Help with arm design please.

Hello ,
 It's been a long time I have a question.  I working on a prop  the is a puppet and  I would like to figure out an arm mech that would give me the best range of motion. I figure I could use a pan and tilt for the for the first joint of the shoulder , SO I have up down front and back, but after that where the elbow would be i get lost should i do a cable like mech  and down to the wrist do the same. I believe the org. was done with rods and a waldo but I was going to use  an arduino  so i can pre program it on a timer . this is just for personal use so crude is fine. I never seen something  like i'm talking about being sone before.  Thanks for any info.




  • Hi Gary,

    Cable mechs are great, since you can then put any servos in the body.  That way the servos are just moving the weight of the arm, and not the weight of the arm and all the other servos/mounts/wires/etc.

    One thing to keep in mind about shoulder joints is that the arm not only moves forward/backward/out, but also rotates.

  • Steve KociSteve Koci ✭✭
    edited January 2017
    I use the Actobotics gearboxes from ServoCity.  You can see  "under the covers" of one of my characters at
  • Those arm-movements look really good! I'd love to see some close-ups of the mech!

  • This is a different project but should help.

  • Very nice! How do the servos hold up?
  • They hold up great!  Paired with the 7:1 gear sets, they have an incredible amount of torque.  I overbuild to be sure I have power to spare.
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