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When a slipping or undersized gear stalls your CNC router, robotics arm, or automation rig mid-cycle, the cost is more than downtime — it's lost precision and rework. Engineers, makers, and small-batch manufacturers who need a dependable, drop-in spur pinion gear turn to Module 2.5 steel gears that hold tight tolerances run after run.
These spur pinion gears are machined from #45 carbon steel, a medium-carbon alloy known for its balanced hardness and toughness. The module is 2.5 (pitch = 2.5 mm per tooth), with tooth counts ranging from 10T to 30T across the available variants. Bore diameter and hub dimensions vary by tooth count — see variant options for exact figures. Each gear features a standard involute tooth profile for smooth, low-noise meshing.
Typical use cases include CNC gantry drives requiring precise rack-and-pinion positioning, robotic joint actuators where compact gear sets transmit torque in tight spaces, and industrial conveyor or indexing systems that demand consistent gear mesh under cyclic loads. Long-tail applications such as "module 2.5 replacement pinion gear for CNC router" and "45 steel spur gear 20 tooth automation" are well served by this range.
Machined from #45 medium-carbon steel for a strong balance of surface hardness and core toughness, resisting wear under sustained mesh loads.
Standard involute geometry ensures smooth, low-noise engagement and full interchangeability with any Module 2.5 mating gear or rack.
Fourteen tooth-count options (10T, 11T, 12T, 13T, 14T, 15T, 16T, 18T, 20T, 23T, 24T, 25T, 28T, 30T) let you dial in the exact gear ratio your drive system needs.
Each pinion is turned and hobbed to maintain repeatable tooth spacing and runout, keeping your transmission backlash predictable across the full tooth-count range.
Available in 1, 2, 3, 4, or 5-piece packs per variant — order spares alongside your primary gear to minimize future downtime on production builds.
Suited for CNC routers, 3D printer extruder drives, robotic actuators, conveyor indexers, and any motion-control system calling for a Module 2.5 steel pinion.
| Module | 2.5 |
|---|---|
| Tooth Count (T) | 10T, 11T, 12T, 13T, 14T, 15T, 16T, 18T, 20T, 23T, 24T, 25T, 28T, 30T |
| Material | #45 Carbon Steel |
| Tooth Profile | Standard Involute |
| Pressure Angle | 20° |
| Pitch Diameter | See variant options (Module × Teeth) |
| Bore Diameter | See variant options |
| Hub / Face Width | See variant options |
| Surface Finish | Machined, natural steel |
| Quantity per Pack | 1, 2, 3, 4, or 5 Pcs (select variant) |
Your gear ratio is determined by dividing the tooth count of the driven gear by the tooth count of the driving pinion. For example, pairing a 10T pinion with a 30T gear gives a 3:1 reduction. Select a tooth count that achieves your target ratio while keeping the center distance within your mechanical envelope. The pitch diameter equals Module × Teeth (e.g., 2.5 × 20T = 50 mm PD).
#45 carbon steel (roughly equivalent to AISI 1045) has a tensile strength typically in the range of 600–800 MPa in the normalized condition. It offers good machinability and can be further hardened by heat treatment if your application demands higher surface hardness. For most CNC and light-industrial automation loads, the as-machined condition is sufficient.
#45 carbon steel is not inherently stainless. In humid or wet environments, apply a light machine oil or anti-corrosion coating after installation. For outdoor or washdown applications, consider pairing with a protective grease or sourcing a stainless-steel alternative.
Yes — any gear or rack with a Module 2.5 standard involute profile and a 20° pressure angle will mesh correctly with these pinions. Confirm the module and pressure angle on your mating component before ordering. Module is not interchangeable with Diametral Pitch (DP) imperial gears.
Bore diameter varies by tooth count. Please refer to the variant detail page or contact us to confirm the bore size for your selected tooth count before ordering. A bore that is too small can be enlarged by a machinist; a bore that is too large will require a bushing or keyway insert.
Absolutely. Module 2.5 steel pinion gears are commonly used in extruder drives, Z-axis lead-screw couplings, and robotic joint actuators where plastic gears would wear prematurely. The smaller tooth counts (10T–14T) are popular for compact drive stages, while larger counts (20T–30T) suit lower-ratio or higher-torque stages.
Ordering 2–5 pieces at once reduces per-unit cost and ensures you have on-hand spares for maintenance or prototype iterations. For production builds or machines running continuous duty cycles, keeping a spare pinion on the shelf eliminates lead-time delays when a gear eventually needs replacement.
