Spur Gear 1.0 Mod w Steps 21T~35T Metal Spur Gear #45 Steel Blacked Spur Gear

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Spur Gear 1.0 Mod w Steps 21T~35T Metal Spur Gear #45 Steel Blacked Spur Gear

Name: Spur Gear 1.0 Mod w Steps 21T~35T Metal Spur Gear #45 Steel Blacked Spur Gear
Brand: HomeDIYer
Price: 10.66 USD
Availability: InStock

HomeDIYer

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By HomeDIYer®

Module/Teeth: 1M 21T

Bore Diameter: 6mm

Price:

$10.66 USD

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In stock (500 units), ready to be shipped

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1.0 Mod Blacked Spur Gears — Precision #45 Steel for Reliable Power Transmission

When a loose or mismatched gear causes a robot arm to stutter, a CNC axis to skip, or a DIY drive train to strip under load, the fix starts with choosing the right module and tooth count from the start. These 1.0 mod blacked spur gears are engineered for makers, robotics builders, and mechanical engineers who need repeatable, tight-tolerance power transmission without sourcing custom parts.

Each gear is machined from #45 medium-carbon steel and finished with a black oxide coating that reduces surface friction and provides a base layer of corrosion resistance. The range covers 21T through 35T tooth counts, with bore diameters spanning 5 mm to 17 mm (approximately 0.20" to 0.67"). Bore styles include standard round bores, stepped bores (Step 17 mm and Step 20 mm hub lengths), D-bore configurations, and keyed bores with keyway dimensions of 3×1.4 mm, 4×1.8 mm, or 5×2.3 mm — giving you the exact shaft interface your application demands.

These 1.0 mod spur gears suit a wide range of use cases: compact gear reduction stages in desktop CNC routers, servo-driven pan-tilt mechanisms in camera rigs, and multi-stage gearboxes in educational robotics platforms. Builders replacing worn gears in 3D printer extruder drives or small conveyor systems will find the stepped and keyed bore options especially useful for locking onto motor shafts without additional set screws.

⚙️ Compatibility Note: These gears are Module 1.0 (1.0 Mod / 1M). They mesh correctly only with other 1.0 Mod gears. Verify your mating gear's module before ordering. Bore diameter and bore style must match your shaft diameter and interface type — see variant options for the full selection.

✅ Key Features of These 1.0 Mod Blacked Spur Gears

🔩 #45 Steel Construction

Machined from #45 medium-carbon steel for a balance of machinability, tensile strength, and wear resistance suited to moderate-load gear drives.

🖤 Black Oxide Finish

The blacked surface treatment reduces adhesive wear between meshing teeth and provides a base level of corrosion resistance in low-humidity environments.

📐 Wide Tooth Count Range: 21T – 35T

Fifteen tooth count options from 21T to 35T let you dial in your gear ratio precisely without resorting to custom machining or non-standard modules.

🔧 Multiple Bore Styles

Choose from standard round bores (5–17 mm), stepped bores (Step 17 mm / Step 20 mm hub), D-bore configurations, or keyed bores (3×1.4 mm, 4×1.8 mm, 5×2.3 mm keyways) to match your shaft interface exactly.

🎯 1.0 Module Precision Profile

Ground to 1.0 Mod tooth profile standards, ensuring smooth mesh engagement and consistent pitch circle diameter across the full 21T–35T range.

🏗️ Broad Application Fit

Suitable for desktop CNC machines, robotics gear stages, servo-driven mechanisms, extruder drives, and small conveyor systems where compact, reliable spur gear sets are required.

📐 Technical Specifications — 1.0 Mod Spur Gears

Module	1.0 (1M)
Tooth Count Range	21T – 35T (see variant options)
Material	#45 Medium-Carbon Steel
Surface Finish	Black Oxide (Blacked)
Bore Diameter Range	5 mm – 17 mm (approx. 0.20" – 0.67")
Bore Styles Available	Standard Round, Stepped (17 mm / 20 mm hub), D-Bore, Keyed (3×1.4 mm / 4×1.8 mm / 5×2.3 mm)
Pressure Angle	See variant options
Face Width	See variant options
Pitch Circle Diameter	Tooth Count × 1.0 mm (e.g., 25T = 25 mm PCD)
Gear Type	Spur Gear (parallel axis)
Compatible Module	1.0 Mod mating gears only
Quantity per Order	1 piece

❓ Frequently Asked Questions

What does "1.0 Mod" mean and will it mesh with my existing gears?

"Module" (Mod) is the metric standard for gear tooth size. A 1.0 Mod gear has a tooth pitch of π × 1.0 mm. Two gears mesh correctly only when they share the same module. If your existing gear is 1.0 Mod, these gears will mesh with it. If your gear is a different module (e.g., 0.8 Mod or 1.5 Mod), they will not mesh correctly. Check your existing gear's documentation or measure the pitch circle diameter divided by tooth count to confirm the module.

How do I choose the right bore diameter and bore style?

Measure your motor or shaft diameter precisely with calipers. Select the bore diameter that matches your shaft. For a plain shaft, choose a standard round bore. If your shaft has a flat (D-cut), select the D-bore option with matching dimensions. For a shaft with a keyway, choose the keyed bore option whose keyway dimensions (e.g., 3×1.4 mm) match your shaft's key. Stepped bores (Step 17 mm or Step 20 mm) provide an extended hub that can be useful when you need more axial engagement or want to position the gear further from a mounting face.

How strong are these gears under load?

#45 steel has a typical tensile strength in the range of 600–800 MPa depending on heat treatment. These gears are suited to moderate-load applications such as robotics joints, CNC axis drives, and small conveyor stages. For very high-torque or shock-load applications, consider whether a hardened or alloy steel gear would be more appropriate for your specific torque and speed requirements.

Does the black oxide finish protect against rust?

Black oxide provides a thin conversion coating that offers a base level of corrosion resistance and reduces surface friction between meshing teeth. It is not a heavy-duty rust barrier like zinc plating or powder coating. For use in humid or outdoor environments, apply a light machine oil or grease to the gear teeth and bore after installation to extend service life.

Which tooth count should I choose for my gear ratio?

Your gear ratio is determined by dividing the driven gear's tooth count by the driving gear's tooth count. For example, pairing a 21T driving gear with a 35T driven gear gives a reduction ratio of approximately 1.67:1. Map out your required input and output speeds, then select tooth counts from the 21T–35T range that achieve your target ratio. If you need ratios outside this range, consider a multi-stage gear train.

Can I use these gears in a 3D printer extruder or CNC router?

Yes. 1.0 Mod steel spur gears are commonly used in desktop CNC router axis drives and in some extruder gear sets where a metal-to-metal mesh is preferred over plastic gears. Verify that the bore diameter matches your motor shaft, that the tooth count gives you the correct drive ratio, and that the face width is compatible with your existing gear stack. The keyed and D-bore variants are particularly useful for securing the gear to a motor shaft without slippage.

What is the pitch circle diameter for each tooth count?

For a 1.0 Mod gear, the pitch circle diameter (PCD) equals the tooth count in millimeters. For example: 21T = 21 mm PCD, 25T = 25 mm PCD, 30T = 30 mm PCD, 35T = 35 mm PCD. The outside diameter (OD) is approximately PCD + 2 mm (i.e., tooth count + 2 mm). Use these values to calculate center distances when designing your gear layout.

🛒 Select your Module/Teeth count and Bore Diameter above, then add to cart.