2PCS 5mm to 8mm Aluminium Plum Flexible Shaft Coupling D20 L25 Connector Flexible Coupler for CNC Machine and Servo Stepped Motor（5x8mm）

I bought these couplers to replace the horrendous ones that came with the Biqu B1SE, as well as on an Ender 3 I had (which to be honest didn't need replacing, but I had a two pack so I threw it on).This style of coupler provides a couple of advantages:-The set screw clamps the coupler around the leadscrew, rather than screws directly into the leadscrew. The stock B1SE coupler has a pair of setscrews that go directly into the leadscrew, and not only did this mean that you can never properly center the leadscrew (because you had to clamp setscrews into it from both sides), but that it also came loose quite often. Nevermind the fact that it can damage the leadscrew itself. The Befenybay couplers required only tightening one set screw and that was it- no fuss and never came loose again. This alone fixed a major pain point of that printer.-The design compensates for minor misalignment. If your leadscrew is extremely bent this probably won't fix any Z-problems you have, but for minor misalignments they can and do work very well. Again, the B1SE has a very long leadscrew which has a very slight offset between the gantry and stepper; this is incredibly obvious because the leadscrew is not parallel to the vertical extrusions and wobble around a lot despite efforts squaring the frame and moving things around to get them perfectly aligned. Installing this coupler, that leadscrew is now parallel and does not show the same level of wobble as before. Printing a test cylindrical tube also shows no z-banding.-It provides an extra level of protection. If something causes your Z-axis to jam or otherwise smash into the bed, the two halves of this coupler actually separates completely allowing the stepper to free spin. In my case, I forgot to remove a tool I used to lock the z-axis into place during maintenance, and the separation of the coupler avoided any additional stress I would have placed on the printer components. I see some comments about this coupler separating prematurely during normal printing, but I hadn't experienced that problem. I can see that if coupler tolerances are bad, this can happen, but also you should be checking to make sure that your gantry is able to move up and down freely (remove the leadscrew and just move it up and down with your arms).Overall, this is a minor improvement over traditional coupler designs. I would not necessarily buy these simply for the sake of an upgrade (as I said, the stock Ender 3 coupler works ok); but if you were already looking to replace couplers for any reason, I think these are a no-brainer to get.

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. I've 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, I've been running fine without any issues or mid-carve failures!!! Thanks!

This fit perfectly on my Ender 3 as well as a couple of Ender 3 clones that I had sitting around. My ender was having trouble raising the z axis due to a faulty coupler from the factory. A cheap upgrade that can make all the difference!

I tried the other type of couplers that look more like a spring on the Z axis lead screws on my Ender 5 Plus but they stretched out and messed everything up. Got rid of those and replaced them with these. These work great and support the weight of the bed with ease. They are not really flexible so these will not solve any Z banding issues but they do stay together and don’t expand like the other type did. They don’t get 5 stars from me because of lack of flexibility but they are decent enough to get 4 stars.

Perfect design that balances stability and flex for better print quality

I should have listened to the other reviewers. Not only was the machining and tolerances pretty far off for a precision job for properly aligning a leadscrew but the small screws are super bad quality (see picture close up of the striped screw head). The 5-8mm holes are pretty far off causing you to need to extra tighten the screws to grab hold of your leadscrew and stepper shaft. After I realized how terrible the bottom screw was (to the stepper shaft) I replaced the top screw with the one that was in the factory coupler and it never stripped. At the very least if you still feel like many of us don't know what we are talking about and you still want to give this a try, replace the screws with the ones that came with your stock coupler. Its a good thing I did that or else I would have lost the stepper and the leadscrew to a wobbly, out of alignment poorly manufactured coupler. I have yet to find a solution other than properly aligning everything with custom designed 3d printed parts and the solid factory coupler. After this failure I have pulled out the calipers to make sure everything was aligned properly and my issues were fixed and I never needed this part anyway. One star for wasting my money and costing me a new stepper motor.

I did some upgrades to my ender 3v2. I went with a dual z setup with 2 motors and it has a timming belt. While I had everything apart I thought it would be a good time to upgrade the couplings.

Added this to my Ender 3 printers to help with z banding issues. My print look really nice now.

I was experiencing some pretty noticeable z wobble on a custom Cartesian printer I was building. Changing the couplers to these was a night and day solution. My z wobble is completely gone!

Wurde auf der Firma bei einer notreparatur verwendet und passte auf Anhieb. Die Übertragung des Drehmoments war sehr zufriedenstellend.

Mi hanno risolto un problema meccanico altrimenti difficile.

A amélioré la qualité de mes impressions sur une sovol sv01pro.

Très bon matériel, semble fiable et durable! Les têtes de visses pourrais devenir fragile en cas de serrages trop forts ou répétés.