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When your CNC router, 3D printer, or automated motion system demands consistent torque transfer without slippage or premature wear, the right gear specification makes all the difference. Engineers, makers, and machine builders who rely on Module 4 drive trains need a spur gear that holds tight tolerances across every tooth — whether they're running a desktop router or a full-scale fabrication rig.
These 4 Mod steel spur gears feature a uniform face width (thickness) of 40mm (~1.57 inches) and are available in tooth counts ranging from 12 to 50 teeth. The pitch diameter scales proportionally with tooth count: a 12-tooth gear measures approximately 48mm (~1.89 in) pitch diameter, while a 50-tooth gear reaches approximately 200mm (~7.87 in). Each gear is machined from steel for strength and dimensional stability under load.
Typical use cases include CNC rack-and-pinion drive systems for gantry axes, rotary indexing tables requiring precise angular positioning, 3D printer extruder and Z-axis drive assemblies, and custom robotics or automation builds where Module 4 gearing is specified. The wide tooth-count selection makes it straightforward to match your required gear ratio without custom machining.
Conforms to the international Module 4 gear standard, ensuring direct interchangeability with Mod 4 racks, pinions, and mating gears across CNC and automation platforms.
A generous 40mm (1.57 in) tooth face width distributes load evenly across the gear mesh, reducing contact stress and extending service life under continuous or intermittent duty cycles.
Choose from 12 through 50 teeth (12–50T) to dial in your exact gear ratio. Covers a wide range of speed-reduction and torque-multiplication requirements without custom fabrication.
Machined from steel for the structural rigidity needed in CNC, robotics, and 3D printing drive trains. Resists deformation under the cyclic loads typical of automated motion systems.
Involute tooth geometry is machined to consistent tolerances, delivering smooth mesh engagement, reduced backlash, and quieter operation compared to cast or sintered alternatives.
Suited for CNC gantry drives, rotary tables, extruder assemblies, conveyor drives, and custom automation builds wherever a Mod 4 spur gear is specified.
| Module (Mod) | 4 |
|---|---|
| Number of Teeth | 12 / 13 / 14 / 15 / 16 / 17 / 18 / 19 / 20 / 21 / 22 / 23 / 24 / 25 / 26 / 27 / 28 / 29 / 30 / 31 / 32 / 33 / 34 / 35 / 36 / 37 / 38 / 39 / 40 / 41 / 42 / 43 / 44 / 45 / 46 / 48 / 50 |
| Face Width (Thickness) | 40mm (1.57 in) |
| Pitch Diameter | Module × Teeth (e.g., 4 × 12 = 48mm; 4 × 50 = 200mm) |
| Pressure Angle | 20° (standard involute) |
| Material | Steel |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | See variant options |
| Gear Type | Spur Gear (straight tooth) |
| Packing Quantity | 1 Piece per order |
| Application | CNC machines, 3D printers, robotics, automation drives |
Your gear ratio is determined by dividing the tooth count of the driven gear by the tooth count of the driving gear. For example, pairing a 12-tooth pinion with a 36-tooth gear gives a 3:1 reduction. Select the tooth count that achieves your target speed or torque ratio. If you are replacing an existing gear, match the tooth count exactly to maintain the original ratio.
Module (Mod) is the metric standard for gear tooth size, defined as the pitch diameter divided by the number of teeth. Module 4 gears have a tooth pitch of 4mm per tooth. Two gears must share the same module to mesh correctly. If your existing rack, pinion, or mating gear is marked "M4" or "Mod 4", these gears are directly compatible.
The bore diameter varies by tooth count and is listed in the variant details. If you need a specific bore size or keyway to match your shaft, please contact us before ordering so we can confirm availability or discuss machining options.
These gears are machined from steel, which provides the load-bearing capacity needed for CNC gantry drives, rotary tables, and similar applications. The 40mm face width further distributes tooth load. For very high-torque or shock-load environments, verify the gear's rated torque capacity against your application requirements before installation.
Steel spur gears operating under load benefit from periodic lubrication to reduce friction and wear. A light machine oil or gear grease applied to the tooth faces is recommended for most CNC and automation applications. Lubrication interval depends on duty cycle, speed, and load — consult your machine's maintenance guidelines for specifics.
These gears use the standard 20° pressure angle, which is the most widely adopted specification in modern CNC and industrial gear systems. For two gears to mesh correctly, they must share both the same module and the same pressure angle. If your existing gears use a 14.5° pressure angle (an older standard), these gears will not be compatible.
Yes. These Module 4 spur gears are designed to mesh with Module 4 racks for rack-and-pinion linear motion systems, which are commonly used on CNC router X/Y axes and gantry systems. Ensure the rack face width is compatible with the 40mm gear thickness for full tooth engagement.
