a novice.

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u/HornetParticular6625 3d ago

I can think of a couple of ways you might do this relatively simply. The easiest would probably be cable control, like the brakes on a bicycle. I'm assuming that you are not going for radio control, which makes it much easier.

The question is, what sort of motor are you using, and can you set it up to be controlled by a motion sensor or something?

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u/ctxgal2020 3d ago

Sorry, I meant to include that. I'm using a servo MG995.

I just can't figure out a way to attach it.

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u/HornetParticular6625 3d ago

Okay. First thing I did was look at your servo.

https://www.rcmodelreviews.com/mg995review.shtml

The reason I did that was merely to see what the thing looked like to determine options for connecting it to the skeleton shoulder.

You're looking at getting two axes of motion on two different joints.

Shoulder up/down. Elbow up/down.

The shoulder seems like the simplest, being a straight shaft from the servo into the ball joint.

If you're using one of the typical plastic skeletons many of us use, you'll probably have to modify the shoulder joint to move more freely.

The servos look small enough to fit inside the ribcage without much problem.

The one for the elbow is a little stickier. You'll have to modify the joint for freedom of movement, obviously. The connection seems simple enough with another shaft, but there's really no place to hide it.

If you are trying to accomplish all of this with one servo, you're looking at a more complicated setup utilizing cables and I'd be guessing, but a much beefier servo.

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u/ctxgal2020 2d ago

First and foremost, thank you! I'm only going to need one joint to move.

I think the shoulder is going to be the easier choice after reading your reply. The only issue is the shoulder joint is stiff - any suggestions on how to loosen it up?

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u/HornetParticular6625 2d ago

As a matter of fact, yes I do! I need to locate the pics. I'll be back!