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CAM TOY EXERCISE

V. Ryan © 2006 - 2009

 

Below is a mechanical toy based on a CAM mechanism. As the handle on the eccentric cam is turned the top part of the egg shell lifts to reveal a face. The basic construction of the toy is also shown below. The ‘flat’ follower moves upwards and downwards as the cam rotates. Although the design is simple it must be made accurately or the mechanism will stick. (Look at common faults sheet).

   

 

 

Two similar examples are shown below. However, each one has a different cam profile.

 

A ‘drop cam’ has been used on the toy below. The movement is different compared to the smooth motion of the eccentric cam. As the cam rotates the top half of the shell lifts at a relatively constant speed and then drops down suddenly.

 

The ‘pear shaped’ cam also has a different motion. The pear shaped cam lifts up the top part of the shell quite quickly and then it drops down just as quickly. However, for half a revolution the shell does not move at all.

 

     
 

 

   

QUESTION:

How can each cam design be changed to ensure that the top shell drops completely over the face inside the egg? Answer the questions by using diagrams and notes.

 
PDF FILE - CLICK HERE FOR PRINTABLE VERSION OF DESIGN SHEET
 

Using the design template shown below or a similar one, design four cam based toys. Include notes to help explain how each one works.

 

 

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