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When shaft misalignment causes vibration, noise, or premature wear in your CNC router, 3D printer, or stepper motor drive system, the coupling is often the first component to fail. Engineers and DIY builders who demand tight tolerances and smooth torque transmission need a coupling that absorbs angular and parallel misalignment without sacrificing rigidity. The D40L66 Aluminum Flexible Beam Helical/Spider Shaft Coupling is engineered for exactly that application.
This coupling features a one-piece aluminum alloy body (typically 6061-T6 grade) machined with a helical beam cut pattern that provides flexibility in all axes. The outer diameter is 40mm (approx. 1.57 in) and the overall length is 66mm (approx. 2.60 in). Bore sizes range from 6mm to 22mm (approx. 0.24–0.87 in) on both sides, with same-bore and stepped-bore combinations available across 153 variants. Clamping is achieved via set screws on each hub end.
Typical use cases include NEMA 17/23 stepper motor to lead screw connections on CNC mills and laser engravers, servo motor shaft coupling on pick-and-place machines, and encoder shaft coupling on precision measurement equipment where zero-backlash flexible beam coupling performance is required.
The single-body helical cut eliminates the need for a separate spider insert, reducing part count and maintaining consistent torque transmission without backlash.
Wide Bore Range: 6mm–22mmWith 153 shaft diameter combinations available (same-bore and stepped), this coupling covers the most common stepper motor and lead screw shaft sizes used in CNC and automation builds.
Aluminum Alloy ConstructionLightweight yet rigid aluminum alloy body (typically 6061-T6) keeps rotational inertia low — critical for high-acceleration stepper motor applications where added mass degrades step response.
Misalignment CompensationThe helical beam geometry accommodates angular misalignment (typically up to 1°), parallel offset, and axial displacement, protecting motor bearings and lead screw nuts from side-loading stress.
Set Screw Clamping on Both HubsEach hub end is secured with a set screw for tool-free shaft changes during prototyping or maintenance. Tighten to the shaft flat or keyway for a secure, slip-resistant connection.
Sold Individually (1 Pcs per Order)Each listing ships as a single coupling unit. Order the exact quantity you need for your build — no minimum bundle required.
| Outer Diameter (OD) | 40mm (1.57 in) |
|---|---|
| Overall Length | 66mm (2.60 in) |
| Bore Range (each side) | 6mm – 22mm (0.24 – 0.87 in) |
| Bore Combinations | Same-bore and stepped-bore; see variant options |
| Material | Aluminum alloy (typically 6061-T6) |
| Coupling Type | Helical beam (one-piece, zero-backlash) |
| Clamping Method | Set screw (both hub ends) |
| Angular Misalignment | Typically up to 1° |
| Finish | Natural anodized aluminum |
| Quantity per Order | 1 Pcs |
Measure the shaft diameter on your motor output and your lead screw or driven shaft separately. Select the variant that matches both diameters — for example, "8mm X 10mm" means the motor-side bore is 8mm and the driven-side bore is 10mm. If both shafts are the same diameter, choose a same-bore variant such as "10mm X 10mm".
A helical beam coupling is machined from a single piece of aluminum with spiral cuts that provide flexibility — there is no separate elastomeric spider insert. This gives it zero backlash and consistent stiffness over its service life. A jaw/spider coupling uses a replaceable polyurethane or rubber spider between two metal hubs, which can wear and introduce backlash over time. Helical beam couplings are preferred for closed-loop servo and precision CNC applications.
Yes. The helical beam geometry accommodates angular misalignment (typically up to 1°) and small amounts of parallel offset and axial displacement. However, for best performance and longest service life, align your shafts as closely as possible during installation. Excessive misalignment will increase stress on the coupling and reduce its fatigue life.
Yes. NEMA 17 motors typically have a 5mm output shaft, and NEMA 23 motors commonly use 6.35mm (1/4 in) or 8mm shafts. Select the bore variant that matches your motor shaft on one side and your lead screw or ball screw diameter on the other. The 40mm OD and 66mm length of this coupling are well-suited to both motor frame sizes.
Aluminum alloy has natural oxidation resistance and the anodized finish adds an additional protective layer against moisture and mild chemical exposure. For environments with heavy coolant spray (such as wet CNC machining), consider applying a light coat of machine oil to the coupling surface periodically. This coupling is not rated for submersion or highly corrosive chemical environments.
Slide each hub end onto the corresponding shaft until the shaft is fully seated in the bore. Align the set screw with the shaft flat or keyway if present, then tighten with the appropriate hex key. Do not overtighten — snug the set screw firmly until the coupling does not rotate independently on the shaft. For shafts without a flat, apply thread-locking compound to the set screw threads to prevent loosening under vibration.
Exact torque and RPM ratings depend on the specific bore size and operating conditions. As a general reference, D40 series helical beam couplings in this size class are typically rated for torques in the range of 3–8 Nm and speeds up to 3,000–5,000 RPM under normal operating conditions. Contact us to confirm specifications for your specific application if precise ratings are required.
