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When a noisy spur gear or a mismatched module causes vibration, lost motion, or premature wear in your drive train, the fix starts with the right helical gear. These 45# steel helical gears are engineered for makers, CNC builders, robotics integrators, and small-machine designers who need reliable, low-noise torque transfer without sourcing custom parts.
Each gear is machined from 45# medium-carbon steel and finished with a blackening (black oxide) surface treatment that reduces friction and provides a baseline level of corrosion resistance. The module is 1 (Mod 1), with tooth counts ranging from 13 T to 30 T and bore diameters from 6 mm (0.24 in) to 16 mm (0.63 in). Outer diameters scale with tooth count — typically 15 mm (0.59 in) for 13 T up to approximately 32 mm (1.26 in) for 30 T.
Typical use cases include: CNC router Z-axis and rotary-axis drives requiring low backlash helical mesh; DC-motor gearbox stages in mobile robotics and AGV platforms; and compact industrial automation sub-assemblies where axial load capacity and quiet operation are priorities over a straight-cut spur gear.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Surface Treatment | Blackening (Black Oxide) |
| Module (Mod) | 1 |
| Tooth Count | 13 T / 15 T / 20 T / 26 T / 30 T |
| Bore Diameter | 6 mm / 8 mm / 10 mm / 12 mm / 14 mm / 15 mm / 16 mm |
| Outer Diameter (approx.) | See variant options |
| Face Width | See variant options |
| Helix Angle | See variant options |
| Pressure Angle | 20° |
| Gear Type | Helical Pinion Gear |
| Pack Quantity | 1 / 2 / 4 / 10 pcs |
| Weight (per piece) | See variant options |
Tooth count determines your gear ratio when paired with a mating gear. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, pairing a 13 T pinion with a 26 T gear gives a 2:1 reduction. Smaller tooth counts (13–15 T) are common on motor shafts (driving pinions), while larger counts (20–30 T) are used on the driven side for speed reduction and torque multiplication.
Match the bore diameter to your motor shaft diameter. Common stepper motor shafts are 5 mm or 6.35 mm (1/4 in); NEMA 23 steppers typically use 6.35 mm or 8 mm shafts; servo motors often use 8–14 mm shafts. If your shaft is slightly undersized, a set-screw hub or keyway can compensate — confirm the bore and hub depth before ordering.
45# steel has a tensile strength of approximately 600–800 MPa depending on heat treatment. For Mod 1 gears, the allowable tangential load per unit face width is moderate — suitable for light-to-medium duty drives. For heavy shock loads or continuous high-torque applications, consider specifying face width and applying a service factor. Contact us with your torque and speed requirements if you need confirmation.
Black oxide provides a thin conversion coating that offers mild corrosion resistance — significantly less than zinc plating or stainless steel. For indoor, dry environments it is adequate. For humid, outdoor, or washdown environments, apply a light machine oil or grease to the gear teeth and bore after installation to extend service life.
Helical gears and spur gears of the same module cannot be directly meshed — they require matching helix angles. These gears are designed to mesh with a mating Mod 1 helical gear of the same helix angle (and opposite hand for parallel-axis drives). If you need to interface with a spur gear, a transition stage or a different gear type is required.
Single-piece orders are ideal for prototyping, replacement, or low-volume builds. Packs of 2, 4, or 10 offer a lower per-unit cost and are suited for production runs, spare-parts inventory, or multi-axis machines that use the same gear specification on several axes. Select your pack size from the "Pack of" option above.
These gears are supplied with a plain bore. Securing method depends on your design: a set screw (grub screw) tapped into the hub is the most common approach for light-to-medium torque. For higher torque or reversing loads, a keyed shaft and matching keyway broached into the bore is recommended. Confirm hub dimensions and wall thickness before broaching.
