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Misaligned shafts and vibration-induced positioning errors are a constant headache for CNC builders, 3D printer engineers, and automation integrators. The D30L40 CNC Shaft Coupler is engineered for exactly these challenges — delivering reliable torque transmission with built-in flexibility that absorbs angular, parallel, and axial misalignment without stressing your motor bearings.
This jaw coupling set consists of two aluminum alloy hubs and a polyurethane spider insert (plum-type elastomer). The outer diameter is 30mm (1.18 in) and the overall length is 40mm (1.57 in). Bore diameters span 5mm to 16mm (0.20–0.63 in), with both same-bore and stepped-bore combinations available to suit mixed-shaft assemblies.
Typical use cases include NEMA 17/23 stepper motor to lead screw connections on CNC routers and laser engravers, servo motor shaft coupling on pick-and-place automation rigs, and encoder shaft linking on precision measurement equipment — all scenarios where a flexible jaw shaft coupler for stepper motors reduces resonance and extends component life.
Machined aluminum hubs deliver low rotational inertia and corrosion resistance, keeping coupling weight minimal while maintaining structural rigidity under continuous torque loads.
The plum-type elastomer spider absorbs shock, dampens vibration, and accommodates angular misalignment up to approximately 1°, parallel offset up to ~0.2mm, and axial displacement — protecting motor bearings from side-load stress.
Available in 90 shaft diameter combinations — same-bore (e.g., 8mm × 8mm) and stepped-bore (e.g., 6mm × 10mm) — making this coupler compatible with a broad range of CNC, 3D printing, and automation shaft pairings.
Each hub is secured via radial set screws for tool-free shaft swaps during prototyping. Tighten with a standard hex key for a firm, slip-resistant grip on both smooth and flat-keyed shafts.
The jaw-and-spider interface maintains near-zero backlash under normal CNC loads, preserving positional accuracy on lead screw and ball screw driven axes — critical for repeatable machining and printing results.
At 30mm OD and 40mm length, this coupler fits within tight motor-to-screw clearances common in compact CNC frames, desktop routers, and DIY automation enclosures without requiring spacer modifications.
| Coupling Type | Flexible Jaw / Plum Spider (Oldham-style elastomer) |
|---|---|
| Outer Diameter (OD) | 30mm (1.18 in) |
| Overall Length | 40mm (1.57 in) |
| Bore Diameter Range | 5mm – 16mm (0.20 – 0.63 in) |
| Shaft Diameter Combination | See variant options |
| Hub Material | Aluminum alloy (anodized) |
| Spider / Insert Material | Polyurethane elastomer |
| Clamping Method | Radial set screw (hex key) |
| Angular Misalignment Tolerance | Typically ≤ 1° |
| Parallel Offset Tolerance | Typically ≤ 0.2mm |
| Quantity per Order | 1 Pcs (complete coupling set: 2 hubs + 1 spider) |
| Weight | See variant options |
| Compatible Motor Types | Stepper motor, servo motor, encoder shaft |
Measure both shafts you need to connect — your motor output shaft and your lead screw or driven shaft — using a digital caliper. Select the variant that matches both diameters exactly (e.g., "8mm × 10mm" means one hub bores 8mm and the other bores 10mm). If both shafts are the same size, choose a same-bore option like "8mm × 8mm".
Yes. The 6.35mm bore variants are specifically sized for 1/4" imperial shafts, which are common on North American stepper motors and some servo motors. Look for any variant listing "6.35mm" on either side of the combination.
The polyurethane spider insert accommodates angular misalignment of approximately 1° and parallel (radial) offset of up to ~0.2mm. It also handles minor axial displacement. For best longevity, align shafts as closely as possible — the spider compensates for residual misalignment, not gross assembly errors.
This D30L40 jaw coupler is designed for the low-to-medium RPM range typical of CNC stepper and servo motor applications (generally under 3,000 RPM). For very high-speed spindle or motor applications, verify the dynamic balance requirements of your system before use.
Polyurethane spider inserts are wear components. Under normal CNC duty cycles they last a long time, but if you notice increased vibration, audible clicking, or visible cracking of the elastomer, the spider should be replaced. The two aluminum hubs are reusable — only the spider needs periodic replacement.
Yes, this is one of the most common applications. The flexible jaw design compensates for minor Z-axis motor-to-lead-screw misalignment that causes Z-banding artifacts in prints. Select the bore combination matching your motor shaft (typically 5mm for NEMA 17) and your lead screw diameter (typically 8mm for T8 screws).
Insert each shaft fully into its respective hub bore. Position the coupler so the spider insert sits centered between the two hubs. Using a hex key (Allen wrench), tighten the set screws firmly — do not overtighten, as this can deform the bore. For flat-keyed shafts, align the set screw over the flat before tightening for maximum grip.
