# Razor Pendulum



## Shock (Apr 14, 2012)

I want to make an automated razor pendulum like can be seen in this video and many movies. check out Halloween Horror Nights Universal Studios.....
Specifically at mark 1:09.............




Question:
What mechanisms can be used to make the pendulum swing?
My thought would be a motor with an arm attached to the pendulum, like an FCG. Maybe a motor driven by a servo with limit switches and relays.

What types of ideas can you come up with?


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## Shock (Apr 14, 2012)

Typo....meant to say @ mark :09


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## DarkLore (Jan 25, 2009)

My first thought would be a wiper motor. But I would also consider electro- magnetic. As the pendulum swings past center, a sensor could trigger a magnetic field to pull the pendulum across and immediately turn off. The momentum would continue the upswing until it falls back down and the same thing happens in the other direction.


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## The Watcher (Sep 13, 2008)

I think a deer motor would run one fine. If you let the top of the pendulum run up past the pivot point. The motor wouldn't have much of a load. Then just run a bar from the pendulum to a arm on the deer motor. As it rotates it will swing it back and fourth like the motion of a tombstone popper. But it will be set up side ways. Where a Popper runs up and down.


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## VexFX (Sep 27, 2011)

The mechanism that powers the movement depends on the size of the swing you want, and the weight of the pendulum.

I've attached a simple diagram of how a basic linkage can turn the rotational force of a motor into a swinging pendulum. 

If you want a pendulum that retracts and then swings freely for a while before being retracted again, that would call for a slightly more complicated mechanism.


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## hpropman (Jul 27, 2008)

the mechanism that we used for the rocking granny prop would work for this. Look in this thread

http://www.hauntforum.com/showthread.php?t=20145&highlight=rocking+chair+granny&page=34


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