Building of the rotational wrist part.

After printing you should have five parts.
Remove with pliers the support. Fix in the bracket the servo MG995. Use the Arduino to set it to 0 degree.
Use one of your spare actuator from your servo. Cut it and fix it to the small gear as shown. It shouldn’t be oversized.
Grease the big gear before setting in “rotawrist2”.
Drill and tight fit the gear to “rotawrist3” through “rotawrist2”.
Use hot glue gun to position and fix “cableholderwrist1” to the top of the servo. This will help to guide the rods into the center hole.
Close the whole thing and tight the 3 screws on perimeter. Make a test run with your Aduino. This is the position you should have when your servo is at 180° for the left hand
Now it’s time to glue “rotawrist1” to “robpart2V2”. Once glued detach “rotawrist1” from “rotawrist2”. Start running the rods from your servos up to each finger. (Use the Arduino to set your servos at 0 Degrees) Don’t twist the rods and make sure the upper rods run through the upper parts of the fingers, run the lower rods through the lower parts of the fingers.
This is where you are going to test your patience and skills. I use twisers for to do the job.

Comments 3

  1. Where I have to connect my rotawrist servo?
    Has it an electronic card or just connected in the arduino 1 with the others 5 servos?
    And he need to another personal flex sensor ?
    I don’t find any informations in the website about this.

    Thanks before all.

  2. Hello All,

    First of all, I am a new builder & I am working on my first arm after I completed the finger starter. It is very exciting to work on this fantastic project that Gael has made available to us!

    I am not sure if this tutorial is the right one to ask but; I cannot work out how to get the small gear to fit onto the wrist servo. The hole in the one that is supposed to directly mounted onto the servo is far too small to fit and drilling it out would make it lose it’s teeth to grip the servo. Mounting the other small gear on a cut off original servo arm is also not possible because there is no way you can get the screws into the printed gear (the gear is too small). I have tried doing it on an angle, but that does not work either

    How have others managed to do this?

    Dumb “newbie” suggestion; could the small gear not be made a little bigger and the larger one a little smaller and all would be good? I understand the gear ratio would be different but the way it is now appears to be very complicated and frustrating

    Thanks for any and all help you can give me 🙂


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