It's really crude and wonky at the time, but the concept works and with a bit more tuning and small redesign I think it will be quite usable.
In this first prototype I am using a M4 stainless steel threaded rod. I think I might want to move up to M6 rod as the M4 is a bit small for this sort of stuff.
The clutch system works, but needs some tuning. I made it so that the arms in the clutch (yellow in picture below) can be printed separately, so adjusting flex, length and spares can easily be done. The arms broke during testing today, actually that's what happened in the end of the youtube clip below. I planned to do the acetone treatment to the arms to make them more flexible and less brittle. Will try that next.
The blue piece is attached to the threaded rod. The biggest gear only rides loosely on the threaded rod and is engaged to the gear on the motor. As this gear rotates, the flexible clutch arms hit the rigid arms on the central (blue) part and in turn starts to rotate the threaded rod and moving the piston. If the force on the piston is too great, the clutch arms should flex and start slipping.
My hope is that his will eliminate all need for end stops and protection circuits, making it a much more crude but simpler mechanism.
- Capture.JPG (89.48 KiB) Viewed 4151 times
As shown in the video, it lifts 15kg (33lbs) easily. I was actually surprised by this. The motor and ESC seems to handle this load easily and power consumption was very low. But I suspect the readings wasn't too accurate. so more on that later.
