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When misalignment between a servomotor shaft and a driven component causes vibration, premature bearing wear, or positioning errors, the root cause is often an inadequate coupling. Engineers and machine builders working on CNC routers, laser engravers, 3D printers, and robotic actuators need a coupling that absorbs angular and axial misalignment without sacrificing torque transmission accuracy.
This single diaphragm flexible shaft coupling features an aluminium alloy body with an outer diameter of 44 mm (≈1.73 in) and a body length of 35 mm (≈1.38 in). The bore diameter d1 and d2 are selectable from 8 mm up to 22 mm (≈0.31–0.87 in), covering a wide range of motor and lead-screw shaft combinations. The diaphragm element provides zero-backlash torque transmission while accommodating angular misalignment typically up to 1°–3° and axial displacement of approximately 0.2–0.5 mm.
Typical use cases include connecting NEMA 23/34 servomotor shafts to ball-screw assemblies in CNC milling machines, coupling encoder shafts in precision measurement equipment, and linking stepper motors to lead screws in desktop automation rigs — all scenarios where backlash-free, low-inertia power transmission is critical.
| Coupling Type | Single Diaphragm Flexible |
|---|---|
| Body Material | Aluminium Alloy |
| Outer Diameter (OD) | 44 mm (≈1.73 in) |
| Body Length | 35 mm (≈1.38 in) |
| Bore Diameter d1 | 8–22 mm (see variant options) |
| Bore Diameter d2 | 8–22 mm (see variant options) |
| Angular Misalignment | Typically 1°–3° |
| Axial Displacement | Typically 0.2–0.5 mm |
| Backlash | Zero (diaphragm element) |
| Fixing Method | Clamp-style split collar |
| Quantity per Pack | 1 pcs or 3 pcs (see variant options) |
| Surface Finish | See variant options |
| Max. Recommended RPM | See variant options |
| Rated Torque | See variant options |
Measure the outer diameter of both shafts you need to connect — your motor shaft (d1) and your driven shaft (d2). Select the variant that matches those two diameters. If both shafts are the same size, choose a same-bore variant (e.g., d10–d10). If they differ, choose the appropriate mixed-bore variant (e.g., d10–d14). Use a digital caliper for accurate measurement before ordering.
A single diaphragm coupling offers zero backlash and high torsional stiffness, making it well-suited for servo and stepper motor applications where positioning accuracy matters. Unlike jaw couplings, there is no elastomeric spider element to wear out or introduce compliance. Compared to bellows couplings, single diaphragm designs typically handle higher torque at the same diameter while remaining compact.
Yes. The diaphragm flexing element accommodates angular misalignment (typically up to 1°–3°) and axial displacement (typically 0.2–0.5 mm) simultaneously. However, operating at the limits of both simultaneously reduces coupling service life. For best results, align shafts as accurately as possible during installation and use the coupling's misalignment capacity as a tolerance buffer, not a primary alignment correction method.
NEMA 23 motors typically have 6.35 mm or 8 mm output shafts, and NEMA 34 motors commonly use 12.7 mm or 14 mm shafts — all within the 8–22 mm bore range of this coupling. Confirm your specific motor's shaft diameter from its datasheet before selecting a variant. This coupling is also compatible with lead screws, ball screws, and encoder shafts within the same bore range.
Aluminium alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in dry indoor workshop environments. For applications involving coolant mist, high humidity, or occasional water exposure, consider applying a light coating of machine oil to the coupling surface. For fully outdoor or submerged applications, a stainless steel coupling would be more appropriate.
The 1-piece pack is ideal for single-axis builds, prototyping, or replacing a worn coupling on an existing machine. The 3-piece pack offers a lower per-unit cost and is practical for multi-axis CNC machines (e.g., X, Y, Z axes each requiring one coupling), production runs, or keeping spares on hand to minimise downtime during maintenance.
Installation requires a hex key (Allen wrench) sized to the clamp collar screws — typically M3 or M4 depending on the variant. Insert both shafts to the correct depth (typically flush with or slightly past the diaphragm centre), align the shafts, then tighten the clamp screws to the recommended torque. No press-fit tools or special equipment are required for standard installations.
