3 Mod #45 Steel Spur Gears Flat Gears 10T 11T 12T 13T~ 56T Blank Hole Gears

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3 Mod #45 Steel Spur Gears Flat Gears 10T 11T 12T 13T~ 56T Blank Hole Gears

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By HomeDIYer®

Mod/ Teeth: 3M 10T

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$17.94 USD

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In stock (500 units), ready to be shipped

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3 Mod #45 Steel Spur Gears — Precision Blank Bore Flat Gears for DIY Automation

When your motion-control build demands a gear that fits exactly the shaft you have — not the shaft someone else designed for — a blank bore spur gear is the answer. Makers, robotics builders, and CNC hobbyists who need a reliable 3 Mod steel spur gear without a pre-cut keyway or fixed bore will find this series covers tooth counts from 10T all the way to 56T, giving you the flexibility to machine the bore to your exact specification.

Each gear is machined from #45 carbon steel, a medium-carbon alloy known for its balance of strength and machinability. The flat (disc) profile keeps axial footprint minimal. Outer diameters scale with tooth count: the 10T gear measures approximately 36 mm (1.42 in) tip-to-tip, while the 56T reaches approximately 174 mm (6.85 in); hub thickness is typically 20–30 mm depending on the variant. Module 3 pitch means a 3 mm pitch diameter per tooth, fully compatible with any standard Mod 3 rack, pinion, or mating gear.

Typical use cases include DIY CNC router axis drives, open-frame robotic arm joints, conveyor indexing mechanisms, and educational automation rigs where a custom-bored gear is required. Long-tail search terms that describe this product well: module 3 steel spur gear blank bore, 45 steel flat gear 3M DIY, mod 3 gear 10T to 56T custom bore.

⚙️ Compatibility: Mates with any standard Module 3 (Mod 3) rack, pinion, or spur gear. Bore is blank — machine to your required shaft diameter and keyway.

✅ Key Features of These 3 Mod #45 Steel Spur Gears

🔩#45 Carbon Steel Construction — Medium-carbon steel delivers solid load-bearing capacity and resistance to wear under continuous rotational loads, suitable for moderate-duty automation applications.
🎯Blank Bore Design — No pre-drilled or pre-keyed bore means you machine the hole to your exact shaft size, eliminating the need to compromise on fit or use adapters.
📐Module 3 Standard Pitch — 3 mm pitch per tooth ensures full interchangeability with any Mod 3 rack, pinion, or mating gear in your drivetrain.
📏Wide Tooth-Count Range (10T – 56T) — 47 variants in a single product listing let you dial in the exact gear ratio your project requires without sourcing from multiple suppliers.
⚡Flat Disc Profile — The low-profile flat gear body minimises axial space consumption, making these gears well-suited for compact gearboxes and tight chassis layouts.
🔧Machinable & Weldable Material — #45 steel responds well to turning, milling, and drilling, so finishing the bore, adding a keyway, or welding a hub is straightforward on standard workshop equipment.

📐 Technical Specifications — Module 3 Steel Spur Gears

Module (Mod)	3
Tooth Count Range	10T – 56T (select variant)
Material	#45 Carbon Steel
Bore Type	Blank (unfinished) — machine to size
Gear Profile	Flat disc (no hub flange)
Pressure Angle	20°
Pitch Diameter	Module × Teeth (e.g., 3 × 20T = 60 mm)
Outer Diameter (tip)	See variant options
Hub / Face Width	See variant options
Surface Finish	Natural steel (uncoated)
Quantity per Order	1 piece

❓ Frequently Asked Questions

How do I choose the right tooth count for my project?

Gear ratio is determined by dividing the driven gear tooth count by the driving gear tooth count. For example, pairing a 10T pinion with a 30T gear gives a 3:1 reduction. Decide your required speed reduction or multiplication first, then select the tooth counts that achieve that ratio. The 10T–56T range here covers ratios from roughly 1:1 up to about 5.6:1 in a single stage when paired with a 10T driver.

What bore size should I machine into the blank?

The blank bore can be machined to any diameter that fits within the hub stock of the gear. As a conservative guide, leave at least 3–5 mm of wall thickness between the bore edge and the root circle of the teeth. For smaller gears (10T–15T), bore diameters up to approximately 10–15 mm are typical; larger gears (30T+) can accommodate 20 mm or more. Confirm the hub outer diameter for your specific variant before machining.

Are these gears compatible with Module 3 racks and pinions from other brands?

Yes. Module 3 is an internationally standardised pitch. Any Mod 3 gear, rack, or pinion with a matching 20° pressure angle will mesh correctly with these gears regardless of brand, provided the face widths are compatible.

How strong are #45 steel spur gears compared to aluminium or plastic alternatives?

#45 carbon steel has a tensile strength typically in the range of 600–800 MPa, significantly higher than 6061 aluminium (~310 MPa) and far above engineering plastics like POM or nylon. For moderate-duty automation, robotics, and CNC applications these gears offer a good balance of strength and machinability. For very high-speed or high-torque industrial applications, consider hardened or alloy steel gears.

Do these gears come with any corrosion protection?

The gears are supplied with a natural (uncoated) steel finish. For environments with moisture exposure, we recommend applying a light machine oil, grease, or a spray rust inhibitor after machining. If long-term corrosion resistance is critical, consider having the finished gear zinc-plated or black-oxide coated by a local finishing shop.

Can I use these gears in a vertical load-bearing orientation?

Yes, spur gears can transmit torque in any orientation. However, spur gears generate axial thrust only from shaft misalignment, not from the tooth geometry itself, so they are well-suited to vertical shaft arrangements. Ensure your shaft bearings are rated for the radial loads generated by the gear mesh force at your operating torque.

Is one piece included per order, or is it a set?

Each order includes 1 piece of the selected tooth-count variant. If you need multiple gears or a matched pair, simply increase the quantity or add multiple variants to your cart.

🛒 Select your Mod / Teeth count above, then add to cart.