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）

Good quality, much better than stock couplings.

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.

After a few uses the coupler was stripped and kept coming off the z motor.

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 could not get my Z axis screw drive to remain level with the vertical frame of my Ender 3 V2. This little gem solved the issue as the gel inserts between the lower and upper halves allow flexing and the Z axis rod now remains straight. Great solution for a minor issue. 2 sets to a pack so youll always have a spare on hand.

5mm was small. Had to drill it out a little bit.

no spring back as with the traditional couplings. Nice tight, true turns when engaged!

These are most probably planned to separate, so these do not work for my use case: couplers for cartesian 3D printer z axis leadscrew. When moving z-axis, either one of these will separate. The grip is good, too good. Now I wasted two stepper motors because I cannot get these off without bending the axis.

The machining is horrible. I dont know if its made of aluminum or plastic.

The pull apart, there is actually nothing that would keep them together. I installed them and not long afterwards, my printer would make some weird noise. Sounded like a door hinge that needed some form of lubrication. Took a few hours to locate the source. Turns out the piece of hard rubber, or whatever it is, in between the two metal pieces would cause the noise. Sounded really awful, like my printer would fall apart any moment. The Z lead screw(s) would sway like the Eiffel Tower. Thought my screw(s) were lose, hi, hi. So I checked them as good as I could and they ran true. Now I am using solid coupler and all is good.