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）

There are better couplings on Amazon. Not only do the allan keys bolts strip very easily but the orange part in the middle separates easily as well if you apply pressure to it, making it a useless coupling for a more heavy duty attachment. I now have to throw these out because I couldn’t allan the bolt to loosen it because it got stripped so bad and it’s not due to poor technique or have it too tight. It’s just cheap. Wouldn’t recommend

All good as expected

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.

These are bored off center and wobble all over the place. There is noway they will work on a CNC printer. I would not purchase these at all.

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.

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.

I installed these and noticed it wobbling immediately when rotating the z lead screw. So I reinstalled these in several different ways (loosening/tightening grub screws, reseating coupler on lead screw then on motor and vis versa, and tried correcting uneven coupler by taking it apart and assembling it in different ways). I looked up and watched several different videos just to make sure I wasn’t installing these wrong. Nothing worked. After spending several hours on this coupler, I reinstalled the stock coupler and wobble is completely gone. I really wanted this coupler to work but in the end I had to accept that this coupler is poorly built. I will be returning and looking for a better built coupler than this one.

Semplicemente dopo averli installati sulla mia stampante 3d ho riscontrato un movimento delle aste filettate non trascurabile. Da una parte un po me lo aspettavo vista la natura del pezzo (due pezzi separati con nel mezzo del materiale plastico) ma non così tanto. Il problema secondo me deriva dal non perfetto allineamento tra il foro da 5 mm e quello da 8 e questo accentua le oscillazioni.

I had to add a layer of aluminum foil around my Nema 17 stepper shaft to actually get it to bite tight enough to have a firm grip. They should design these things with a D-Bottom the same shape as a Nema 17 shaft so they will actually grab....

These coupling did not last thru the first minor jam on m Tops cnc