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When your motion-control build demands consistent tooth engagement and repeatable torque transfer, an undersized or poorly machined gear becomes the weakest link in the chain. Engineers, CNC hobbyists, and robotics makers who need a reliable 1 Mod spur gear across a wide tooth-count range will find this stepped-bore series covers the most common shaft sizes without custom machining.
Each gear is machined from 45# medium-carbon steel — a material known for its balanced hardness and toughness after heat treatment. The module is 1M (1 mm per tooth pitch), with tooth counts spanning 31T to 125T and stepped bore options from 6 mm (0.24 in) to 25 mm (0.98 in). Outer diameters scale proportionally from approximately 33 mm (1.30 in) for the 31T up to 127 mm (5.00 in) for the 125T.
Typical use cases include small-format CNC router Z-axis drives, 3D printer extruder gear trains, tabletop robotic arm joints, and DIY electric vehicle reduction stages — all applications where a 1 mod spur gear with stepped bore simplifies shaft-to-gear assembly without a press fit or custom keyway.
Medium-carbon steel provides the hardness needed for sustained mesh loads while remaining machinable for secondary bore modifications if required.
A single product family covers gear ratios from roughly 1:4 down to 1:1, reducing the number of SKUs you need to stock for a multi-stage gearbox.
Pre-machined bore diameters — 6, 8, 10, 12, 14, 15, and 25 mm — match the most common motor and shaft standards, eliminating custom boring for most builds.
Involute tooth geometry machined to Module 1 standard ensures smooth, low-noise meshing with any compliant 1M rack or mating gear across the full tooth-count range.
The integrated step hub provides a positive axial reference surface, simplifying gear positioning on the shaft and reducing assembly time in multi-gear arrangements.
Suited for CNC machines, robotic joints, 3D printer drive trains, conveyor systems, and DIY reduction gearboxes where a 1 mod spur gear with stepped bore is the standard choice.
| Module | 1M (1 mm/tooth) |
|---|---|
| Tooth Count | 31T, 32T, 34T, 35T, 36T, 37T, 38T, 39T, 40T, 42T, 45T, 50T, 55T, 60T, 70T, 80T, 100T, 120T, 125T |
| Bore Diameter | 6 mm / 8 mm / 10 mm / 12 mm / 14 mm / 15 mm / 25 mm (see variant options) |
| Outer Diameter (OD) | See variant options (scales with tooth count; approx. (T+2) × 1 mm) |
| Material | 45# Medium-Carbon Steel |
| Hub Style | Stepped hub |
| Tooth Profile | Involute, Module 1 |
| Pressure Angle | 20° |
| Face Width | See variant options |
| Surface Finish | See variant options |
| Quantity per Order | 1 piece |
Select your tooth count based on the gear ratio you need. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 31T with a 62T gear gives a 2:1 reduction. Use a higher tooth count on the output side for torque multiplication, or a lower count for speed increase.
Match the bore diameter to your shaft diameter exactly. Available bores are 6, 8, 10, 12, 14, 15, and 25 mm. If your shaft is metric, select the matching bore. For imperial shafts, convert first — for example, a 1/4" shaft is 6.35 mm, which is closest to the 6 mm bore (you may need a light reaming pass for a precise fit).
45# steel offers a tensile strength of approximately 600–800 MPa after heat treatment, making these gears suitable for moderate-to-high torque applications in CNC, robotics, and light industrial drives. Exact load ratings depend on tooth count, face width, speed, and lubrication. For critical load calculations, apply standard AGMA or ISO gear rating methods using the actual face width of your selected variant.
45# carbon steel has limited inherent corrosion resistance. For outdoor or humid environments, apply a light machine oil or grease to the tooth surfaces and bore. If corrosion resistance is a primary requirement, consider stainless steel or nylon gear alternatives for your application.
Yes — any gear or rack manufactured to the Module 1 standard with a 20° pressure angle will mesh correctly with these gears. Confirm that your existing components are labeled 1M or M1 before ordering. Gears of different modules (e.g., 0.8M or 1.5M) are not interchangeable.
The stepped hub is a raised cylindrical boss on the gear face that provides a positive axial stop when mounting the gear on a shaft. This makes it easier to position the gear at a precise location along the shaft without additional spacers, and it improves concentricity during assembly — particularly useful in multi-stage gearboxes and robotic joint assemblies.
Yes. The 1M module is a common standard in desktop CNC and 3D printer drive systems. The smaller tooth counts (31T–42T) are frequently used in extruder gear trains and Z-axis lead-screw drives, while larger counts (50T–125T) suit reduction stages in robotic arms and conveyor drives. Verify the bore matches your motor shaft and that the OD clears your enclosure before finalizing your selection.
