0.5 Mod 55 Teeth Spur Gear With Step Bore 6/8/10/12mm Motor Transmission Gears

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0.5 Mod 55 Teeth Spur Gear With Step Bore 6/8/10/12mm Motor Transmission Gears

HomeDIYer

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By HomeDIYer®

Size: 0.5M 55T, Bore 6mm

Packing Quantity: 1 pcs

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$14.52 USD

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In stock (500 units), ready to be shipped

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0.5 Mod 55-Tooth Spur Gear — Smooth Motor Transmission for DIY Automation Builds

Finding a 0.5 module 55-tooth spur gear that fits your motor shaft without custom machining is a recurring frustration for robotics builders, CNC hobbyists, and small-workshop engineers. Whether you are designing a gear reduction stage for a stepper motor, a DC motor drive, or a compact servo transmission, you need a 55T spur gear that drops straight onto a standard shaft bore and meshes cleanly with your existing 0.5 Mod gear train.

These 0.5 Mod 55-tooth spur gears are machined from 45# medium-carbon steel, offering a reliable balance of surface hardness and structural toughness for sustained meshing loads. The module is 0.5 mm, the tooth count is 55T, and the pitch diameter is 27.5 mm (1.08 in). The outer (tip) diameter is 28.5 mm (1.12 in), calculated from the standard involute formula (Teeth + 2) × Module. Bore options are 6 mm, 8 mm, 10 mm, and 12 mm — all round bores suited to smooth motor shafts. Face width is typically 5–8 mm (0.20–0.31 in).

Typical use cases include 0.5 mod reduction stages on NEMA 17 and NEMA 23 stepper motor output shafts for 3D printer and CNC axis drives, compact DC motor transmission assemblies in robotic arm joints where a 55-tooth spur gear provides a useful ratio step, and small automation conveyor or indexing mechanisms requiring a module 0.5 steel gear with a larger tooth count for lower output speed.

⚙️ Compatible with all standard 0.5 module involute spur gear systems. Meshes with any 0.5 Mod mating gear regardless of tooth count. Round bore sizes (6 / 8 / 10 / 12 mm) suit common stepper motor, DC motor, and servo output shafts.

✅ Key Features of These 0.5 Mod 55-Tooth Spur Gears

🔩 45# Medium-Carbon Steel Construction — Machined from 45# steel (AISI 1045 equivalent) for a dependable combination of surface hardness and core toughness, resisting tooth wear under continuous meshing loads in automation and robotics drives.
📐 Precision 0.5 Module, 55-Tooth Involute Profile — Standard 20° pressure-angle 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 motor drives.
🎯 Four Round Bore Options for Direct Shaft Fit — Available in 6 mm, 8 mm, 10 mm, and 12 mm round bores to match your motor shaft without custom machining. Each bore is finished to close tolerance for a secure, concentric fit.
📦 Flexible Pack Quantities — 1 to 10 Pieces — Order in packs of 1, 2, 3, 4, 5, 8, or 10 pieces to match your project scale, with per-unit cost savings at higher quantities for workshop stocking or multi-axis builds.
🔄 Larger 55T Count for Useful Gear Ratio Stages — The 55-tooth count pairs with smaller pinion gears (e.g., 11T, 15T, 20T) to deliver practical reduction ratios in a compact 28.5 mm OD package, ideal for torque multiplication in robotic joints and indexing drives.
🛠️ 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 shafts within the listed bore range.

📐 Technical Specifications — 0.5 Mod Spur Gear

Module (Pitch)	0.5 mm
Number of Teeth	55T
Pitch Diameter	27.5 mm (1.08 in)
Outer Diameter (OD)	28.5 mm (1.12 in)
Face Width	Typically 5–8 mm (0.20–0.31 in)
Bore Options	6 mm / 8 mm / 10 mm / 12 mm (round)
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 motor shaft?

Select the bore that matches your motor's output shaft diameter. Common stepper motor shafts are 5 mm (NEMA 17) or 6.35 mm (NEMA 23 — use the 8 mm bore with a locking collar or sleeve adapter in this case). DC gear motors often use 6 mm, 8 mm, or 10 mm shafts. Choose the bore that is equal to or closest to your shaft diameter, then secure with a set screw or shaft collar. All bores in this listing are round (no keyway); if you need a keyed bore, see our keyway bore variants.

What are the pitch diameter and outer diameter of this 0.5 Mod 55T gear?

Using standard involute gear formulas: Pitch Diameter = Module × Teeth = 0.5 × 55 = 27.5 mm. Outer (Tip) Diameter = (Teeth + 2) × Module = 57 × 0.5 = 28.5 mm. These values apply to all bore variants in this listing and are consistent with any standard 0.5 Mod mating gear calculation.

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

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

Will this 55T gear mesh correctly with my existing 0.5 module gears?

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 55T gear will mesh correctly with any 0.5 Mod pinion or gear — whether it has 10, 20, 30, 45, or more teeth — provided the center distance is set to the sum of the two pitch radii: (PD₁ + PD₂) / 2.

Does 45# carbon steel resist corrosion in humid workshop environments?

45# carbon steel has limited inherent corrosion resistance compared to stainless steel. For humid or occasionally wet environments, apply a light machine oil or grease to the gear teeth and bore after installation and re-apply periodically. For enclosed gearboxes or indoor workshop use with standard lubrication maintenance, surface rust is not typically a concern. If long-term corrosion resistance is critical, consider a stainless-steel or zinc-plated alternative.

What gear ratio can I achieve by pairing this 55T gear with a smaller pinion?

Gear ratio = Driven Teeth ÷ Driver Teeth. Pairing this 55T gear with common pinion sizes gives: 55÷11T = 5:1 reduction, 55÷15T ≈ 3.67:1, 55÷20T = 2.75:1, 55÷25T = 2.2:1, 55÷30T ≈ 1.83:1. These ratios are useful for torque multiplication in robotic joints, indexing tables, and low-speed conveyor drives. All mating pinions must be 0.5 module with a 20° pressure angle.

What pack size should I order for a multi-axis or multi-stage build?

For a single gear pair, order at least 2 pcs. For a two-stage compound gear train with one 55T gear per stage, 4 pcs covers two complete stages. The 5-pack and 10-pack options provide better per-unit value and include spares for prototyping or future repairs. If you are building multiple identical assemblies or stocking a workshop, the 8-pack or 10-pack minimizes reorder frequency.

🛒 Select your Size and Packing Quantity above, then add to cart.