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）

Factory coupler that came with the 3d printer striped right out of the box. Ridiculous I had to order parts the day I bought it. Luckily this piece fits to spec. And I have a second one just in case.

Not much else to say other than these kept sticking on my dual z-axis Ender 3 Pro and causing terrible banding on prints. Woke up to a print I set overnight to see that one of them completely failed in the middle of the night and fell apart.

I like these type of coupler alot better than the set screw type because the set screw type you can never get them exactly on center. with these friction type they stay on center and nothing damages the lead screw

I should have listened to the other reviewers. Not only was the machining and tolerances pretty far off for a precision job for properly aligning a leadscrew but the small screws are super bad quality (see picture close up of the striped screw head). The 5-8mm holes are pretty far off causing you to need to extra tighten the screws to grab hold of your leadscrew and stepper shaft. After I realized how terrible the bottom screw was (to the stepper shaft) I replaced the top screw with the one that was in the factory coupler and it never stripped. At the very least if you still feel like many of us dont know what we are talking about and you still want to give this a try, replace the screws with the ones that came with your stock coupler. Its a good thing I did that or else I would have lost the stepper and the leadscrew to a wobbly, out of alignment poorly manufactured coupler. I have yet to find a solution other than properly aligning everything with custom designed 3d printed parts and the solid factory coupler. After this failure I have pulled out the calipers to make sure everything was aligned properly and my issues were fixed and I never needed this part anyway. One star for wasting my money and costing me a new stepper motor.

Works well on Z-axis lead screw for my Ender 3, and is a definite upgrade to the stock coupler. The finish is decent, and seems pretty solid. My only complaint is that the coupler will come apart fairly easily if you apply any form of tension pulling on the coupler, which can get very annoying if youre used to pulling up on the X-axis gantry to manually raise it. Thats 100% a design shortcoming specific to my application, and not a fault from manufacturing.

The bottom of the clamping screw hole was foil thin. Couldnt figure out why it wouldnt clamp on the stepper shaft, got to looking a little harder and saw the bolt bottomed out on the other side of the slot.

Such a simple upgrade elevated the z axis binding o had after upgrading to dual z axis motors

To tighten it you need to apply excessive force on the screws. There is the danger to destroy the threads on the top of the screws and not be able to remove it.

In my case the two shafts were not concentric causing horrible wobbles in my 3D printer. It’s possible the plastic insert was matched to the coupling pair. That’s not ok if you never take these apart. They are being returned.

Der Kunststoff ist zu weich - und die Schraubenköpfe auch. Resultat: Man braucht viel Drehmoment um die Schrauben anzuziehen, damit die Kupplung nicht auseinander rutscht, und dabei macht man die Schraubenköpfe rund. Drei von vier gingen noch vom Schaft, eine nicht mehr und musste abgeschliffen werden. Für z.b. die Z-Achse an einem 3D Drucker wäre diese Schaftkupplung noch brauchbar, aber wer hat schon einen 8mm Schaft an einem Nema 17? Geht Retour.