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Automaton mechanics




A cam changes the input motion, which is usually rotary, to a reciprocating motion of the follower. Cams can be shaped to change the way the follower moves. The shape of the cam is called the profile.

So, in the image below, if the cam rotates clockwise, the movement of the follower in 1 would be a gradual rise and fall motion for each rotation; the follower in 2 would rise and fall twice for each rotation; in 3, the follower would be motionless for half the cycle and then rise and fall; and the follower in 4 would rise gradually and then fall suddenly. Note that 1, 2 and 3 would have the same result if the cam was rotating anticlockwise; 3 would jam. Thes aren't the only shapes you can use. Anything goes...depending on what sort of motion you want...though there are practical limitations to making these things out of wood.



Other sorts of cams are the box cam (below) which consists of a rotating disc with a groove is cut/milled into its surface (this is the profile). The groove may be an unusual shape as seen in the example below. As the disc rotates the follower follows the path of the groove.

box cam

The diagram below shows a basic example of a flat plate cam/linear cam. As the flat plate cam profile moves to the left the follower moves up and down, matching the shape of the profile. The flat plate cam then reverses in the opposite direction and the follower drops and rises again.

flat plate cam

As the cylinder cam profile rotates the follower moves upwards. When the follower reaches the top, the cylinder cam rotates in the opposite direction and follower moves back down.




More coming soon!!

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