At home engineering fun. disc and rod drum driver

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Discussion Overview

The discussion centers around a mechanical engineering problem involving a drum head being driven by a rod that moves in response to changes in the radius of a disc. Participants explore different mechanisms to achieve a desired motion characterized by a gradual raise and an abrupt drop of the drum head, along with a kink that the rod must navigate.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Jason describes the mechanism involving a rod and a disc, seeking suggestions for achieving the desired motion.
  • One participant asks whether the goal is a gradual change in linear motion or a straight cyclical motion, suggesting a round disk with a peg for smooth cyclical motion if the latter is desired.
  • Another participant proposes using a tear drop-shaped cam to achieve the gradual change, emphasizing the need for a generous radius at both ends.
  • A different suggestion involves spring loading the mechanism and using a reverse disk for lifting.
  • Jason expresses agreement with the tear/kidney shaped disc as a preferred solution based on the suggestions received.

Areas of Agreement / Disagreement

Participants present multiple competing views on how to achieve the desired motion, with no consensus reached on a single solution.

Contextual Notes

Participants have not fully explored the implications of their proposed designs, and there may be missing assumptions regarding the mechanical properties and constraints of the system.

JasonLA
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I am driving a drum head with a rod. The rod goes up and down as the radius of a disc changes length (please see attached PDF). There is a gradual raise of the drum head, and then an abrupt drop. But there is a kink that the rod needs to overcome.

Any suggestions on how to achieve this motion?

thanks
Jason
 

Attachments

Engineering news on Phys.org
Are you attempting to get that gradual change in the linear motion or do you want a straight cyclical motion? If just a cyclical motion is desired, use a round disk with a peg at some radius from the center. Attach the rod end to the pin. That will give you a smooth cyclical motion.

If you want that gradual change, how about making the cam a tear drop shape with a generous radius at both ends?
 
There are more complex solutions I can give you, but the simplest thing is to spring load it down and lift it with a reverse disk.
 
I also think the tear/kidney shaped disc is the way to go.

thanks for all of your suggestions.
 

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