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Engineers and makers who rely on synchronous belt drives know the frustration of mismatched pulleys that introduce backlash, slip, or premature belt wear. This S8M 30mm timing belt drive pulley is designed for those who need a dimensionally accurate, torque-capable sprocket that installs cleanly and runs quietly across a wide range of shaft sizes and tooth counts.
Each pulley is machined from black steel with an S8M tooth profile and a 30mm belt width. The tooth count ranges from 22T to 40T, and the bore diameter spans 8 mm to 28 mm (approximately 0.31 in to 1.10 in), with optional keyway widths of 3 mm, 4 mm, 5 mm, 6 mm, or 8 mm depending on the bore selected. The hub width is consistent with the 30mm belt width standard, and the outer diameter scales with tooth count per S8M pitch geometry.
Typical use cases include CNC router and laser cutter axis drives requiring an S8M 30mm steel timing pulley, robotic arm joint actuators needing a keyed bore drive sprocket for positive shaft engagement, and industrial conveyor or indexing systems where a smooth tooth S8M pulley with a large bore range is required for flexible shaft compatibility.
| Belt Profile | S8M (Synchronous, 8mm pitch) |
|---|---|
| Belt Width | 30 mm |
| Number of Teeth | 22T, 24T, 25T, 26T, 28T, 30T, 40T |
| Bore Diameter | 8 mm – 28 mm (see variant options) |
| Keyway Width | Without keyway / 3 mm / 4 mm / 5 mm / 6 mm / 8 mm (see variant options) |
| Material | Steel |
| Finish | Black |
| Outer Diameter | See variant options |
| Hub Width | See variant options |
| Weight | See variant options |
The tooth count determines the pulley pitch diameter and drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the speed reduction ratio. For example, a 22T driving pulley paired with a 44T driven pulley gives a 2:1 reduction. Use a belt length calculator with your center distance and both tooth counts to confirm belt compatibility.
Measure your motor or gearbox output shaft diameter with calipers. Select the bore that matches exactly — a bore that is too large will cause runout and vibration even with a keyway. Available bores range from 8 mm to 28 mm. If your shaft is an imperial size (e.g., 1/2 in = 12.7 mm), select the 12.7 mm bore option.
A keyway is recommended whenever the pulley must transmit significant torque or resist axial movement under load. The correct keyway width is determined by your shaft existing keyway slot — measure the slot width and select the matching option (3 mm, 4 mm, 5 mm, 6 mm, or 8 mm). If your shaft has no keyway slot, select without keyway and secure with a set screw if needed.
This pulley is designed to the S8M pitch standard (8 mm pitch) and is compatible with any S8M synchronous timing belt that is 30 mm wide. Confirm that your belt is rated for 30 mm width; narrower or wider S8M belts will not track correctly on this pulley.
Steel construction provides substantially higher torque capacity and rigidity compared to aluminum or plastic pulleys of the same size. The exact torque rating depends on the bore, keyway configuration, and belt tension in your specific system. For high-torque applications, always use a keyway variant and ensure the set screw is properly torqued against a flat on the shaft.
The black finish provides a degree of surface protection, but steel pulleys are not inherently corrosion-proof. For humid, wet, or outdoor environments, apply a light machine oil or anti-corrosion coating periodically. For fully corrosion-resistant applications, consider stainless steel or aluminum alternatives.
Use the standard synchronous belt length formula: L = 2C + π(D1 + D2)/2 + (D2 − D1)²/(4C), where C is the center distance and D1/D2 are the pitch diameters of the two pulleys. Pitch diameter = (Teeth × Pitch) / π. For S8M, pitch = 8 mm. Round up to the nearest available S8M belt length and adjust center distance accordingly.
