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When a misaligned motor shaft causes vibration, lost steps, or premature bearing wear on your CNC router or 3D printer, the coupling is usually the first place to look. These flexible shaft couplings are designed for makers, machine builders, and automation engineers who need a dependable connection between a stepper motor shaft and a lead screw or ball screw — without the precision headaches of rigid couplings.
Each coupling is machined from aluminum alloy with a helical-cut flexible body that absorbs angular and parallel misalignment. The outer diameter is 20mm or 25mm (0.79" or 0.98"), with a body length of 25mm (0.98"). Bore sizes range from 3mm to 12mm (0.12" to 0.47") for d1 and d2, covering the most common stepper motor shaft and lead screw combinations. Two clamping styles are available: set screw type for quick installation, and clamp+set screw type for a more secure grip on smooth shafts.
Typical use cases include NEMA 17 and NEMA 23 stepper motor to T8 lead screw connections on DIY CNC machines, Z-axis couplings on FDM 3D printers such as Ender-series builds, and light-duty servo-to-shaft connections in automation rigs where flexible shaft coupling misalignment compensation is needed.
| Product Type | Flexible Shaft Coupling (Jaw / Helical-cut) |
|---|---|
| Clamping Style | Set screw type / Clamp+Set screw type |
| Outer Diameter (D) | 20mm (0.79") / 25mm (0.98") |
| Body Length (L) | 25mm (0.98") |
| Bore d1 Range | 3mm – 12mm (0.12" – 0.47") |
| Bore d2 Range | 3mm – 12mm (0.12" – 0.47") |
| Material | Aluminum Alloy |
| Finish | See variant options |
| Misalignment Compensation | Angular & parallel (helical-cut body) |
| Compatible Motor Types | NEMA 17, NEMA 23 stepper motors |
| Compatible Screw Types | T8, T10 lead screws; standard ball screws |
| Quantity per Order | 1 Pcs or 10 Pcs (see variant options) |
Measure your stepper motor output shaft diameter (d1) and your lead screw or ball screw shaft diameter (d2). Select the variant that matches both values — for example, if your NEMA 17 motor has a 5mm shaft and your T8 lead screw has a 8mm shaft, choose the "5mm × 8mm" bore option. Mixed bore sizes are fully supported across the range.
The set screw type uses grub screws that press directly against the shaft — fast to install and suitable for shafts with a flat (D-cut). The clamp+set screw type adds a split-clamp collar that wraps around the shaft for a more secure, slip-resistant grip, which is recommended for smooth round shafts or higher-torque applications.
The D25mm×L25mm variants are sized for NEMA 23 motors. The aluminum helical body is designed for the torque range typical of NEMA 23 stepper motors in CNC and light automation use. For very high-torque or continuous-duty industrial applications, contact us to confirm suitability before ordering.
The helical-cut flexible body compensates for small angular and parallel misalignment between the motor shaft and lead screw — typically up to a few degrees of angular offset and fractions of a millimeter of parallel offset. It is not designed for large misalignment; always align shafts as closely as possible during installation for best performance and coupling longevity.
Yes. The D20mm×L25mm set screw type with a 5mm×8mm bore is one of the most common configurations for Ender-series and similar FDM printers, where the NEMA 17 motor has a 5mm shaft and the T8 lead screw has an 8mm coupling end. Check your printer's specific shaft dimensions before ordering.
The 1-piece option is ideal for single-machine repairs or upgrades. The 10-piece pack offers a lower per-unit cost and is practical for batch CNC builds, multi-axis machines, or keeping spares on hand for a workshop. Both options are available across the full bore size range.
Aluminum alloy has natural oxidation resistance that provides reasonable protection in typical indoor workshop conditions. For environments with prolonged moisture exposure or chemical contact, consider applying a light machine oil to the coupling surface as a precaution. The set screws are steel and may show surface rust over time in very humid conditions.
