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When shaft misalignment or vibration throws off your CNC router, 3D printer, or motor-driven machine, the coupling is often the first thing to fail. Engineers, makers, and machine builders who demand consistent torque transmission and long service life rely on aluminum plum flexible shaft couplings to bridge the gap between motor and lead screw without sacrificing accuracy.
Each coupling is machined from aluminum alloy with a polyurethane (PU) spider insert seated between the two hubs. Outer diameters range from 30 mm to 40 mm (~1.18"–1.57"), heights from 30 mm to 55 mm (~1.18"–2.17"), and inner bore sizes span 6 mm × 6 mm up to 19 mm × 19 mm (square bores) as well as mixed rectangular bores — covering the most common NEMA stepper motor shaft and lead-screw combinations. Set screws lock each hub securely onto the shaft.
Typical applications include CNC router Z-axis lead-screw coupling, NEMA 17/23 stepper motor to ball-screw connections, laser engraver axis drives, and light-duty servo motor linkages where angular and parallel misalignment compensation is needed.
Both hubs are machined from aluminum alloy for a lightweight yet rigid frame that resists deformation under continuous rotational load.
The PU plum-shaped spider absorbs angular, parallel, and axial misalignment while dampening vibration — protecting both motor bearings and lead-screw nuts.
OD 30 mm and 40 mm bodies with bore IDs from 6 × 6 mm to 19 × 19 mm cover the most common CNC and 3D-printer shaft pairings in a single product line.
Radial set screws on each hub clamp firmly onto flat-sided or round shafts, preventing slippage during direction reversals and rapid acceleration cycles.
The flexible spider decouples motor resonance from the driven axis, reducing audible noise and extending the service life of downstream mechanical components.
Split-hub design allows installation and removal without disassembling the full drive train — ideal for prototyping, maintenance, and iterative machine builds.
| Material — Hubs | Aluminum alloy |
|---|---|
| Material — Spider Insert | Polyurethane (PU) |
| Outer Diameter (OD) | 30 mm (~1.18") / 40 mm (~1.57") — see variant options |
| Height | 30–55 mm (~1.18"–2.17") — see variant options |
| Inner Bore (ID) | 6×6 mm to 19×19 mm (square & rectangular) — see variant options |
| Locking Method | Radial set screws |
| Finish | Natural anodized aluminum |
| Misalignment Tolerance | Angular: typically ±1°; Parallel: typically 0.2–0.5 mm |
| Compatible Motor Types | NEMA 17, NEMA 23 stepper motors; light-duty servo motors |
| Quantity per Order | See variant options |
Match the Inner Diameter (ID) of the coupling to your motor shaft size and lead-screw bore. For example, if your NEMA 17 motor has a 5 mm round shaft and your lead screw has an 8 mm diameter, select the variant whose ID pair covers those two dimensions. Check the "Choose Model" dropdown — each option lists OD, Height, and both bore IDs clearly.
Yes. The polyurethane spider insert is specifically designed to accommodate angular misalignment of typically ±1° and parallel (radial) misalignment of approximately 0.2–0.5 mm. For best results, minimize misalignment during installation to extend spider life and maintain positioning accuracy.
Aluminum alloy has natural oxidation resistance suitable for indoor workshop and enclosed machine environments. For high-humidity or outdoor applications, consider applying a light protective coating. The PU spider insert is also resistant to oils and mild solvents commonly found in machining environments.
Yes, the set screws can grip round shafts, though adding a small flat (D-cut) to the shaft with a file significantly improves torque retention and prevents rotational slippage under load. For CNC and 3D-printer applications with moderate torque, round shafts typically work without modification.
The OD 40 mm couplings are physically larger and generally accommodate larger bore IDs (up to 19 × 19 mm), making them suited for NEMA 23 motors and larger lead screws. The OD 30 mm versions are more compact and cover smaller bore combinations, ideal for NEMA 17 and space-constrained builds. Both share the same plum-spider design and locking mechanism.
The polyurethane spider is a separate component seated between the two hubs. In many cases it can be replaced independently without purchasing a new complete coupling — simply loosen the set screws, slide the hubs apart, swap the spider, and reassemble. Contact us to confirm spider availability for your specific model.
These couplings are designed for the moderate-speed, moderate-torque demands of CNC stepper motor and lead-screw drives. For high-speed spindle or high-torque servo applications, please contact us to confirm suitability, as maximum RPM and torque ratings vary by model size.
