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When your motion system demands consistent torque transfer and dimensional accuracy, undersized or poorly machined gears become the weakest link. Engineers, robotics builders, and machine designers working with 1-module pitch drives need a spur gear that holds tolerance across the full tooth profile — not just at the bore. These 45# carbon steel keyway bore spur gears are machined to meet that standard, available in a wide tooth range from 40 to 150 teeth to cover the majority of 1-module drive configurations.
Each gear is manufactured from 45# medium-carbon steel, a structural grade known for its balance of machinability and tensile strength. The keyway bore design accommodates standard parallel keys, with inner hole diameters ranging from 8 mm (0.31 in) to 30 mm (1.18 in) and keyway dimensions from 3×1.4 mm up to 8×3.3 mm depending on bore size. Outer diameter scales with tooth count — from approximately 42 mm (1.65 in) for 40-tooth variants up to approximately 152 mm (5.98 in) for 150-tooth variants, all at 1-module pitch (module = 1 mm/tooth).
Typical use cases include CNC router axis drives and lead-screw reduction stages, robotic arm joint gearboxes requiring precise angular positioning, industrial conveyor and indexing table drive trains, and DIY automation projects where a keyed shaft connection is required for reliable torque transmission without set-screw slip.
Medium-carbon steel provides a tensile strength typically in the 600–800 MPa range, resisting deformation under sustained radial and tangential tooth loads in continuous-duty drive applications.
Available from 40 to 150 teeth in a single product listing, enabling gear ratio design across a broad range without sourcing from multiple suppliers.
Parallel keyway slots eliminate rotational slip under load — a critical advantage over set-screw-only hubs in reversing or high-torque drive cycles.
Inner hole options from 8 mm to 30 mm with matched keyway dimensions (3×1.4 mm through 8×3.3 mm) accommodate a wide range of standard shaft sizes.
Module 1 tooth geometry ensures correct mesh with any M1-rated mating gear or rack, maintaining consistent center distance and backlash within standard tolerance bands.
Suited for CNC machines, robotic joints, conveyor indexers, 3D printer extruder drives, and general-purpose industrial automation where a keyed shaft interface is specified.
| Module | 1 (M1) |
|---|---|
| Material | 45# Carbon Steel |
| Tooth Count | 40 – 150 teeth (see variant options) |
| Pressure Angle | 20° (standard) |
| Bore Type | Keyway bore (parallel key) |
| Inner Hole Diameter | 8 mm – 30 mm (see variant options) |
| Keyway Dimensions | 3×1.4 mm / 4×1.8 mm / 5×2.3 mm / 6×2.8 mm / 8×3.3 mm (matched to bore) |
| Outer Diameter (approx.) | (Teeth + 2) × 1 mm — see variant options |
| Face Width | See variant options |
| Surface Finish | See variant options |
| Quantity per Order | 1 piece |
Gear ratio is determined by dividing the driven gear tooth count by the driving gear tooth count. For example, a 40-tooth pinion driving an 80-tooth gear produces a 2:1 reduction. Calculate your required ratio first, then select the tooth count pair that achieves it while fitting within your center distance constraint. Center distance = (T1 + T2) / 2 × Module = (T1 + T2) / 2 mm for M1 gears.
Match the inner hole diameter to your shaft diameter. The keyway dimensions are fixed per bore size: 8–10 mm bores use a 3×1.4 mm key, 10–12 mm bores use 4×1.8 mm, 14–20 mm bores use 5×2.3 mm, and 22–30 mm bores use 6×2.8 mm or 8×3.3 mm. Verify the keyway spec in the variant name before ordering and confirm it matches your shaft's key slot.
45# carbon steel has a typical tensile strength of 600–800 MPa and yield strength around 355 MPa. Actual load capacity depends on tooth count, face width, operating speed, lubrication, and duty cycle. For precise load ratings, apply standard gear strength calculations (AGMA or ISO 6336) using the gear's geometry and your operating conditions. Contact us if you need application-specific guidance.
45# carbon steel has limited inherent corrosion resistance. For outdoor, humid, or washdown environments, apply a suitable surface treatment such as zinc plating, black oxide, or grease lubrication to protect the tooth surfaces and bore. For highly corrosive environments, consider stainless steel or plastic gear alternatives.
Yes — any M1 (module 1) spur gear with a 20° pressure angle will mesh correctly with a mating M1 rack or pinion of the same pressure angle. Confirm the pressure angle of your existing components before ordering. Mixed-module or mixed-pressure-angle gears will not mesh correctly and can cause rapid wear or tooth failure.
Both variants have the same 12 mm bore diameter but different keyway slot dimensions. The 4×1.8 mm keyway uses a narrower, shallower key suited to lighter-duty shafts, while the 5×2.3 mm keyway accommodates a wider, deeper key for higher torque transmission. Select the variant whose keyway matches the key slot already cut on your shaft, or specify the keyway when having your shaft machined.
The bore and keyway are pre-machined to the dimensions listed in the variant name. No additional boring or broaching is required if your shaft matches the listed bore diameter and keyway size. If you need a non-standard bore or keyway, the gear can be re-bored by a local machine shop after purchase.
