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）

one bolt came jammed and the head was already cammed out, the second one didnt have the relief cut all the way through so tightening is impossible

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.

Holes out of alignment. They wobble. The hole for the motor is skewed enough to be visible. Probably done free hand on cheap drill press. I payed alot for quality got junk. Shame.

All good as expected

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

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.

I bought two sets of these and both were bad. They are cheap so I did not go through the hassle of returning them again. I strongly recommend looking elsewhere. These are NOT the ones you should get. I struggled for days trying to figure out why the printer was failing, only to find out the problem was with the coupler. Bad on me for trusting a cheap product.

They would not clamp to the stepper motor shafts of my sidewinder X1 no matter how much I tightened the bolts.