CoreXY Belt Routing 

One of the most important parts for corexy movement is belt routing. Here’s a guide to the mechanics of corexy belt routing pulley layout in order to get accuracy and constant belt tension.

Belt Routing Methods

There are two main ways to implement the corexy belt path. Either a stacked pulley arrangement or a crossed belt also known as a belt twist. The crossed belts design allows for each belt to take different paths, creating an x-shape configuration The stacked belt path simplifies alignment and belt tensioning. There is an increased complexity in this routing due to having two different height motor shafts, but it also eliminates belt tensioning issues.3d printer resolution may be affected when the toothed belt runs on a smooth idler as it results in a  curtain effect pattern also known as ripple

Crossing Belts vs Stacked Belts

While both belt routing methods can be equally effective if implemented correctly. But belt path designs that move the belt teeth against smooth idlers, and designs that run teeth against the teeth of the idlers

It is possible that the toothed pulleys produce more noise and some people claim that the teeth against the smooth pulley causes irregular offsets in their printing from belt stretching but a smooth belt surface on a smooth pulley reduces ripples and may be a simple way to increase the print quality, as it would allow for more of an even printing process. This routing path has its negatives in relation to artifacts within printed parts that could appear on one side of the gantry; however, this route also allows for straight belt paths without any twists which might give off smoother prints and have less risks when compared with other designs.

Stacked Belt Path – Offsetting The Stepper Motors

Offsetting the stepper motors with stacked belt path pulleys may give the belts a clean run and simplify belt alignment. A printer’s motors can be offset at different heights so that the belt routing runs a straight belt path and doesn’t have to be twisted. But this corexy belt routing path would also mean that on one side of the gantry the belt would have the teeth on the side of the idler wheel which wouldn’t run as smooth and could lead to artifacts within printed parts.

Crossing Belts – Twisting The Belt Cross Over

The Railcore design had a lot of influence on the SolidCore 3D Printer. The belt path of both machines cross in an “x” shape, but many people prefer the stacked belts approach. Twisting the belts can cause the belt to ride on the flanges of the pulleys which causes wear on the belts. However, there are many corexy designs that work very well with this mechanical arrangement. The main concern is that belt tension varies from one height level to another because it has different lengths created by varying tensions depending on how tight they are wound around their respective pulleys .

Belt Layout & Belt Tension

Many people prefer the stacked belts approach. Twisting the belts can cause the belt to ride on the flanges of the pulleys which causes wear on the belts. However, there are many corexy designs that work very well with this mechanical arrangement. The main concern is that belt tension varies from one height level to another because it has different lengths created by varying tensions.

Parallel Belt Paths

The corexy belt path must be parallel to the linear guides as the carriage moves along the axis. This means that there is a x-shape configuration with two points of contact at both ends. The length of the belt may vary in tension. Belt tension may increase or decrease as it moves along the axis. The length of the twisted segment must maintain constant tension, otherwise the twist will cause the belt tension to vary. Mark Rehorst has an excellent blog that explains the corexy belt routing. Mark Rehorse’s Blog

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