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Discussion Starter #1 (Edited)
Hi guys and gals

So I am working on my drinking pirate, in this case he moves his arm with a jug up and down to his face. I have constructed the body already out of ½" PVC (nothing glued yet). I have not yet worked on the motor/mechanics because I suck at that part. I made a sketch as below that shows how he's built at the moment. The motor attachment to the torso was the best I could think of (marked in red). A spinning plate with a link that manipulates the arm.
I don't think it is very elegant though, and maybe it could cause tangling with his clothes?

I have a 5 rpm 12VDC motor for the task. I am just not very confident in my mechanical skills. I have looked at the robives.com page but unfortunately my brain won't play.

Could anyone help me out with a sketch?

creepy2.jpg
 

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I would try and move the whole arm by the shoulder or elbow rather than use a rod to the wrist /hand.

you might try something like a brake cable from a bicycle running from the motor, down the bicept area and attach to the forearm. then just the elbow would move.
 

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I am posting on my phone so cant really draw a picture, I can later when I get to my office.

but the idea is you make the joint (elbow or shoulder) a hinge so it can go back and forth. then, you attach the cable (doesnt have to be a cable, could be a thin rod or stiff wire) to the part you want to move, you pull or push the cable/rod to make the forearm move.

The advantage to a bike cable is you could put the motor anywhere, with a rod you would have to put the motor in the shoulder area to move the forearm. or between the shoulder blades to move the shoulder.

edit, a really bad phone sketch

Sketch183123636.jpg
 

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I think untillater has hit on the better idea... in fact, we did something very similar with our robot skeleton, Mr. Bones. In our case we used a cable to rotate his entire shoulder to raise his whole arm, using a wiper motor as our muscle. If you wanted to keep all the mechanical parts out of the way, you could even mount the motor in the body, which is what we did, then run the cable over small pulleys down the arm. The push rod coming out the middle is a more direct approach, but will definitely interfere with clothing, etc. Check out this video:
Watch around 2:29 and onward. it'll give you an idea of how we cabled up his arm. You could do something similar for just the lower part of the arm.
 

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Wow! ˆThat's very cool!

You can also take a look at heresjohnny's blog. He gets an amazing amount of movement out of a motor, and uses a lot of cable and eye hooks.
http://johnnysghost.blogspot.ca

I don't think he has anything that matches this movement exactly but it's a great site for inspiration.
 
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