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）

Needes for 10mm stepper shafts amd 1605 ball screws.

To be fair I didnt try to adjust the cheap ones that came on the printer, or re-seat them in any way, but removing the original ones and installing these got rid of all the low pitch squeaking I got when rapidly adjusting the z health on my Cartesian printer.

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

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.

For some reason the flexible couplers milled from a single piece of aluminum tend to shear on my DIY CNC machine on both the X and Y axis. Ive tried different brands and suppliers, including the one in the photo, with the very same results. Within 6 hours of run time it breaks on the simplest of carves, ruining my workpiece. As you can see in the photo and the pictured break, one has to question the mill stock used vs. who mills these from that stock. However, since changing to this 3 piece design, Ive been running fine without any issues or mid-carve failures!!! Thanks!

Definitely not a precision product, but the work for hobby applications.

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

The plastic slides right out whether vertical or horizontal. The bottom of the clamping screw hole was foil thin. it wouldnt clamp on the stepper shaft

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

this coupler has one job: be straight. It isnt. Its off by at least 2-3 degrees, which takes considerable torque to overcome if your motor is mounted firmly. I think (think, not positive) the problem is in the rubber piece, not the aluminum. The rubber is tight fitting and allows no play, which would be good... if it were straight. I sanded the rubber ears down and introduced a bunch of slop so that my motor would quit stalling as it binds up every rotation. I used it for something that doesnt require any precision so it was good enough after I fixed it, but i would not recommend this for any kind of 3d printer or CNC.