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 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.

Hello.... Ware schnell angekommen..... Ware sofort verbaut und für tiptop befunden Thx

Good quality, much better than stock couplings.

Very good quality product. will recommend to anyone

These work better than the machined spring style shaft couplers because they handle offsets better (when the shaft is spinning and is slightly misaligned) and because it centers the shaft better - the set screws clamp coupler, not the shaft (normally set screws push the shaft slightly to one side or another as they interface with the shaft itself - this can also lead to small divets in the shaft where the set screws dug in). Quality is quite good, too!

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

One of them was straight but the other was completely out of round. These were purchased for the Z axis on my 3D printer and having any wobble was not acceptable.. I didn’t have to measure the runout to see how bad these were it was visible. They’re definitely not appropriate for a 3D printer.

Good idea, I hope it works

Both of the ones I received were so tight, I doubt they would separate in the event of a nozzle crash. Ironically, the one I did use slipped on the motor side, causing a nozzle crash, despite being tightened to the point I was worried about stripping threads.

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.