1.5 Modulu 12T-40T Spur Gears pitch 4.71mm 45# Steel With Step Pinion Motor Gear

The tooth count determines your gear ratio. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, pairing a 12T pinion with a 24T gear gives a 2:1 reduction — the output shaft turns at half the speed but with twice the torque. Choose a smaller tooth count (12T–18T) for high-speed, lower-torque output, and a larger count (30T–40T) when you need more torque at lower RPM.

Measure your motor or shaft output diameter with a caliper before ordering. The bore must match your shaft diameter exactly for a secure fit. Available bores are 6mm, 8mm, 10mm, 12mm, 14mm, 15mm, and 16mm. If your shaft uses a keyway or set-screw, confirm the hub wall thickness is sufficient for your fastening method — contact us to confirm for larger bore sizes.

Yes. These gears follow the standard 1.5M module specification with a 20° pressure angle, which is the most common standard for metric spur gears. They will mesh correctly with any other 1.5M external spur gear or 1.5M rack of the same pressure angle, regardless of brand, as long as the tooth profile and module match.

45# steel (equivalent to SAE 1045) has a tensile strength of approximately 600–700 MPa in its normalized state, making it suitable for moderate continuous-duty drive applications such as CNC axis drives, robotic joints, and small conveyor systems. For very high shock loads or continuous heavy-duty industrial use, consider heat-treated or alloy steel alternatives. These gears are well-matched to stepper and DC motor outputs in the 1–50W range.

45# carbon steel has moderate corrosion resistance. For indoor, dry environments — typical of desktop CNC machines, 3D printer extruder drives, and lab automation — no additional treatment is generally needed. For humid or outdoor environments, applying a light machine oil or grease to the gear teeth will extend service life and reduce surface oxidation. If corrosion resistance is a primary requirement, consider stainless steel or plastic gears instead.

A step pinion features a hub with a stepped (shoulder) profile rather than a plain cylindrical hub. The shoulder acts as a positive axial stop when the gear is pressed or slid onto a shaft, preventing the gear from migrating along the shaft axis during operation. This is especially useful in motor pinion applications where axial positioning must be maintained without additional retaining hardware. It simplifies assembly and improves positional repeatability in your drivetrain.

Yes, with the correct bore selection. NEMA 17 stepper motors typically have a 5mm output shaft, so you would need to use a 6mm bore variant with a 5mm-to-6mm shaft adapter or a set-screw hub. NEMA 23 motors commonly use an 8mm or 6.35mm (1/4 in) shaft — the 8mm bore variant fits directly on an 8mm NEMA 23 shaft. Always verify your specific motor's shaft diameter in its datasheet before ordering.

For a 1.5 modulus gear, the pitch diameter (PD) is calculated as: PD = Module × Tooth Count. For example, a 20-tooth gear has a pitch diameter of 1.5 × 20 = 30mm. The outside diameter (OD) is approximately PD + 2 × Module = PD + 3mm. Use these values to verify clearance and center distance in your gear assembly before finalizing your design.