# 3 foot talking skull



## Shock (Apr 14, 2012)

I posted in another post but figured this would be more clear.

I am making a giant 3 foot tall by 2 foot wide talking skull and need a super servo to control the mouth movement which weighs an estimated 1 to 2 lbs.
I have read a lot about using a wiper motor in a servo configuration to achieve this effect. Does anyone have any schematics or wiring diagrams, thoughts, ideas, links, etc.

Thanks,


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## HomeyDaClown (Oct 3, 2009)

There are a lot of articles on the web on building monster servos out of wiper motors. http://www.rcuniverse.com/forum/m_9236698/anchors_9236698/mpage_1/key_/anchor/tm.htm#9236698

It's not too difficult to setup but you will not have a lot of speed with any wiper motor in terms of degrees rotation per second. It would be fine for basic movements but hard to get the wiper motor to respond quick enough to realistically move the jaw.

For a setup like you want to do, I'd use two way pneumatic cylinders instead. Plenty of speed there and you can still control it from a PC running VSA ($$$) or Vixen (free) with a basic relay board.


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## Shock (Apr 14, 2012)

Thank you for the info.


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## spinman1949 (Jun 29, 2009)

Another option is to stay with the servo and counter weight the jaw. I did this with my 3 axis and it allowed me to use a sub servo. If you can mount the jaw on a shaft you can use a spring and collet to allow for easy adjustment. I basicall got my jaw to stay closed with the spring and then the servo just had to overcome that force. Naturally you will still need a fairly strong servo to deal with the inertia. Here is a servo that while not cheap, would likely handle the load. It is fairly fast as well which you need for good mouth movement.

http://servocity.com/html/hs-7980th_servo.html


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