GT2 smooth 20T-size idler pulley with bearing for 6 mm belt, 3 mm bore

Smooth idler pulley with an integrated bearing and a nominal 20T-equivalent size, intended to guide the back of a 6 mm GT2 belt on a 3 mm axle or screw.

Compared with the 16T-size version, it provides a larger belt path radius but also requires more space. Pulley size is part of the mechanism geometry and should be respected when replacing an existing component.

Features

• Type: smooth idler pulley with bearing.
• Running surface: smooth, without teeth.
• Nominal size: 20T equivalent.
• Compatible belt width: 6 mm.
• Bearing inner diameter: 3 mm.
• Nominal mounting: 3 mm axle or screw, usually M3.
• Body material: aluminium.
• Bearing: integrated.
• Side flanges: yes.

Applications

• Tensioners contacting the back of a GT2 belt.
• Smooth belt guides and returns in Cartesian axes.
• RepRap and Prusa i3-derived mechanisms using an M3 mounting screw.
• Custom 3D printer and CNC machine projects.

Installation and alignment

The screw should secure the bearing inner race without preventing the pulley from rotating. Use suitable spacers or washers to prevent the bracket from pressing against the flanges.

After installation, check that the pulley rotates freely and that the belt remains centred. Continuous contact with one flange usually indicates misalignment, a tilted mounting screw or a height difference relative to the other pulleys.

Compatibility

It is compatible with the back of 6 mm GT2 belts, including our standard GT2 belt and wear-resistant coated 6 mm GT2 belt.

When the toothed side of the belt contacts the pulley, use the GT2 20T toothed idler with a 3 mm bore. The smooth version should not run against the belt teeth unless the machine design explicitly requires it, as this changes belt support and bending.

It can serve as a replacement in a RepRap or Prusa i3-derived printer only when the M3 mounting, pulley size, 6 mm belt width and available bracket clearance all match.

Do not directly replace it with a 16T-size pulley without checking the tensioner position, belt length and possible interference.

Contents: 1 idler pulley with bearing.