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When your CNC router, 3D printer, or robotic arm loses belt tension mid-run, the result is skipped steps, misaligned cuts, and wasted material. Engineers and makers who demand repeatable accuracy need an idler pulley that holds its position under load without adding friction or play. These HTD3M 15mm idler timing drive pulleys are designed for exactly that role — keeping your belt path taut and aligned across the full duty cycle.
Each pulley is machined from aluminum alloy with a natural anodized finish, featuring an HTD 3M tooth profile (3mm pitch) and a 15mm (0.59 in) tooth width. Bore options range from 4mm to 25mm (0.16–0.98 in), and tooth counts span 15 to 50 teeth, giving you precise pitch diameter control from approximately 14.3mm to 47.7mm (0.56–1.88 in). The flanged design keeps the belt tracking centrally without lateral drift.
Typical use cases include idler tensioner assemblies on belt-driven CNC gantries, timing belt routing on delta-style 3D printers, and auxiliary drive paths in conveyor and pick-and-place automation. The HTD3M profile is also widely used in laser cutter X/Y stages and lightweight robotic joint drives where low backlash and consistent pitch engagement are critical.
| Belt Profile | HTD 3M (3mm pitch) |
|---|---|
| Tooth Width | 16mm (0.63 in) |
| Tooth Count Options | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50 |
| Bore Options | 4, 5, 6, 6.35, 7, 8, 10, 12, 12.7, 14, 15, 16, 17, 18, 19, 20, 25mm |
| Pitch Diameter Range | Approx. 14.3mm (15T) to 47.7mm (50T) |
| Material | Aluminum alloy |
| Finish | Natural anodized |
| Flange | Yes (both sides) |
| Quantity per Order | 1 piece |
| Weight | See variant options |
Tooth count determines the pitch diameter of the pulley. Use the formula: Pitch Diameter = (Tooth Count × Pitch) ÷ π. For HTD 3M, pitch = 3mm. A 20-tooth pulley has a pitch diameter of approximately 19.1mm. Choose a tooth count that gives you the center distance and belt length your design requires. For idler use, the tooth count mainly affects the wrap angle and the minimum bend radius the belt experiences.
For bearing-mounted idlers, select a bore that matches the outer diameter of your chosen bearing. Common pairings: 4mm bore → 625ZZ bearing (5mm OD), 5mm bore → 625ZZ or 626ZZ, 8mm bore → 688ZZ (16mm OD). Always verify the bearing OD against the bore before ordering. A light press fit or retaining compound is typically used to secure the bearing in the bore.
These aluminum HTD3M pulleys are well-suited for light-to-medium duty motion control — CNC routers, 3D printers, laser cutters, and small conveyor systems. The HTD tooth profile handles higher torque than trapezoidal MXL/T profiles of the same pitch. For very high torque or industrial continuous-duty applications, consult the belt manufacturer's load ratings and verify the pulley bore wall thickness is adequate for your shaft clamping method.
The aluminum alloy body with anodized finish provides good resistance to oxidation and light moisture exposure. For prolonged outdoor or high-humidity environments, periodic inspection is recommended. These pulleys are not rated for immersion or highly corrosive chemical environments. For such conditions, consider stainless steel alternatives.
Yes. The HTD 3M tooth profile is an industry-standard geometry. These pulleys are compatible with any HTD 3M timing belt with a 15mm or 16mm width from any manufacturer, including Gates, Bando, and generic suppliers. Always match the belt width to the pulley tooth width (16mm) for proper flange clearance.
Yes. While listed as idler pulleys, these can be used as drive pulleys when secured to a motor shaft using a set screw, keyway, or shaft collar. Ensure the bore matches your shaft diameter. Note that these pulleys do not include a set screw or keyway as standard — you will need to add your own clamping method if used as a drive pulley.
The variant option label shows "16mm" as the tooth width (the actual machined pulley groove width), while the product title references "15mm" as the nominal belt width these pulleys are designed to work with. A 16mm groove width accommodates a 15mm-wide belt with appropriate clearance. This is standard practice — pulley groove width is typically 1mm wider than the nominal belt width.
