2 Modul 45# Steel Spur Gears Pinion Gear Thick 20mm 10 - 120 Teeth For 3D CNC

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2 Modul 45# Steel Spur Gears Pinion Gear Thick 20mm 10 - 120 Teeth For 3D CNC

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Material: 45# Steel

Modulus: 2 Modulus

Number of gear teeth & Amount: 10 Teeth & 1 PCS

Price:

$10.17 USD

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In stock (500 units), ready to be shipped

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2 Modulus 45# Steel Spur Gear — Thick 20mm Pinion for CNC, 3D Printing & Robotics

When your CNC router, 3D printer, or automation rig demands a spur gear that won't slip, strip, or flex under load, a lightweight plastic or low-grade metal gear becomes the weak link in your entire drivetrain. Engineers, makers, and small-batch manufacturers who need consistent torque transmission across a wide tooth-count range rely on a solid steel pinion that holds tolerance run after run.

These spur gears are machined from 45# medium-carbon steel — a structural steel known for its balanced hardness and machinability — with a uniform face width (thickness) of 20mm (~0.79 in). The module is 2 (Mod 2), meaning each tooth pitch diameter equals 2 × tooth count in millimeters. Bore diameter options range from plain round bores to keyway-fitted bores (see variant options), accommodating shaft diameters typically from 8mm to 30mm (~0.31–1.18 in). Tooth counts span 10 to 120 teeth, giving you a gear ratio range of 12:1 in a single product family.

Typical use cases include: CNC rack-and-pinion linear drives where a Mod 2 pinion meshes with a matching rack for precise X/Y axis travel; 3D printer extruder and Z-axis lead-screw drives requiring a compact, low-backlash steel pinion gear; and light industrial conveyor or rotary indexing systems where a 45# steel spur gear with keyway bore provides positive shaft engagement without set-screw slippage.

⚙️ Compatibility: Meshes with any Mod 2 spur gear, rack, or worm wheel. Verify bore diameter and keyway dimensions match your shaft before ordering.

✅ Key Features of These 2 Modulus 45# Steel Spur Gears

🔩 45# Medium-Carbon Steel Construction

Machined from 45# structural steel for reliable hardness, wear resistance, and dimensional stability under continuous rotational load — without the brittleness of hardened tool steel.

📐 Module 2 Tooth Profile

Standard Mod 2 involute tooth form ensures smooth meshing with any compatible Mod 2 counterpart — rack, pinion, or gear — with predictable backlash and load distribution.

📏 Uniform 20mm Face Width

A consistent 20mm (~0.79 in) tooth face width across all tooth counts provides stable contact area and even load sharing, reducing edge stress on smaller pinions.

🎯 Wide Tooth Count Range: 10–120 Teeth

Select from 10 to 120 teeth in a single product family, enabling gear ratios from 1:1 to 12:1 without switching module sizes or sourcing from multiple suppliers.

🔑 Plain Bore & Keyway Bore Options

Available with plain round bores for set-screw mounting or keyway-fitted bores (e.g., 20mm bore + 6mm keyway) for positive, slip-free shaft engagement in higher-torque applications.

🏭 CNC & 3D Printer Ready

Dimensionally consistent tooth profiles and bore concentricity make these gears a direct fit for CNC rack-and-pinion systems, 3D printer drive trains, and light industrial automation builds.

📐 Technical Specifications — Mod 2 Steel Spur Gear

Material	45# Medium-Carbon Steel
Module (Mod)	2
Face Width (Thickness)	20mm (~0.79 in)
Number of Teeth	10 – 120 Teeth (see variant options)
Bore Diameter	See variant options
Keyway	See variant options (plain bore or keyway)
Tooth Profile	Involute, 20° pressure angle
Pitch Diameter	Mod × Teeth (e.g., 2 × 20T = 40mm)
Surface Finish	Machined, natural steel
Quantity per Order	1 PCS

❓ Frequently Asked Questions

How do I choose the right tooth count for my application?

Determine your required gear ratio first: divide the driven gear teeth by the driving pinion teeth. For a CNC rack-and-pinion, the linear travel per revolution equals π × Mod × Teeth (e.g., a 20-tooth Mod 2 pinion gives ~125.7mm per revolution). Select the tooth count that achieves your target ratio or travel distance, then confirm the resulting pitch diameter fits within your housing clearance.

What is the difference between a plain bore and a keyway bore?

A plain bore relies on a set screw or press fit to secure the gear to the shaft — suitable for lighter loads and easy repositioning. A keyway bore uses a machined slot that accepts a key, creating a positive mechanical lock between gear and shaft. Keyway variants are recommended for higher-torque drives, reversing loads, or any application where set-screw slippage is a concern.

Will this gear mesh with my existing Mod 2 rack or gear?

Yes — as long as your existing rack or mating gear is also Module 2 with a standard 20° pressure angle involute profile, these gears will mesh correctly. Module (pitch) must match between meshing gears; mixing Mod 1.5 and Mod 2 components will result in incorrect tooth engagement and accelerated wear.

How strong is 45# steel compared to other gear materials?

45# steel (equivalent to C45 / SAE 1045) has a tensile strength of approximately 600–800 MPa in the normalized condition, making it significantly stronger than aluminum, brass, or engineering plastics. It is well-suited for moderate-load power transmission. For very high-cycle or high-shock applications, consider specifying heat-treated or case-hardened variants.

Does 45# steel rust, and how should I protect it?

Yes, 45# carbon steel will oxidize if exposed to moisture without protection. For indoor CNC and 3D printer environments, a light machine oil or grease applied to the tooth faces is sufficient. For outdoor or humid environments, consider a zinc-phosphate primer coat or periodic re-greasing. The natural machined finish is not corrosion-resistant on its own.

Can I use this gear in a 3D printer extruder or Z-axis drive?

Yes. Mod 2 steel spur gears are commonly used in 3D printer Z-axis lead-screw drives and extruder gear trains where plastic gears have worn out. Select a tooth count that matches your existing gear ratio, and choose a bore diameter that fits your motor shaft — with a keyway bore for stepper motors that use a flat-key shaft coupling.

What is the pitch diameter for a given tooth count?

For a Mod 2 gear, pitch diameter (PD) = Module × Number of Teeth. Examples: 10T → PD 20mm; 20T → PD 40mm; 40T → PD 80mm; 60T → PD 120mm; 100T → PD 200mm; 120T → PD 240mm. The outside diameter (OD) = PD + 2 × Module = PD + 4mm.

🛒 Select your tooth count and bore diameter above, then add to cart.