0.5 Mod 50 Teeth Transmission Gears Spur Gear With Step Motor Gears 45# Steel

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0.5 Mod 50 Teeth Transmission Gears Spur Gear With Step Motor Gears 45# Steel

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By HomeDIYer®

Size: 0.5M 50T, Bore 6mm

Packing Quantity: 1 pcs

Price:

$13.59 USD

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In stock (500 units), ready to be shipped

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0.5 Module 50-Tooth Spur Gear — Precision Steel Drive for Stepper & Servo Motors

When your CNC router, 3D printer, or robotic arm demands repeatable, low-backlash motion, a poorly fitted gear becomes the weakest link in the entire drivetrain. This 0.5 Mod 50 Teeth Transmission Spur Gear is engineered for makers, automation engineers, and small-workshop builders who need a reliable, drop-in drive component without custom machining.

Each gear is machined from 45# medium-carbon steel, offering a balanced combination of hardness and toughness suited to moderate-load transmission applications. The module is 0.5 with 50 teeth, giving an outer diameter of approximately 26 mm (≈1.02 in). Bore options range from 6 mm to 14 mm (plain bore) and include step-bore configurations (e.g., 8/3×1.4 mm, 10/3×1.4 mm, 10/4×1.8 mm, 12/4×1.8 mm) designed to seat directly on standard stepper motor shafts with a flat or keyway.

Typical use cases include: pairing with NEMA 17 or NEMA 23 stepper motors in CNC gantry systems for precise rack-and-pinion or gear-train positioning; building compact gear-reduction stages in robotic joints and actuator assemblies; and replacing worn drive gears in small automated conveyor or indexing fixtures where a 0.5-module pitch is already established.

⚙️ Compatibility: Designed for 0.5-module gear systems. Mates with any 0.5 Mod rack, pinion, or mating gear. Bore sizes suit NEMA 17 (5 mm shaft — use 6 mm bore with set screw), NEMA 23 (6.35 mm shaft), and common stepper/servo shaft diameters up to 14 mm. Step-bore variants fit shafts with a D-flat or keyway slot.

✅ Key Features of These 0.5 Mod 50-Tooth Spur Gears

🔩 45# Steel Construction

Medium-carbon steel provides the hardness needed for consistent tooth engagement under cyclic loads, while remaining machinable for secondary bore modifications if required.

📐 0.5 Module, 50 Teeth

Standard 0.5 Mod pitch ensures direct interchangeability with any 0.5-module rack or mating gear. 50 teeth yield an OD of ~26 mm (≈1.02 in), keeping the assembly compact.

🎯 Multiple Bore Options

Choose from plain bores (6, 6.35, 8, 10, 12, 14 mm) or step-bore configurations sized for common stepper motor shaft diameters — no adapter sleeve needed in most builds.

⚡ Step-Bore Variants for Motor Shafts

Step-bore options (8/3×1.4 mm, 10/3×1.4 mm, 10/4×1.8 mm, 12/4×1.8 mm) are machined to accept a D-flat or keyway, providing positive torque transfer without slipping under load.

📦 Flexible Pack Quantities

Available in packs of 1, 2, 3, 4, 5, 8, or 10 pieces — order exactly what your project needs, or stock up for multi-axis builds and spare-parts inventory.

🔄 Broad Application Compatibility

Suited for CNC routers, 3D printer extruder drives, robotic arm joints, indexing tables, and any DIY automation project running a 0.5-module gear train.

📐 Technical Specifications — 0.5 Mod Spur Gear

Module	0.5
Number of Teeth	50
Outer Diameter (OD)	~26 mm (~1.02 in)
Pitch Diameter	25 mm (0.98 in)
Face Width	See variant options
Bore Diameter	6 / 6.35 / 8 / 10 / 12 / 14 mm (plain); 8/3×1.4, 10/3×1.4, 10/4×1.8, 12/4×1.8 mm (step bore)
Material	45# Medium-Carbon Steel
Pressure Angle	20°
Gear Type	Spur Gear (straight tooth)
Finish	See variant options
Packing Quantity	1 / 2 / 3 / 4 / 5 / 8 / 10 pcs (select above)
Compatible Module	0.5 Mod gear systems

❓ Frequently Asked Questions

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

Match the bore to your motor shaft diameter. NEMA 17 motors typically use a 5 mm shaft — select the 6 mm bore and secure with a set screw or locking collar. NEMA 23 motors commonly use a 6.35 mm (1/4 in) shaft, so choose the 6.35 mm bore option. For motors with a D-flat or keyway, select the corresponding step-bore variant (e.g., 8/3×1.4 mm means an 8 mm shaft with a 3 mm wide × 1.4 mm deep keyway slot).

What does the step-bore specification (e.g., 8/3×1.4mm) mean?

The step-bore notation describes a two-diameter bore: the first number is the main shaft diameter (e.g., 8 mm), and the second pair (3×1.4 mm) is the width × depth of the keyway or D-flat relief machined into the bore wall. This allows the gear to lock onto a keyed or D-shaft without rotating under torque.

Is 45# steel strong enough for my application?

45# medium-carbon steel (roughly equivalent to AISI 1045) offers a tensile strength of approximately 600–800 MPa in its normalized state, making it well-suited for moderate-load, low-to-medium speed gear drives such as CNC positioning axes, robotic joints, and small conveyor drives. For very high-speed or heavy-shock-load applications, consider whether a hardened or alloy steel gear would be more appropriate.

Will this gear rust or corrode?

Carbon steel is susceptible to surface oxidation in humid environments. For indoor, dry-environment use (typical of CNC machines and 3D printers), the bare steel surface is generally acceptable with light lubrication. If your application involves moisture exposure, apply a thin coat of machine oil or grease to the tooth faces and bore, or consider a corrosion-resistant coating after installation.

What mating gear or rack should I use with this 0.5 Mod 50T gear?

Any gear or rack with a 0.5 module and a 20° pressure angle will mesh correctly with this gear. The center distance between two meshing 0.5 Mod gears equals (T1 + T2) × 0.5 / 2, where T1 and T2 are the tooth counts. For example, pairing this 50T gear with a 20T pinion gives a center distance of (50 + 20) × 0.5 / 2 = 17.5 mm.

How many pieces should I order for a multi-axis CNC build?

A standard 3-axis CNC router or gantry system typically requires one drive gear per axis, so a 3-piece pack covers a full machine. Many builders order an extra piece as a spare. For a 4- or 5-axis machine, the 5-piece or 8-piece pack offers the best per-unit value. Check the packing quantity selector above to compare pricing across pack sizes.

Can I modify the bore size myself after purchase?

Yes. 45# steel is machinable on a lathe or with a drill press and reamer. You can bore out a smaller bore to a larger diameter, or add a keyway with a broach. However, do not reduce the bore below the listed size, and ensure the remaining wall thickness is sufficient for your torque requirements. If you are unsure, select the closest bore size to your shaft and consult a machinist.

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