Thoughts on Drylin rods and linear bearings  

Thoughts on Drylin rods and linear bearings

Hello.

Some time ago, I was adopted by my secondhand MK2s, missing many of the parts as it had been stripped down.

In the process of reconstruction, I decided to go with Drylin Linear Bearings along with the specially treated aluminum Drylin rods. I made this choice because my previous "PRUSA Clone" printer had really horrible (non) linear rods and linear bearings that might as well have had gravel inside. Also, the replacement rods and bearings from Amazon were not much better.

So, I brought my PRUSA MK2s back to life with a replacement MiniRambo from Ultimaker, some LDO steppers and Drylin linear bearings and rods straight from Germany. Over the course of many months the Drylin bearings dutifully and silently slid back and forth on the black Drylin rods, which do look great on a PRUSA.

Initial setup was tricky. The plain Drylin bushings worked best in the Z axis holders with no special attention needed.  The X axis worked well enough, but was very sensitive to tightening the X carriage cover after the 2.5 upgrade.  The Y axis needed special bushing holders from Thingiverse which did an outstanding job. The Y axis was very sensitive to misalignment. The least bit of misalignment and the Drylin bushing became very difficult to slide.  The new Drylins had some slop, but made up for it with more dampening, I think.  As advertised, the Drylin bushings are self-lubricating and the rods always felt slippery - ish.

Print quality was very good initially.  Over the past few months the print quality had been gradually declining after 1000 meters of filament or so.

And then I noticed the X carriage was fairly loose. The Drylin bushings had worn!  The black aluminum rods still looked like new, so I could have just replaced the inexpensive bushings.

Instead, I decided to try good quality hardened steel rods with GOOD quality linear bearings from a reputable vendor.  Test fitting one each of the "good" and the "Amazon" bearings for comparison, the good bearing slid smoothly and silently while the new and just unsealed Amazon bearing slid badly with much noise... on the same good quality shaft.

Put the steel rods and bearings on and things are now much tighter with very little slop. The X and Y carriages now move more freely and the printer doesn't seem to be noticeably louder.  And the print quality is now back to excellent, as good or better than when the Drylins were new.

So, for anyone considering using Drylin linear bushings and rods in their PRUSA, my experience has been that they offer no advantage over conventional rods and linear bearings of good quality, while being trickier to setup, having more play / slop and the bushings being prone to wear.

Drylin rods and bushings are a huge improvement over badly made rods and linear bearings,  but so are good quality rods and conventional bearings.  In short, it's probably best to avoid Amazon or eBay parts unless you're sure of the seller... I once paid full price for a counterfeit Gates Powergrip belt on eBay, so buyer beware!

Happy Printing!