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When misalignment, vibration, or torque shock threatens your drive system, a rigid coupling is the last thing you want. Engineers, machinists, and DIY builders working on CNC routers, stepper motor assemblies, pump drives, and servo systems need a coupling that absorbs shock, compensates for minor shaft misalignment, and transmits torque reliably — without backlash buildup over time.
This spider jaw plum coupler is machined from aluminum alloy and consists of two jaw hubs paired with a polyurethane spider insert. The outer diameter is 35mm (≈1.38 in) with a body length of 50mm (≈1.97 in). Bore sizes range from 8mm to 19mm (≈0.31–0.75 in) for both φd1 and φd2, covering equal and stepped bore combinations to suit a wide range of shaft pairings.
Typical applications include CNC axis drives requiring low-backlash shaft connection, pump-to-motor couplings in fluid handling systems, and stepper or servo motor shaft connections in automation and robotics builds. The jaw design accommodates angular, parallel, and axial misalignment while the spider element dampens vibration and protects connected components.
Both coupling halves are machined from aluminum alloy for a balance of strength and reduced rotational inertia, keeping your drive system responsive.
The jaw spider element absorbs shock loads and dampens vibration between connected shafts, protecting motors, encoders, and driven equipment from impact damage.
Available in equal-bore (e.g., 10mm × 10mm) and stepped-bore (e.g., 8mm × 12mm) combinations, covering a broad range of motor and driven shaft diameters in a single product family.
The jaw-and-spider design accommodates angular misalignment (typically up to 1°), parallel offset, and axial displacement, reducing bearing load on connected shafts.
The interference fit between jaw teeth and spider lobes minimizes backlash, making this coupling suitable for positioning applications such as CNC axis drives and servo systems.
Order a single coupling for a repair or replacement, or stock up with 3- or 5-piece packs for multi-axis builds and workshop inventory.
| Coupling Type | Spider Jaw / Plum Coupler |
|---|---|
| Hub Material | Aluminum Alloy |
| Spider Insert Material | Polyurethane (PU) |
| Outer Diameter (D) | 35mm (≈1.38 in) |
| Body Length (L) | 50mm (≈1.97 in) |
| Bore Diameter φd1 | 8mm – 19mm (see variant options) |
| Bore Diameter φd2 | 8mm – 19mm (see variant options) |
| Bore Combination | Equal bore and stepped bore available |
| Quantity per Order | 1 Pcs / 3 Pcs / 5 Pcs (see variant options) |
| Finish | See variant options |
| Applicable Shaft Types | Round shafts with keyway or set screw |
| Fastening Method | Set screw (grub screw) |
Measure the outer diameter of each shaft you need to connect. Select φd1 to match your driving shaft (e.g., motor shaft) and φd2 to match your driven shaft (e.g., lead screw or pump shaft). If both shafts are the same diameter, choose an equal-bore variant such as 10mm × 10mm. If they differ, select the appropriate stepped-bore combination from the variant options.
Torque capacity depends on bore size, set screw engagement, and the spider insert durometer. For light-duty CNC and stepper motor applications with shaft diameters in the 8–12mm range, these couplings are typically rated for torque loads in the range of 3–10 Nm. For higher-torque servo or pump applications, confirm your torque requirements against the bore size selected. Contact us to confirm suitability for demanding applications.
Yes. The jaw-and-spider design provides low backlash transmission, which is important for accurate positioning on CNC X, Y, and Z axes. The coupling compensates for minor shaft misalignment between the stepper motor and lead screw, reducing binding and bearing wear. It is widely used in DIY CNC builds and light industrial CNC machines.
The aluminum alloy hubs offer good resistance to oxidation and light moisture exposure typical of workshop and indoor industrial environments. For applications involving water, coolant splash, or outdoor exposure, consider applying a light protective coating or selecting a stainless steel coupling for more demanding corrosion resistance requirements.
Yes, spider jaw couplings are compatible with servo motors. The polyurethane spider element dampens torque spikes during rapid acceleration and deceleration cycles, protecting the servo encoder and gearbox. Ensure the bore size matches your servo shaft diameter and that the coupling's torque rating is appropriate for your servo's peak torque output.
Equal-bore variants (e.g., 10mm × 10mm) connect two shafts of the same diameter. Stepped-bore variants (e.g., 8mm × 12mm) connect shafts of different diameters, which is common when coupling a smaller motor shaft to a larger lead screw or pump shaft. Both variants share the same D35mm × L50mm outer dimensions.
Each hub is secured to its shaft using set screws (grub screws) that clamp against the shaft surface. For improved torque transmission and to prevent slipping, a flat (keyway) ground on the shaft is recommended for higher-load applications. Ensure set screws are tightened to the appropriate torque using the correct hex key size.
