3D printers touting high-quality "linear rails" have sprouted up all over the market. Find out if a linear rail 3D printer is legitimately better or just a marketing sham.
Linear rails, also referred to as linear motion guides and linear slides, are common motion components used to achieve smooth sliding motions. They can be found in 3D printers, CNC mills, waterjet cutters, and the like.
A linear rail consists of a stiff, steel rail, along which a carriage slide. Most commonly, the carriage contains recirculating ball bearings that provide contact points between the carriage and the rail, as depicted above. This enables a smooth sliding motion as the balls roll between the surfaces. The shape of the shaft enables the carriage to stay locked on with tight tolerances, restricting the motion to strictly linear directions.
Linear rail 3D printers utilize the numerous advantages of these linear rails to, supposedly, achieve better motion. So, how plausible are these claims? Let’s take a look.
Most 3D printers sport hardened-steel linear rods, used in tandem with linear ball bearings. This combination has worked well for thousands of printers and users, so what more do linear rails bring?
Of course, nothing is perfect. In a few areas, linear rails fall short of rods in 3D printer applications.
So, in practice, how do linear rail 3D printers fare?
In the DIY scene, many users have “upgraded” their Prusa-style 3D printers, such as the CR-10 and Anet A8, to linear rails. Picking linear rails for CoreXY motion systems is also common. In both cases, the rails’ ease of mounting and smooth motion lend them much of their appeal.
In commercially-available machines, linear rails have found their way into acclaimed 3D printers from Markforged, Atom, Cetus, and E3D, just to name a few. All of these machines take advantage of linear rails’ superior motion. As an example, the Cetus (depicted above) also takes advantage of the lack of rotational movement and incredible stiffness of these rails, enabling a more inexpensive, bare-bones motion system. It demonstrates the potential of linear rails in weight and material reduction.
Thus, while most 3D printers still use linear rods and bearings, linear rails have definitely seen success on the market, playing to their known advantages. The marketing around these rails definitely aligns with accurate facts and the experiences of users.
Linear rail 3D printers have a lot going for them. But are they really better?
From a pure performance perspective, yes, linear rails are truly superior. They offer greater precision, better mounting, and smoother motion, improving print quality and printer reliability. With good design choices, weight and cost savings are also possible, as demonstrated by the Cetus 3D printer.
There is, however, an elephant in the room: the price. Traditional linear rods and bearings are perfectly usable at just a fraction of the cost, making linear rails difficult to recommend to everyone. If you’re on a tight budget and don’t need the best possible performance, linear rails may not be the best choice.
Thus, we have our verdict: Linear rails are better. They’re just not for everyone.
Feature image source: Cetus3D / Kickstarter
License: The text of "Linear Rail 3D Printer – Really Better or Just a Hype?" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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