0.5 Mod 48 Teeth Spur Gears Transmission Gear With Step Motor Gears 45# Steel

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0.5 Mod 48 Teeth Spur Gears Transmission Gear With Step Motor Gears 45# Steel

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By HomeDIYer®

Size: 0.5M 48T, Bore 6mm

Packing Quantity: 1 pcs

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$13.30 USD

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In stock (500 units), ready to be shipped

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0.5 Mod 48-Tooth Spur Gear — Reliable 45# Steel for Stepper Motor Transmission

When a worn or incorrectly sized gear causes your CNC machine, 3D printer, or robotic actuator to lose accuracy, every subsequent operation compounds the error. Makers, automation engineers, and small-workshop builders who need a dependable 0.5 module 48-tooth spur gear will find this part machined to the tolerances their stepper motor drivetrains require.

Each gear is produced from 45# medium-carbon steel, delivering a practical balance of surface hardness and core toughness for repetitive meshing under moderate loads. The pitch diameter is 24 mm (≈ 0.94 in), with an outside diameter of approximately 25 mm (≈ 0.98 in) and a face width typically in the 5–8 mm (≈ 0.20–0.31 in) range. Bore options cover 6 mm, 8 mm, 10 mm, and 12 mm for plain round bores, plus keyed variants with 3×1.4 mm and 4×1.8 mm keyways for positive, slip-free shaft engagement.

Typical use cases include: swapping out drive gears on NEMA 17/23 stepper motor assemblies in desktop CNC routers and laser cutters; constructing compact gear-reduction stages in robotics and pick-and-place systems; and building multi-axis automation rigs where a consistent 0.5-module tooth pitch must be maintained across the entire drivetrain.

⚙️ Compatibility: Designed for 0.5 module gear systems. Meshes with any 0.5 Mod mating gear, rack, or pinion sharing a standard 20° pressure angle involute profile. Plain bore sizes (6–12 mm) fit common NEMA-frame stepper motor shafts. Keyed variants require a matching keyway on the shaft.

✅ Key Features of These 0.5 Mod 48-Tooth Spur Gears

🔩 45# Steel Construction

Medium-carbon steel provides the surface hardness needed for sustained meshing loads while remaining machinable for secondary bore adjustments if your application demands it.

📐 0.5 Module, 48 Teeth

Standard 0.5 Mod tooth profile ensures accurate, low-backlash meshing with any compatible 0.5 Mod rack, pinion, or mating gear in your drivetrain.

🎯 Multiple Bore Sizes

Plain round bores from 6 mm to 12 mm cover the most common NEMA 17 and NEMA 23 stepper motor shaft diameters for a direct, secure fit.

🔑 Keyed Bore Variants Available

Options with 3×1.4 mm and 4×1.8 mm keyways lock the gear to the shaft mechanically, eliminating rotational slip under torque reversals or sustained loads.

📦 Flexible Pack Quantities

Available in packs of 1 to 10 pieces so you can order exactly what a prototype build or a small production run requires without over-stocking.

🏭 Stepper Motor Ready

Bore tolerances and tooth geometry are matched to the shaft specifications of common NEMA-frame stepper motors used in CNC, 3D printing, and robotics platforms.

📐 Technical Specifications — 0.5 Mod Spur Gear

Module	0.5
Number of Teeth	48
Pitch Diameter	24 mm (≈ 0.94 in)
Outside Diameter	≈ 25 mm (≈ 0.98 in)
Face Width	See variant options
Bore Diameter	6 / 8 / 10 / 12 mm (see variant options)
Keyway	3×1.4 mm or 4×1.8 mm (keyed variants only)
Material	45# Medium-Carbon Steel
Tooth Profile	Standard involute, 20° pressure angle
Finish	See variant options
Packing Quantity	1 / 2 / 3 / 4 / 5 / 8 / 10 pcs (see variant options)
Weight (per piece)	See variant options

❓ Frequently Asked Questions

How do I choose the right bore size for my stepper motor shaft?

Measure your motor shaft diameter with a caliper before ordering. NEMA 17 motors typically use a 5 mm shaft — the 6 mm plain bore with a set screw is the closest standard fit. NEMA 23 motors commonly use an 8 mm or 6.35 mm shaft. Larger motors may use 10–12 mm shafts. If your shaft has a flat or keyway, select the matching keyed bore variant for a secure, slip-free connection.

What load can a 0.5 Mod 48-tooth gear in 45# steel handle?

45# medium-carbon steel has a tensile strength typically in the 600–800 MPa range after standard heat treatment. At 0.5 module, these gears are suited to light-to-moderate torque applications — desktop CNC axis drives, 3D printer extruder gearboxes, and small robotic joints. For heavy industrial or high-cycle loads, a larger module or alloy-steel gear is more appropriate.

Are these gears corrosion-resistant?

45# carbon steel is not inherently stainless. In dry indoor environments typical of desktop CNC and 3D printing setups, the material performs reliably without additional treatment. If your application involves moisture, coolant mist, or outdoor exposure, apply a light coat of machine oil or grease to the tooth faces to prevent surface oxidation.

Will a 48-tooth gear mesh with my existing 0.5 Mod rack or pinion?

Yes — provided your rack, pinion, or mating gear is also 0.5 module with a standard 20° pressure angle involute profile. Module and pressure angle must match between mating components; tooth count only determines the gear ratio, not mechanical compatibility.

What is the difference between a plain bore and a keyed bore variant?

A plain bore transmits torque via a set screw pressing against the shaft flat, or through an interference fit. A keyed bore has a machined slot that accepts a matching key on the shaft, creating a positive mechanical lock. Keyed variants are recommended for higher torque, reversing loads, or any application where set-screw loosening over time is a concern.

Can I order one piece first to verify fitment before buying a larger pack?

Yes. Every bore size and variant is available as a 1-piece pack, allowing you to confirm shaft fit, tooth mesh, and assembly clearance before committing to a multi-piece order.

How does the 48-tooth count affect my gear ratio compared to other tooth counts?

Gear ratio equals the driven gear tooth count divided by the driving gear tooth count. Pairing this 48-tooth gear with an 8-tooth pinion on your motor shaft gives a 6:1 reduction, multiplying output torque by 6 while reducing speed by the same factor. Compared to a 50-tooth gear with the same pinion, the 48-tooth gear produces a slightly lower reduction ratio (6:1 vs 6.25:1), which may suit applications requiring marginally higher output speed.

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