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

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

Name: 0.5 Mod 45 Teeth Spur Gears Transmission Gear With Step Motor Gears 45# Steel
Brand: HomeDIYer
Price: 12.73 USD
Availability: InStock

HomeDIYer

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By HomeDIYer®

Size: 0.5M 45T, Bore 6mm

Packing Quantity: 1 pcs

Price:

$12.73 USD

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In stock (500 units), ready to be shipped

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0.5 Mod 45-Tooth Spur Gear — Reliable Transmission for Stepper Motor Builds

When your DIY automation project demands precise, low-backlash power transfer, a mismatched or undersized gear becomes the weakest link in the entire drivetrain. Makers, robotics hobbyists, and small-workshop engineers who run NEMA-series stepper motors need a 0.5 module spur gear that fits cleanly, meshes accurately, and holds up under continuous duty — without sourcing from industrial distributors at industrial prices.

These 0.5 Mod 45-tooth spur gears are machined from 45# medium-carbon steel, delivering a solid balance of hardness and machinability. The module (pitch) is 0.5 mm, the tooth count is 45T, and bore options span 6 mm, 6.35 mm (1/4"), 8 mm, 10 mm, and 12 mm for standard round bores, plus stepped keyway bores of 8/3×1.4 mm, 10/3×1.4 mm, and 10/4×1.8 mm for keyed shaft applications. The outer diameter is approximately 23.5 mm (0.93 in) and the face width is typically 5–8 mm (0.20–0.31 in) depending on the variant.

Typical use cases include 0.5 mod gear trains for NEMA 17 and NEMA 23 stepper motor output shafts, compact robotic arm joint drives requiring a 45-tooth spur gear ratio stage, and small CNC or 3D-printer extruder transmission assemblies where a module 0.5 steel gear ensures long-term dimensional stability.

⚙️ Compatible with all standard 0.5 module gear systems. Meshes with any 0.5 Mod mating gear regardless of tooth count. Bore sizes suit NEMA 17 (5 mm shaft), NEMA 23 (6.35 mm shaft), and common metric motor shafts.

✅ Key Features of These 0.5 Mod 45-Tooth Spur Gears

🔩 45# Medium-Carbon Steel Construction — Machined from 45# steel for a reliable combination of surface hardness and core toughness, resisting wear under sustained meshing loads in automation and robotics applications.
📐 Precision 0.5 Module, 45-Tooth Profile — Standard involute tooth geometry ensures smooth, low-noise engagement with any mating 0.5 Mod gear. Consistent pitch across the full tooth face minimizes vibration in high-cycle stepper motor drives.
🎯 Multiple Bore Options for Direct Shaft Fit — Choose from round bores (6 mm, 6.35 mm, 8 mm, 10 mm, 12 mm) or stepped keyway bores (8/3×1.4 mm, 10/3×1.4 mm, 10/4×1.8 mm) to match your motor shaft without custom machining.
📦 Flexible Pack Quantities — 1 to 10 Pieces — Available in packs of 1, 2, 3, 4, 5, 8, or 10 pieces so you can stock exactly what your project or workshop requires, with per-unit cost savings at higher quantities.
🔄 Compact OD for Space-Constrained Builds — The ~23.5 mm outer diameter keeps your gear stage tight, making these 45T spur gears ideal for compact robotic joints, extruder drives, and miniature CNC transmission stages.
🛠️ Drop-In Compatibility with Standard 0.5 Mod Systems — Interchangeable with any commercially available 0.5 module gear set. No special tooling required for installation on smooth or keyed shafts within the listed bore range.

📐 Technical Specifications — 0.5 Mod Spur Gear

Module (Pitch)	0.5 mm
Number of Teeth	45T
Outer Diameter (OD)	Approx. 23.5 mm (0.93 in)
Face Width	Typically 5–8 mm (0.20–0.31 in)
Bore Options	6 mm / 6.35 mm / 8 mm / 10 mm / 12 mm (round); 8/3×1.4 mm, 10/3×1.4 mm, 10/4×1.8 mm (keyway)
Material	45# Medium-Carbon Steel
Tooth Profile	Standard Involute
Pressure Angle	20°
Gear Type	Spur Gear
Finish	See variant options
Pack Quantity	1 / 2 / 3 / 4 / 5 / 8 / 10 pcs (select above)
Weight (per piece)	See variant options

❓ Frequently Asked Questions

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

Match the bore to your motor's output shaft diameter. NEMA 17 motors typically use a 5 mm shaft — select the 6 mm bore and use a set screw or locking collar, or choose the closest bore and bore it out if needed. NEMA 23 motors commonly use a 6.35 mm (1/4") shaft, so the 6.35 mm bore variant is a direct fit. For 8 mm, 10 mm, or 12 mm shafts, select the matching round bore. If your shaft has a keyway, choose the corresponding stepped keyway bore variant (e.g., 8/3×1.4 mm for an 8 mm shaft with a 3×1.4 mm key).

What is the outer diameter and pitch diameter of this 0.5 Mod 45T gear?

For a 0.5 module, 45-tooth spur gear, the pitch diameter = Module × Teeth = 0.5 × 45 = 22.5 mm. The outer (tip) diameter = (Teeth + 2) × Module = 47 × 0.5 = 23.5 mm. These are standard involute gear formulas and apply to all variants in this listing.

Is 45# steel strong enough for continuous-duty stepper motor applications?

Yes. 45# medium-carbon steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in its normalized state and can be heat-treated for higher surface hardness. For typical stepper motor torque outputs in the 0.1–3 Nm range, these gears provide adequate strength and wear resistance. For very high-cycle or high-torque applications, consider whether additional surface treatment (e.g., case hardening) is appropriate for your specific load profile.

Will this gear mesh correctly with other 0.5 module gears I already have?

Yes. All standard 0.5 module involute spur gears with a 20° pressure angle are interchangeable regardless of tooth count or manufacturer, as long as the module matches. This gear will mesh correctly with any 0.5 Mod mating gear — whether it has 10, 20, 30, or more teeth — provided the center distance is set correctly for the combined pitch radii.

Does 45# steel resist corrosion, and can I use these gears in humid environments?

45# carbon steel has limited inherent corrosion resistance compared to stainless steel. For humid or wet environments, we recommend applying a light machine oil or grease to the gear teeth and bore after installation. If long-term corrosion resistance is critical, consider a zinc-plated or stainless-steel alternative. For typical indoor workshop or enclosed robotic enclosure use, standard lubrication maintenance is sufficient.

What pack size should I order for a multi-stage gear train project?

For a single-stage drive (one gear pair), order at least 2 pcs. For a two-stage compound gear train, 4 pcs is a common starting point. The 5-pack and 10-pack options offer better per-unit value and provide spares for prototyping or future repairs. If you are building multiple identical assemblies, the 8-pack or 10-pack minimizes reorder frequency.

Can I use the keyway bore variants without a key — just with a set screw?

The keyway bore variants (e.g., 8/3×1.4 mm) are designed for use with a matching key for positive torque transmission. While a set screw alone can work for very low-torque or positioning applications, it is not recommended for sustained or reversing loads, as the set screw may loosen over time. For best results, use the keyway with a properly fitted key and a set screw as a secondary retention measure.

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