HTD-3M Timing Belt Tensioner Pulley Smooth Tooth/Toothed Idler Width 11/16mm

The Smooth Tooth variant has a flat, un-profiled outer surface and is used as a non-meshing idler — the belt's flat back rides against it. The Toothed variant has HTD-3M tooth geometry machined into the rim and engages the belt's tooth side directly, providing positive tensioning without belt slippage. Choose Smooth Tooth for return-side idlers and Toothed for active tensioner positions.

Higher tooth counts produce a larger pitch diameter, which reduces the bending angle the belt must make around the pulley. For tight belt paths with limited space, a 20T or 25T idler works well. For longer belt spans where you want to minimize belt fatigue, a 36T–50T idler is a better fit. Match the tooth count to the available mounting space and the minimum bend radius specified for your HTD-3M belt.

Select the bore diameter that matches your shaft, standoff, or shoulder bolt diameter. Common choices are 5 mm for M5 shoulder bolts used in 3D printer frames, and 8–10 mm for larger CNC spindle or gantry shafts. If you are using a bearing insert, measure the bearing's inner race diameter and match it to the bore option.

No. These pulleys are machined specifically for HTD-3M belts with a 3 mm pitch and HTD tooth geometry. GT2 belts use a different 2 mm pitch and tooth profile and are not interchangeable. Using a mismatched pulley and belt will cause poor engagement, accelerated wear, and potential belt skipping under load.

Aluminum alloy provides a good strength-to-weight ratio suitable for the belt tension loads typical in 3D printers and light CNC machines. For heavy-duty industrial applications with sustained high belt tension, verify the load rating against your system's requirements. The alloy construction also resists corrosion in normal workshop environments without additional surface treatment.

These pulleys are sold as the pulley body only. Whether a bearing is pre-installed depends on the specific variant — please check the product images and variant description carefully. If no bearing is included, you will need to press-fit or slip-fit a compatible bearing (matched to the bore diameter) before installation.

It is not recommended. The pulley width should match or slightly exceed the belt width to ensure full tooth engagement and prevent the belt from riding off the pulley edge under lateral load. If your belt is 15 mm wide, select the 16 mm width variant for proper support.