Befenybay 2PCS 5mm to 8mm Aluminium Plum Flexible Shaft Coupling D20 L25 Connector Flexible Coupler for 3D Printer CNC Machine and Servo Stepped Motor（5x8mm）

To be fair I didnt try to adjust the cheap ones that came on the printer, or re-seat them in any way, but removing the original ones and installing these got rid of all the low pitch squeaking I got when rapidly adjusting the z health on my Cartesian printer.

Good quality, much better than stock couplings.

The 5mm side for the stepper was to small. I ended up stripping the bolts to get it tight enough.

Good idea, I hope it works

Sort of small

One of them was straight but the other was completely out of round. These were purchased for the Z axis on my 3D printer and having any wobble was not acceptable.. I didn’t have to measure the runout to see how bad these were it was visible. They’re definitely not appropriate for a 3D printer.

For some reason the flexible couplers milled from a single piece of aluminum tend to shear on my DIY CNC machine on both the X and Y axis. Ive tried different brands and suppliers, including the one in the photo, with the very same results. Within 6 hours of run time it breaks on the simplest of carves, ruining my workpiece. As you can see in the photo and the pictured break, one has to question the mill stock used vs. who mills these from that stock. However, since changing to this 3 piece design, Ive been running fine without any issues or mid-carve failures!!! Thanks!

Good product