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When a rigid connection between your motor and lead screw causes vibration, backlash, or premature wear, the right flexible coupling makes all the difference. These CNC shaft couplers are designed for makers, machinists, and automation engineers who need reliable torque transmission with built-in tolerance for shaft misalignment — without sacrificing positional accuracy.
Each coupler consists of two aluminum alloy hubs and a polyurethane spider insert (plum-type elastomer). Bore sizes range from 3 mm (0.12 in) up to 25 mm (0.98 in) on each side, with outer diameters spanning 14 mm (0.55 in) to 45 mm (1.77 in) and lengths from 22 mm (0.87 in) to 66 mm (2.60 in). Both metric and inch-fractional bore combinations (including 6.35 mm / 1/4 in) are available across the variant range.
Typical applications include NEMA 17 and NEMA 23 stepper motor to lead screw connections on 3D printers and CNC routers, servo motor shaft coupling on laser engravers, and flexible shaft coupling for ball screw assemblies in DIY milling machines and pick-and-place systems.
Covers d1 and d2 bore combinations from 3 mm up to 25 mm, including 6.35 mm (1/4 in) imperial sizes — one product line for metric and inch shafts.
Polyurethane spider absorbs angular, parallel, and axial misalignment while dampening vibration and shock loads between motor and driven shaft.
Lightweight yet rigid aluminum construction keeps rotational inertia low — critical for responsive acceleration and deceleration in CNC and 3D printing applications.
Seven outer diameter / length combinations (D14×L22 through D45×L66) let you match the coupler to your motor frame size and available shaft clearance.
Split-hub clamp design with set screws secures each bore independently — no keyway required, and re-centering is straightforward if shaft positions change.
The elastomer spider can be replaced independently of the aluminum hubs, extending service life and reducing maintenance cost on high-cycle machines.
| Coupler Type | Plum / Spider Jaw (Oldham-style elastomer) |
|---|---|
| Hub Material | Aluminum alloy |
| Spider Insert Material | Polyurethane (PU) elastomer |
| Bore d1 Range | 3 mm – 25 mm (metric & 6.35 mm / 1/4 in imperial) |
| Bore d2 Range | 3 mm – 25 mm (metric & 6.35 mm / 1/4 in imperial) |
| Outer Diameter (D) | 14 mm / 20 mm / 25 mm / 30 mm / 45 mm — see variant options |
| Overall Length (L) | 22 mm / 25 mm / 30 mm / 40 mm / 42 mm / 66 mm — see variant options |
| Finish | Natural anodized aluminum |
| Fastening Method | Clamp-style split hub with set screws |
| Misalignment Tolerance | See variant options |
| Max Torque | See variant options |
| Weight | See variant options |
Measure the outer diameter of each shaft you need to connect — your motor shaft is d1 and your lead screw or driven shaft is d2. Select the variant whose d1 × d2 combination matches those measurements. If one shaft is metric and the other is imperial (e.g., 1/4 in = 6.35 mm), choose the mixed-bore variant accordingly.
The outer diameter (D) should be compatible with the clearance around your motor face and mounting bracket. Larger D values generally support higher torque. The length (L) affects how much axial misalignment the coupler can absorb — longer couplers offer slightly more flexibility. Match the D × L to your motor frame size: D14–D20 suits NEMA 17, D25–D30 suits NEMA 23, and D45 suits larger servo or stepper frames.
Yes. The polyurethane spider insert accommodates angular misalignment (typically up to 1°–3°), parallel offset, and minor axial displacement. It is not designed for large misalignments — always align shafts as closely as possible during installation to maximize coupler lifespan and minimize vibration.
Yes. The elastomer spider sits between the two aluminum hubs and can be removed and replaced independently. This is useful on high-duty-cycle machines where the spider may wear before the hubs do, saving cost on replacement parts.
Yes. Several variants include a 6.35 mm bore, which is the metric equivalent of 1/4 inch. Mixed-bore variants (e.g., 6.35 mm × 8 mm) allow you to connect an imperial motor shaft to a metric lead screw or vice versa. Check the variant list for the exact d1 × d2 combination you need.
A rigid coupler transmits torque with zero flex — any shaft misalignment creates bearing stress and vibration. A plum spider jaw coupler uses an elastomer insert to absorb misalignment and dampen vibration, making it far more forgiving in real-world CNC and 3D printer builds where perfect shaft alignment is difficult to achieve.
Slide each hub onto its respective shaft, position the spider insert between the hubs, then tighten the set screws on each hub to clamp the bore. Ensure the shaft ends are flush with or slightly recessed from the inner face of each hub for maximum grip. Use a hex key (Allen wrench) matching the set screw size. Re-check tightness after the first few hours of operation.
