Locking Rigid Shaft Coupling

1.5 degree tapered threads on coupling and nuts enable the coupling to lock onto the shafts.

Stepper Shaft Diameter: 5 mm with flat
Shaft Diameter: 8 mm
Overall length: 25 mm

I have not installed this in an application, I just created it to see if I could get PLA to grab tight enough to a round shaft. It grips very well. The key component is the PTFE tape applied to the threads. This tape drastically reduces the friction between the nut and coupling threads.

8/17/13 UPDATE:
Per