# Cam Help Needed



## tot13 (Jul 25, 2007)

I've checked a few sites but haven't been able to find what I'm looking for. I need a cam design to be used with a wiper motor that will move the arm about 90 degrees, return, and repeat.

To try to explain it another way, I want my Grim Reaper's arm to move from the elbow to the hand (he'll be holding a lantern) and move back and forth horizontally.

Any help with a cam design would be appreciated, as would any new websites.


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## Otaku (Dec 3, 2004)

Hmmm. Where will the pivot be located, at the elbow or the shoulder? You may be able to do this with a short crank arm on the motor.


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## tot13 (Jul 25, 2007)

Otaku said:


> Hmmm. Where will the pivot be located, at the elbow or the shoulder? You may be able to do this with a short crank arm on the motor.


I had intended to place the pivot in the elbow. However, that was merely a preference and I don't know if it would necessarily be the best way to do it. If it would be better to pivot from the shoulder, I'd gladly change my plans.


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## The Watcher (Sep 13, 2008)

You might could do this with a reindeer motor. The ones I have had are made to reverse when they get stressed. So I mount them on a board and set bolts where I want them to start and reverse. Here is a prop I made doing this with the head. There are 2 videos, you can see it better in the night one. Like Otaku said you could mount it in the elbow are shoulder.I actually mounted my motor to the pumpkin. The ran a steel bolt through the shaft. So the motor moved with the head. That way I got a small delay set in my turning motion. I also didn't need any linkage.

http://www.hauntforum.com/showthread.php?t=16250&highlight=daddy+jack


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## DarkLore (Jan 25, 2009)

I believe the best way to do the graveyard digger lantern, is to mount the arm fixed at a shoulder, to a horizonal that runs across the shoulders. Put a T into the horizonal, with a connection to the motor mounted in the lower torso. That keeps the motor stable and out of sight. The length of the arm off the wiper motor and the section coming off the T, will determine the amount of swing. (Sorry...no drawing tools on this PC to sketch it.)


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## DarkLore (Jan 25, 2009)

mymania shows what I was trying to describe in the thread called Grave Digger Animatronic Completed. Look at post #12.

Although I personally wouldn't use all pvc...that's the mechanics I was trying to describe.


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## The Watcher (Sep 13, 2008)

Oh I am sorry, I don't think a deer motor would lift it up and down. I thought you wanted to go from side to side.


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## RoxyBlue (Oct 6, 2008)

Tot, take a look at this web site:

http://www.flying-pig.co.uk/mechanisms/index.html

I don't know if it has the design you're looking for, but it explains movements and the mechanisms needed to get them really well with clear diagrams.

This set up gives a back and forth motion:

http://www.flying-pig.co.uk/mechanisms/pages/quickreturn.html


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## HauntNH (May 17, 2010)

I dont think you necessarily need a cam, maybe just offset the pivot point from the motor connection. check out scarryterry's page on the licking legs.

http://www.scary-terry.com/kicklegs/kicklegs.htm

I think you could use a similar principal


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## tot13 (Jul 25, 2007)

You folks are so awesome. Thanks so much for all the guidance and suggestions - you've given me a lot to think about, but I believe I'll be able to pull this off with the help I've gotten from all of you.

And Watcher, yes, his arm will move left to right (or vice-versa), that is, horizontally.
My intent is to have 4-6 of these in different poses, some automated, to light the path through my cemetary.


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