Hello, I am designing a circular joint to connect the motor shaft to another part. As you see from the photo, the motor shaft is of D-shape. It allows a screw to fix it to another part. I made a hole of M4 size and used a 3D printer to print the circular joint. Then, I used a tapper to create the screw thread. However, even I tried to tighten the screw, the circular joint does not rotate with the motor shaft. Anybody knows the reason and how to fix it?