After resolving an initial issue with Z-axis movement, my Creality Ender-3 V2 enters my 3D printing pool. I mainly got it because it was becoming a hassle to switch my MatterHackers Pulse XE between PLA and PETG printing. My intent is to leave the Ender-3 V2 loaded with PLA and the Pulse XE loaded with PETG. I’m sure that’ll only last for as long as it takes for one of these printers to develop a problem, but I’ll figure out how to cross that bridge when I come to it.
The best news is that the extra cost for V2 was worthwhile: this printer operates without the whiny buzz of older stepper motor drivers. It’s not completely silent, though. Several cooling fans on the machine have a constant whir, and there are still some noises as a function of movement. Part of that are the belts against motor pulley, and part of that are roller wheels against aluminum.
These rollers are the biggest mechanical design difference between Creality’s Ender line and all of my prior 3D printers. Every previous printer constrained movement on each axis via cylindrical bearings traversing over precision-ground metal rods. One set for X-axis, one set for Y-axis, and one set for Z-axis. To do the same job, the Ender design replaces them with hard plastic rollers traversing over aluminum extrusion beams.
The first and most obvious advantage to this design is cost. Precision ground metal rods are more expensive to produce than aluminum extrusions, and we need them in pairs (or more) to constrain motion along an axis. In contrast, Ender’s design manages to constrain motion by using rollers on multiple surfaces of a single beam. In addition to lower parts cost, I guess the assembly cost is also lower. Getting multiple linear bearings properly lined up seems more finicky than bolting on several hard plastic rollers.
Rollers should also be easier to maintain, as they roll on ball bearings that keep their lubrication sealed within. Unlike the metal guide rods that require occasional cleaning and oiling. The cleaning is required because those rods are exposed and thus collect dust, which then stick because of the oil, and then the resulting goop is shoved to either end of range of travel. Fresh oil then needs to be applied to keep up with this migration.
But using rollers also means accepting some downsides. Such a design is theoretically less accurate, as hard plastic rollers on aluminum allow more flex than linear bearings on precision rods. Would lower theoretical accuracy actually translate to less accurate prints? Or would that flex be completely negligible for the purpose of 3D printing? That is yet to be determined.
And finally, I worry about wear and tear on these roller wheels. Well-lubricated metal on metal have very minimal wear, but hard plastic on aluminum immediately started grinding out visible particles within days of use. I expect the reduced theoretical accuracy is minimal when the printer is new but will become more impactful as the wheels wear down. Would it affect proper fit of my 3D printed parts? That is also yet to be determined. But to end on a good note: even if worn wheels cause problems, they should be pretty easy to replace.