About Timing Belts

This page is part of the Cupcake CNC build sequence.

Cupcake CNC uses timing belts to move its various parts. Timing belts are belts made of reinforced rubber with little teeth molded onto the inside, which mesh with slots in pulleys. Cupcake CNC uses continuous belts 6mm in width, with 2mm between teeth (the GT2 drive system).

The belts we use have silkscreened part numbers which include the number of teeth on the belt. For example, this belt has the code: GATES GT 2MR193 2655MC


The number after the "R" indicates the number of teeth on the belt. In this example, for instance, the belt has 193 teeth.

Fitting belts

We mount our idler pulleys in slots to allow you to tension the belt properly, but even when the pulleys are at their loosest, it can be tough to get the belt around them. Often, it is simplest to run the belt around all the pulleys except for the small metal drive pulley first. Then get the belt partway around the drive pulley, and then rotate the pulley to pull the belt onto it.

Update: If you undertighten a timing belt, it will slip. If you overtighten it slightly, the belt will vibrate during motion causing increased audio noise (which can be fixed later). If you really overtighten it, you will cause increased stress on the motors and possibly increased friction on that axis's motion.

Belts should be a little loose, but not so loose that the teeth slip.

Next step: Cupcake Electronics Assembly

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