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）

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.

I can see where they have utility and where some people probably love them for certain applications, but I absolutely couldnt stand them at all. I bought a pair to use for an Ender 3 V2 printer when I was doing a dual-Z axis upgrade and just the littlest bit of pressure sent these couplers flying apart. For example, if you had even the slightest collision with your print bed, you were going to have to go in there and re-seat at least one coupler. And this is where I say I can see where they have utility for some people. I can see where that would seem like a perk to immediately limit the collision by disengaging from the drive train so you didnt smash your print head down into the print bed. But I found these would also separate during normal course of use causing inconsistent z-height adjustments on prints and horrible print quality. I went back to use the flexible aluminum couplers which are still fully connected but spiral cut in the center to allow for some margin of error in a collision, and flexibility for misaligned screw rods, but still fully connected with spring-back to ensure more consistent operation for long periods of time.

Quality of coupling itself and screws is really bad. I would avoid as it is not worth the hassle of ruining your motor is the coupling seizes and you are unable to get it off.

works great for helping z axis stress. Printer moves much smoother now after this and a dual axis upgrade

Will separate when pulled. Doesnt help screw wobble, to stiff of nylon insert. Screws strip easily, wont grip shafts without a lot of torque.

Works great for my Wanhao clone, the monoprice maker select plus

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

Should work fine on a 3d printer, but its horrible on a CNC machine.

Sort of small

The children wanted to extend the shaft of the motor and in turn, go from an 8mm to 6 mm shaft. This did the trick.