1.5 Module Spur Gear — Precision 45 Steel Flat Gears for Reliable Power Transmission
Stripped gears and mismatched modules are a constant headache for engineers and DIY builders who need dependable torque transfer. These 1.5 Mod flat spur gears are machined from 45 carbon steel, offering the strength and dimensional consistency that robotics builders, automation integrators, and small-batch manufacturers demand. Whether you're replacing a worn gear or designing a new drivetrain from scratch, this series gives you a verified starting point.
Each gear is cut to a 1.5 module (Mod 1.5) standard with a flat (no hub) profile. The tooth count runs from 12T to 85T, with outer diameters spanning 21mm to 130.5mm (approximately 0.83–5.14 in). Tooth pitch diameter follows the standard formula: PD = Module × Teeth. All gears in this series share the same pressure angle and module, making them fully intermeshable with any other Mod 1.5 gear.
Typical applications include open-frame robot joints, conveyor drive stages, 3D printer extruder gearboxes, CNC axis reduction stages, and custom gearhead assemblies where a flat gear profile is preferred over a hubbed design. The 45 steel construction handles moderate-to-high torque loads without the brittleness of cast iron alternatives.
⚙️ Compatibility: Mod 1.5 standard — meshes with any Mod 1.5 spur or helical gear. Pressure angle: 20°. Material: 45 carbon steel (uncoated). Profile: flat (no hub/boss).
✅ Key Features of These 1.5 Mod 45 Steel Spur Gears
🔩Wide Tooth Range
12T to 85T in a single series — OD 21mm to 130.5mm — covering most compact and mid-size drive applications.
🏗️45 Carbon Steel
Higher tensile strength than mild steel; suitable for moderate-to-high torque transmission without surface hardening.
📐Flat Gear Profile
No hub or boss — ideal for custom shaft mounting with set screws, keyways, or press-fit bushings machined to your spec.
🔄Mod 1.5 Standard
Fully interchangeable with any other Mod 1.5 gear in your system; 20° pressure angle for smooth, low-noise meshing.
📦Bulk Quantity Options
Available in 1, 2, 3, 4, 5, or 10-piece quantities — order exactly what your build or production run requires.
🛠️Broad Application Fit
Robotics joints, CNC reduction stages, conveyor drives, 3D printer gearboxes, and custom automation assemblies.
📐 Technical Specifications — 1.5 Mod Flat Spur Gear
| Module |
1.5 |
| Pressure Angle |
20° |
| Tooth Count Range |
12T – 85T |
| Outer Diameter Range |
21mm – 130.5mm (0.83–5.14 in) |
| Gear Profile |
Flat (no hub) |
| Material |
45 Carbon Steel |
| Surface Treatment |
Uncoated (natural finish) |
| Bore Diameter |
See variant options |
| Face Width (Thickness) |
See variant options |
| Pitch Diameter |
Module × Teeth (e.g. 1.5 × 20T = 30mm PD) |
| Compatible Module |
Mod 1.5 (meshes with any Mod 1.5 gear) |
| Available Quantities |
1 / 2 / 3 / 4 / 5 / 10 pcs |
❓ Frequently Asked Questions
How do I choose the right tooth count for my application?
Select based on your required gear ratio and available center distance. For a 2:1 reduction, pair a 20T driver with a 40T driven gear. Center distance = (Driver PD + Driven PD) / 2 = (Module × T1 + Module × T2) / 2. All gears in this listing share Mod 1.5, so any two teeth counts can be meshed together.
What is the outer diameter for a specific tooth count?
OD = Module × (Teeth + 2). For Mod 1.5: 12T → 21mm, 20T → 33mm, 30T → 48mm, 40T → 63mm, 50T → 78mm, 60T → 93mm, 70T → 108mm, 85T → 130.5mm. Select the exact variant in the dropdown to confirm the OD before ordering.
Can these gears mesh with my existing Mod 1.5 gears from another supplier?
Yes. Module and pressure angle are the two parameters that determine mesh compatibility. These gears are Mod 1.5 with a 20° pressure angle — the most common standard — so they will mesh correctly with any other Mod 1.5 / 20° gear regardless of brand or origin.
How strong are 45 steel gears compared to other materials?
45 carbon steel (equivalent to C45 / SAE 1045) has a tensile strength of approximately 600–800 MPa in the normalized condition. It is significantly stronger than aluminum or nylon gears and suitable for moderate-to-high torque applications. For very high-load or high-speed applications, consider surface hardening (induction or case hardening) after purchase.
The gear has no hub — how do I mount it on a shaft?
The flat profile means the bore must be machined or adapted to your shaft diameter. Common methods include: drilling and tapping for a set screw, broaching a keyway, pressing in a keyed bushing, or using a shaft collar. Specify your shaft diameter to a local machine shop for a precise bore-and-key operation.
Can I order a mix of different tooth counts in one order?
Each variant (Teeth-OD selection) is a separate SKU. To order multiple tooth counts, add each variant to your cart individually. The QTY(Pcs) option lets you select 1–10 pieces per variant, so you can build a complete gear set in a single checkout.
What is the lead time and are these in stock?
All listed variants are stocked and ready to ship. Select your tooth count and quantity above, then add to cart for the fastest dispatch. Contact us if you need quantities beyond 10 pieces per variant for bulk pricing.
🛒 Select your tooth count (Teeth-OD) and quantity above, then add to cart.
