Derailleur actuation experiment

A failed experiment on how to actuate a rear derailleur with a servo. The servo would be mounted to the barrel adjuster, & a rod passed through the barrel adjuster.

The rod would have teeth, & the servo would draw the rod in/out using a rack & pinion drive.

The rod would be connected to a plate with a non-circular slot in it to constrain a pin located in the cable anchor bolt hole.

This way, the circular movement of the servo would cause the parallelogram mechanism to force a lateral movement.

The design problem here is that the rod is about 0.115" thick & would bend immediately. Unless you drill out the barrel adjuster & stiffen it up considerably, this design is kind of useless. You can play with the motion (I think) in the assembly file.

If you actually manage to make this work, please let me know. I'd be intrigued.