2PCS 6.35mm to 8mm Aluminium Plum Flexible Shaft Coupling 25mm Length 20mm Diameter Connector Flexible Coupler for 3D Printer CNC Machine and Servo Stepped Motor

Nice. inexpensive .

Great looking, perfect tolerances and work awesome.

One of the couplings the 5mm end actually measuring 6mm so it will not tighten on the stepper motor shaft (photo is next to the original coupler). I was able to get the other one to work for me, if you need both for dual z axis you might be out of luck with their quality control.

Doesn't work. 8mm lead won't fit in the 8mm hole. Hole is 1 or 2 mm smaller. Returned.

Was having issues with some of my finer prints on my 3D printer and found out the small travel of the Z axis was due to the coupling between the screw rod and the motor. I replaced the stock coupler with this one and the small errors I was getting was gone. This solved my layer adhesion issues between the layers and now my printer prints perfect. No more layer drift or leveling issues from one print to another. Awesome coupling and an easy upgrade for any printer.

I have an Ender 3 Pro that I had previously upgraded with a dual z-axis system to give better support to the x-gantry after fitting a heavier direct drive extruder system (BMG-Wind). This dual z-axis system uses two stepper motors driven from a single TMC2209 driver and a pulley system to keep the two lead screws in synch so that the bed should remain level when the stepper motors were idle. This system worked really well but, even though I tried hard to keep the various components involved carefully aligned, there was still a small amount of drag and a lot of mechanical noise from the lead screws during operation. I applied dry PTFE lubricant which did make a major improvement, but some mechanical noise was still left.I hoped that replacement of the fixed couplings, I had been using, with flexible equivalents, would better tolerate minor misalignments, and would be a good way of reducing the residual noise and implicit wear. I ordered this pair of 5mm x 8mm flexible plum couplings and used them to replace these fixed couplings. Installation was quick and easy with the supplied Allen wrench – it only took about 5 minutes to install them both and then another 10 minutes to realign the x-gantry so that it was parallel with the bed. I had no problems in tightening the Allen bolts onto the various shafts to get a secure grip on each. Operation was now very smooth and silent even though I had motors, lead screw nuts, a belt and pulleys all at work. I’m very pleased with the results – less noise means less wear, less error, better bed leveling and a quieter night’s sleep.There seems to be a variety of different brands of plum couplings available and other types of flexible coupling (helical spring and diaphragm) I don’t know how these other products would compare but these plum couplings worked very well for me, and they have my strong recommendation.

These coupler seem to me to be an upgrade from the stock Ender 3 couplers. The have rubber in the middle so they give a little bit. (pretty hard rubber in a confined space) I didn't notice improvement in print quality but I do believe the motors are protected to some degree and they keep everything nice and accurate.

This part made my prints come out a bit cleaner and helped with getting rid of some noise from the Z rod when the printer moves quickly. Better than the stock part on my printer