H-Type Synchronous Timing Pulley 12T-20T for 25mm Width Belt Bore 10-30mm CNC 3D

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H-Type Synchronous Timing Pulley 12T-20T for 25mm Width Belt Bore 10-30mm CNC 3D

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By HomeDIYer®

Tooth: 12T

Tooth Width: 27mm

Bore Dia: 10mm

Price:

$27.16 USD

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In stock (500 units), ready to be shipped

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H-Type Synchronous Timing Pulleys — Precise Power Transmission for CNC & DIY Automation

When your CNC router skips steps or your 3D printer loses position mid-print, the culprit is often a mismatched or worn timing pulley. These H-Type synchronous timing pulleys are engineered for makers, small-workshop builders, and automation hobbyists who need repeatable, slip-free motion transfer without the guesswork of sourcing compatible hardware.

Each pulley is machined from aluminum alloy with a natural or anodized finish and features a flanged bearing seat to keep the belt tracking true. The tooth profile follows the H-type (HTD-style trapezoidal) standard with a 25 mm (0.984 in) belt width. Tooth counts range from 12T to 20T, and bore diameters span 10 mm to 30 mm (0.39 in – 1.18 in) to suit a wide range of shaft sizes. A set-screw hub locks the pulley securely onto the shaft.

Typical use cases include CNC router X/Y axis drives, desktop 3D printer extruder and motion systems, DIY pick-and-place machines, and light-duty conveyor or indexing mechanisms where synchronous belt drive timing pulley accuracy is critical.

⚙️ Compatibility: Designed for H-type (HTD trapezoidal) synchronous belts with 25 mm width. Verify your belt pitch and width before ordering. Bore diameter must match your shaft — select from 10 / 12 / 15 / 17 / 20 / 25 / 30 mm options.

✅ Key Features of These H-Type Synchronous Timing Pulleys

🔩Flanged Bearing Design — Integrated flanges on both sides keep the belt centered and prevent lateral drift during high-speed operation.
⚙️Wide Tooth Range (12T–20T) — Six tooth-count options let you dial in the exact gear ratio needed for your drive system without custom machining.
📏Broad Bore Selection (10–30 mm) — Seven bore sizes accommodate common shaft diameters used in CNC spindles, stepper motors, and servo drives.
🏗️Aluminum Alloy Construction — Lightweight yet rigid material reduces rotational inertia while maintaining dimensional stability under continuous load.
🔐Set-Screw Hub Locking — Radial set-screw secures the pulley to the shaft without requiring keyways, simplifying installation and adjustment.
🖨️CNC & 3D Printer Ready — Tooth profile and belt-width spec match standard H-type drive systems used in desktop CNC routers and FDM 3D printers.

📐 Technical Specifications — H-Type Timing Pulley

Belt Type	H-Type Synchronous (HTD Trapezoidal)
Belt Width	25 mm (0.984 in)
Tooth Count	12T / 14T / 15T / 16T / 18T / 20T (see variant options)
Bore Diameter	10 / 12 / 15 / 17 / 20 / 25 / 30 mm (see variant options)
Material	Aluminum Alloy
Flange	Double-flanged bearing seat
Hub Locking	Set-screw
Finish	See variant options
Outer Diameter	See variant options
Hub Length	See variant options
Compatible Applications	CNC routers, 3D printers, DIY automation, conveyor drives

❓ Frequently Asked Questions

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

The tooth count determines your drive ratio. A smaller pulley (e.g., 12T) on the motor paired with a larger pulley on the driven shaft reduces speed and increases torque. For CNC and 3D printer motion systems, 16T–20T pulleys are common on the motor side for a balanced speed-to-torque ratio. Match your tooth count to your belt's pitch and the ratio your system requires.

Which bore diameter should I select for my stepper motor shaft?

Most NEMA 17 stepper motors use a 5 mm shaft, while NEMA 23 motors typically use an 8 mm or 1/4 in shaft. These pulleys start at 10 mm bore — if your shaft is smaller, you will need a reducing bushing or a different pulley series. For servo motors and spindle shafts, bore sizes of 12–30 mm are commonly used. Always measure your shaft diameter before selecting.

Are these pulleys compatible with standard HTD belts?

These pulleys use an H-type trapezoidal tooth profile designed for H-type synchronous belts with 25 mm width. They are not interchangeable with GT2 or MXL profile belts. Confirm your belt's tooth profile and width match before ordering to ensure proper meshing and load transfer.

How strong is the set-screw connection — will it slip under load?

The set-screw hub provides adequate holding force for typical CNC and 3D printer loads. For higher-torque applications, ensure the screw is tightened against a flat on the shaft (D-shaft) rather than a round shaft to maximize grip. If your application involves shock loads or very high torque, consider adding a shaft key or using a clamping-style hub pulley instead.

Will the aluminum construction corrode in humid or outdoor environments?

Aluminum alloy has natural oxidation resistance that forms a protective layer in most indoor environments. For humid workshops or light outdoor enclosures, the material performs reliably without additional treatment. For prolonged exposure to moisture, salt, or chemicals, applying a light coat of machine oil or using an anodized variant will extend service life.

Can I use these pulleys on both the drive and driven side of a belt system?

Yes. These pulleys can be used on either the motor (drive) side or the load (driven) side. Simply select the appropriate tooth count for each position to achieve your desired drive ratio. Using the same tooth count on both sides gives a 1:1 ratio, while mixing counts (e.g., 12T drive / 20T driven) reduces output speed and increases torque.

What is the difference between tooth width and bore diameter in the variant options?

Tooth Width (27 mm listed in variants) refers to the face width of the pulley teeth — the dimension that contacts the belt. All variants in this listing use a 27 mm tooth face width to accommodate a 25 mm wide belt with side clearance. Bore Diameter is the hole through the center of the pulley that fits onto your shaft. Select the bore that matches your shaft size.

🛒 Select your Tooth count and Bore Dia above, then add to cart.