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When your motor drive slips, strips, or simply can't handle the load, the culprit is almost always an undersized or poorly machined gear. Whether you're a robotics builder, a CNC hobbyist, or a maker tackling a custom gearbox, these 45# steel Mod 1.5 spur gears give you the tooth count precision and material toughness to keep your drivetrain running without compromise.
Each gear is CNC-machined from 45# medium-carbon steel, delivering a solid balance of hardness and machinability. The module (pitch) is 1.5, with tooth counts ranging from 12T to 60T — corresponding to pitch circle diameters of approximately 18 mm (0.71 in) for 12T up to 90 mm (3.54 in) for 60T. Bore diameter varies by tooth count; see variant options for exact bore specs. Gear face width is typically 10–15 mm (0.39–0.59 in).
These Mod 1.5 pinion gears are well-suited for DC motor output shafts in small robotic arms, conveyor prototypes, and electric cart drives; for CNC router Z-axis rack-and-pinion setups requiring a compact steel pinion; and for DIY winch or lifting mechanisms where a reliable metal gear-to-gear mesh is critical.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Module (Pitch) | 1.5 |
| Tooth Count (T) | 12T – 60T (see variant options) |
| Pressure Angle | 20° |
| Pitch Circle Diameter | 18 mm – 90 mm (0.71 in – 3.54 in), varies by tooth count |
| Face Width | Typically 10–15 mm (0.39–0.59 in) |
| Bore Diameter | See variant options |
| Surface Finish | Natural steel with light oxide treatment |
| Pack Quantity | 1 piece per order (multi-pack options available) |
| Compatible Module | Mod 1.5 gear systems only |
Your gear ratio determines the tooth count pairing. Divide the driven gear teeth by the driving gear teeth to get the reduction ratio. For example, pairing a 12T pinion with a 36T gear gives a 3:1 reduction. Start with your required output speed and torque, then work backwards from your motor's RPM and torque curve to select the appropriate tooth counts.
Bore diameter varies by tooth count and is listed in the variant options on this page. If you need a specific bore size that differs from the standard, the 45# steel material is machinable — a local machine shop can enlarge the bore, add a keyway, or tap set-screw holes to match your motor shaft.
45# steel has a natural oxide surface treatment that provides basic protection against surface rust in dry, indoor environments. For outdoor use, high-humidity workshops, or applications involving water or cutting fluids, we recommend applying a light machine oil, grease, or a zinc-based spray coating after installation to extend service life.
Yes — any gear with a Module of 1.5 and a 20° pressure angle will mesh correctly with these steel gears, regardless of material. However, when pairing steel with softer materials like POM plastic or aluminum, the softer gear will wear faster. For long-term durability, steel-to-steel pairing is recommended in high-load applications.
Yes, these are designed as pinion gears for motor output shafts. Check the bore diameter in the variant options against your motor shaft diameter before ordering. If the bore is slightly larger than your shaft, a set-screw or shaft collar can secure the gear. If the bore is smaller, the gear can be bored out by a machinist.
The module number defines the tooth size — a higher module means larger, stronger teeth with a coarser pitch. Mod 1.5 sits between the fine-pitch Mod 1 (common in small RC and hobby applications) and the heavier-duty Mod 2 (used in larger industrial drives). Mod 1.5 gears cannot mesh with Mod 1 or Mod 2 gears — the module must match exactly across all mating gears in your system.
Torque capacity depends on tooth count, face width, and operating speed. As a conservative guideline for Mod 1.5 steel spur gears at moderate speeds (under 500 RPM), smaller tooth counts (12T–20T) are typically used in lighter-duty motor pinion roles, while larger tooth counts (40T–60T) can handle proportionally higher torque as the driven gear in a reduction pair. For critical load calculations, consult a gear design reference using the Lewis equation with the actual face width and material yield strength of 45# steel (approximately 600 MPa tensile).
