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When misalignment between a motor shaft and a driven component causes vibration, noise, or premature wear, engineers and DIY machinists need a coupling that absorbs shock without sacrificing torque transmission. These flexible jaw spider shaft couplers are designed for CNC routers, stepper motor assemblies, pump drives, and general-purpose power transmission where bore sizes and shaft diameters vary across a build.
Each coupler consists of two aluminum hubs and a polyurethane spider insert. The outer diameter (D) is available in 14 mm (~0.55 in) and 20 mm (~0.79 in), with lengths of 22 mm, 25 mm, and 30 mm depending on the variant. Bore combinations (φd1 × φd2) range from 3 mm up to 10 mm, covering the most common stepper and servo motor shaft sizes used in hobby and light-industrial CNC builds.
Typical use cases include stepper-motor-to-leadscrew connections on CNC routers and 3D printer Z-axes, pump-to-motor shaft coupling in fluid transfer systems, and encoder or feedback device mounting in servo drive applications — all scenarios where a rigid coupling would transmit shock loads directly to bearings.
Each hub is machined from aluminum alloy for a lightweight yet rigid grip on the shaft. Set-screw clamping locks the bore securely without marring the shaft surface.
The six-jaw spider element absorbs torsional shock and compensates for angular, parallel, and axial misalignment — protecting motor bearings and extending drivetrain life.
Available in dozens of φd1 × φd2 bore combinations from 3 mm × 3 mm up to 10 mm × 10 mm, making it straightforward to match mismatched shaft diameters on both sides of the coupling.
Order as a single piece for prototyping or in packs of 5 or 10 for production runs and spare-parts inventory — all variants ship as complete coupler assemblies (two hubs + spider).
The jaw-and-spider geometry maintains near-zero backlash under normal operating loads, making these couplers suitable for position-critical CNC and encoder applications.
The spider insert can be swapped without removing the hubs from the shafts, simplifying maintenance on assembled machines.
| Outer Diameter (D) | 14 mm (~0.55 in) or 20 mm (~0.79 in) — see variant |
|---|---|
| Length (L) | 22 mm, 25 mm, or 30 mm — see variant |
| Bore 1 (φd1) | See variant options (3–10 mm) |
| Bore 2 (φd2) | See variant options (3–10 mm) |
| Hub Material | Aluminum alloy |
| Spider Material | Polyurethane (PU) |
| Coupling Type | Flexible jaw / spider (plum-type) |
| Shaft Fixation | Set screw clamping |
| Misalignment Tolerance | Angular: typically ±1°; Parallel: typically 0.2–0.5 mm |
| Quantity per Order | 1 Pcs / 5 Pcs / 10 Pcs — see variant |
| Package Contents | 2 × aluminum hubs + 1 × spider insert per coupler |
First measure the outer diameter of both shafts you need to connect (φd1 and φd2). Then select the overall coupler body size (D14 mm × L22 mm or D20 mm × L25/30 mm) that fits within your available space. The D14 mm body suits smaller NEMA 17 builds; the D20 mm body is better for NEMA 23 or larger pump shafts. If both shafts are the same diameter, choose a symmetric bore option (e.g., 5 mm × 5 mm).
Yes. The polyurethane spider insert accommodates a combination of angular misalignment (typically up to ±1°) and parallel offset (typically 0.2–0.5 mm). For best results, align shafts as closely as possible during installation — the spider is designed to compensate for residual misalignment, not to substitute for proper alignment.
Under normal operating loads the jaw-and-spider engagement produces near-zero backlash, making these couplers suitable for CNC router leadscrews and encoder shafts. Very high reversing torque loads can cause slight spider deflection; if sub-0.01 mm repeatability is critical, consider a rigid or bellows coupling instead.
Aluminum alloy has natural oxide-layer corrosion resistance suitable for most indoor and lightly humid environments. For prolonged outdoor or wet exposure, apply a light coat of anti-corrosion spray to the hub surfaces. The polyurethane spider is inherently resistant to moisture and mild oils.
These couplers are widely used with NEMA 17 and NEMA 23 stepper motors (common shaft diameters: 5 mm and 6.35 mm), servo motors, small DC gear motors, centrifugal pumps, and encoder mounting applications. Confirm your shaft diameters match the φd1 × φd2 bore option before ordering.
Installation requires only a hex key (Allen wrench) to tighten the set screws on each hub. The spider insert slides between the jaws of the two hubs and can be replaced without removing the hubs from the shafts — simply loosen the set screws slightly, slide one hub back, swap the spider, and re-tighten.
The 1 Pcs option is ideal for single-machine builds or testing a bore combination before committing to a larger order. The 5 Pcs pack suits small production runs or builds with multiple axes. The 10 Pcs pack offers the best per-unit value for batch production, repair stock, or workshop inventory.
