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When misalignment, vibration, or shaft runout disrupts your CNC router, 3D printer, or lead-screw drive, a rigid coupling becomes the weakest link. These flexible plum spider jaw couplings are engineered for builders, machinists, and automation engineers who need reliable torque transmission with built-in compensation for angular and parallel shaft misalignment — without sacrificing positional accuracy.
Each coupling consists of two precision-machined aluminum hubs and a polyurethane spider insert (plum-shaped elastomer). Available in Set Screw Type and Clamping Type configurations, with 2-jaw and 3-jaw hub options. Outer diameters range from 14 mm (0.55 in) to 35 mm (1.38 in); lengths from 22 mm (0.87 in) to 42 mm (1.65 in). Bore sizes span 3 mm to 19 mm to suit a wide range of motor and lead-screw shaft diameters.
Typical applications include CNC stepper motor shaft connections on routers and mills, lead-screw couplings on linear actuators and 3D printer Z-axes, servo motor drives in pick-and-place machines, and encoder shaft connections requiring low backlash flexible coupling for precision positioning.
| Coupling Type | Set Screw Type / Clamping (Split-Clamp) Type |
|---|---|
| Hub Configuration | 2-Jaw / 3-Jaw |
| Hub Material | Aluminum alloy |
| Spider Insert Material | Polyurethane elastomer |
| Outer Diameter (OD) | 14 mm – 35 mm (0.55 in – 1.38 in) — See variant options |
| Coupling Length (L) | 22 mm – 42 mm (0.87 in – 1.65 in) — See variant options |
| Bore Diameter (d1 x d2) | 3 mm – 19 mm — See variant options |
| Surface Finish | Anodized aluminum — See variant options |
| Quantity per Order | 1 Pcs or 5 Pcs — See variant options |
| Weight | See variant options |
Set Screw Type couplings use a grub screw that presses directly against the shaft. They are compact and easy to install but can leave a small mark on the shaft and may loosen under heavy vibration. Clamping (split-clamp) Type couplings grip the shaft circumferentially with a bolt-tightened clamp, providing a more secure, slip-free hold and allowing shaft removal without damage. For precision CNC and 3D printer applications where repeatability matters, the Clamping Type is generally preferred.
2-jaw hubs engage the spider insert at two contact points, offering higher torque capacity and straightforward spider replacement. 3-jaw hubs distribute load across three contact points, resulting in smoother torque transmission, lower vibration at higher RPM, and better torsional stiffness. For most stepper motor CNC applications, either works well; 3-jaw is preferred for servo drives or higher-speed applications.
Measure your motor shaft diameter and lead-screw diameter precisely with a caliper. Select d1 (motor-side bore) and d2 (load-side bore) to match. If both shafts are the same diameter, choose a matching d1×d2 option (e.g., 5mm×5mm). If the shafts differ in diameter, select the "d1≠d2, Leave a message" option and specify your two shaft diameters in the order notes.
The polyurethane spider insert typically accommodates angular misalignment up to approximately 1°, parallel (radial) offset up to 0.2–0.5 mm, and axial displacement up to 1–2 mm depending on the coupling size. For best results, align shafts as closely as possible and use the coupling's flexibility only to absorb residual misalignment.
The polyurethane spider insert is a wear component and will eventually degrade under continuous load, heat, or chemical exposure. In most light-duty CNC and 3D printer applications, the spider lasts for years of normal use. When it does wear, only the spider needs replacement — the aluminum hubs remain serviceable. Ensure you match the jaw count (2-jaw or 3-jaw) and OD of your existing hubs when ordering a replacement.
These flexible jaw couplings are well-suited for low-to-medium torque applications typical of NEMA 17 and NEMA 23 stepper motors and small servo drives. For specific torque and RPM ratings for each size, contact us to confirm. For very high-torque or high-speed industrial drives, a rigid or disc coupling may be more appropriate.
The anodized aluminum hubs offer good corrosion resistance for typical workshop environments with occasional moisture exposure. The polyurethane spider insert resists oils and mild chemicals but should not be submerged or exposed to strong solvents. For outdoor or wash-down environments, inspect the spider periodically for degradation.
