[V2.0] Adjustable Y-Axis Bearing Holder for MK3 - Fix That Rattle!

Version 2.0 Update

It became clear that overtightening the holder on the lateral adjustment screws can cause the bearing holder to crack. While this did not seem to affect print quality, it's not a good thing to have a cracked bearing holder.

I released an updated, thicker model. With version 2.0, there is about 0.5mm clearance between the frame and the holder, so be sure to measure your print so that it matches the dimensions of the STL.  

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My Y-axis for my MK3S+ is/was ALWAYS rattling. No matter how many times I replace the bearings or re-grease it with any kind of grease imaginable, it always rattled. Drives me absolutely nuts to listen to.

The rattle itself is due to the balls inside the linear bearings rattling against themselves and the rod. The y-axis then amplifies the sound like a speaker.

I've tried everything I can think of to fix it, but ultimately I think it's just a design flaw of the printer. The LM8UU-type bearings that are used throughout the printer are generally designed to be compressed into a sleeve. This preloads them onto the rod they are gliding against, reducing the overall clearance. And thus, the reducing the amount of rattle.

But the standard bearing holders do not provide nearly enough compression force to prevent the rattle. I believe the old U-bolt type holders would sort of “bend” the bearing a bit and apply a bit of compressive force. Which is why most of the reports of rattling have come up after the introduction of the newer bracket-type holder.

To get around this, I designed this bearing holder with 4 holes for screws. The screws can be tightened against the bearing itself, apply compressive force in 4 separate locations. The screws can be adjusted (tightened or loosened) as needed, or you can ignore them entirely. But if you're finding your y-axis rattling all the time, give these a try, and tighten the adjustment screws bit-by-bit until the rattling goes away.

Parts (For Each Holder)

• 4x screws (not too long)
• 4x square M3 nuts (~1.8mm thickness, same kind the MK3 kit comes with).
• 2x 18mm M3 screws (to attach the holder to the y-axis carriage).