At home engineering fun. disc and rod drum driver

[JasonLA]

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

[FredGarvin]

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?

[TVP45]

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.

[JasonLA]

I also think the tear/kidney shaped disc is the way to go.

thanks for all of your suggestions.