[keithcorcoran]

I'm building some ghouls in the style of Pumpkinrot's Tin Man shown in the image below and I'm trying to devise a way to animate the arms to create a swinging motion.

The plan is to have a pick in the ghoul's hand digging a grave.

I want the arms to raise slowly or at a normal speed but then fall forward under their own weight so the pick strikes, or appears to strike, the ground.

Though this could be done with a cam/follower mechanism but I'd like to keep the mechanics within the upper torso if at all possible.

Next I thought of some sort of linkage with an actuator on a wiper motor that pulls the linkage attached to the shoulder downwards thus pulling the arms up. Once the rotor spins past a point it releases the linkage and drops the arms to the starting point.

Needs to be continuously running, electric, no pneumatics.

Seems like this would be the most compact and doable with a wiper motor.

Any ideas would be appreciated.

Creature reference courtesy Pumpkinrot...

 

[DaveintheGrave]

Two years ago I built an animated window silhouette that makes a movement similar to what you are describing. I don't know how much room you have to work with, but maybe this will spark some ideas/solutions.

http://smg.photobucket.com/user/DaveNTracy/media/Window Silhouette/006.mp4.html

http://smg.photobucket.com/user/DaveNTracy/media/Window Silhouette/007.mp4.html

 

[Raven's Hollow Cemetery]

Where I'd go with that is a pair of 2 bar linkages for the arms, similar to what HeresJohnny did with his Phantom Shadow ghost for the elbow movement. Although, obviously oriented front to back instead of side to side. It's not as compact of course, but there's not many other options that don't require quite a bit more space.

Couple that with Dave's awesome silhouette mechanics for the chopping motion and...


Plus, Rot is the Pumpkin King. *swoons* My hero.

 

[keithcorcoran]

That's exactly the idea I describe in my first concept. I just wasn't sure if that would work.


Here's what I sketched up before the sketch you see above and it's along the same lines as what you built.



Now that i see an actual mechanism, I might be able to translate small circular motion to the larger sweep necessary.

So I still have a plan A and B.. cool.

BTW.. your prop idea is GREAT.. lol. I would keep that in my window all year. haha.

 

[keithcorcoran]

the motion on this phantom shadw ghost is SO cool. I love the 'complexity' of the linkages and the cam/follwoer setup. Nothing like some old-school automata!

 

[DaveintheGrave]

BTW.. your prop idea is GREAT.. lol. I would keep that in my window all year. haha.

Thanks a lot! Well, the neighbors might not be happy if I did that.