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When misaligned shafts cause vibration, lost steps, or premature bearing wear, the root cause is often a poorly fitted coupling. Engineers, CNC builders, and 3D printer enthusiasts who demand repeatable positioning accuracy need a coupling that holds tight under continuous load without introducing play. This rigid flexible shaft coupling is engineered for exactly that — delivering firm, backlash-free torque transmission between motor and lead screw.
Each coupler is machined from aluminum alloy with an outer diameter of 20mm (0.79 in) and a body length of 25mm (0.98 in). The inner orifice (bore) is available in a range of sizes from 5mm to 10mm (0.20–0.39 in), covering both metric and imperial shaft diameters including 6.35mm (1/4 in) for compatibility with standard stepper motor shafts. Set screws on both ends lock each shaft independently for a secure, tool-adjustable grip.
Typical applications include NEMA 17 and NEMA 23 stepper motor assemblies in CNC routers, lead screw drives in 3D printers, and light-duty robotic joint actuators where rigid coupling between motor shaft and driven shaft is required. The D20×L25 form factor fits within compact motor mounts without requiring additional clearance.
Solid one-piece body with dual set-screw clamping eliminates rotational play, ensuring accurate positioning in CNC and 3D printing applications.
Available in 15 inner orifice combinations from 5×5mm to 10×10mm, including 6.35mm (1/4") for imperial stepper motor shafts — one listing covers most common setups.
Lightweight yet rigid aluminum alloy body resists deformation under torque load while keeping rotational inertia low for responsive motor control.
20mm outer diameter and 25mm length fit standard motor mount cutouts without modification, making drop-in replacement straightforward.
Separate set screws on each bore end allow independent tightening of motor shaft and lead screw, accommodating slight diameter differences between the two sides.
Designed to pair with NEMA 17 and NEMA 23 stepper motors commonly used in CNC routers, laser engravers, 3D printers, and light robotics platforms.
| Outer Diameter (D) | 20mm (0.79 in) |
|---|---|
| Body Length (L) | 25mm (0.98 in) |
| Inner Orifice (Bore) | 5×5mm to 10×10mm (see variant options) |
| Material | Aluminum alloy |
| Coupling Type | Rigid / Zero-backlash |
| Locking Method | Dual set screws (one per bore end) |
| Compatible Motor Types | NEMA 17, NEMA 23 stepper motors |
| Shaft Diameter Range | 5mm – 10mm (incl. 6.35mm / 1/4") |
| Weight | See variant options |
| Surface Finish | See variant options |
Measure both your stepper motor shaft diameter and your lead screw diameter. Select the variant where the first number matches your motor shaft and the second number matches your lead screw. For example, if your motor shaft is 5mm and your lead screw is 8mm, choose the 5×8mm variant. If you are unsure, use a digital caliper for an accurate measurement.
This rigid coupler is optimized for low-to-medium speed stepper motor applications such as CNC routers, 3D printers, and lead screw drives. It is not designed for high-RPM spindle or servo motor applications where flexible or jaw-type couplings are typically preferred.
As a rigid coupling, it does not compensate for angular or parallel misalignment. Both shafts should be as co-axial as possible before installation. If your application involves inherent misalignment, consider a flexible jaw or helical coupler instead.
Aluminum alloy offers good natural oxidation resistance for indoor and dry environments. For applications exposed to moisture, coolant mist (e.g., CNC with flood cooling), or corrosive atmospheres, additional protective measures or a stainless steel alternative may be advisable.
Yes. NEMA 17 stepper motors typically have a 5mm output shaft. Select any variant with a first bore dimension of 5mm (e.g., 5×5mm, 5×6mm, 5×8mm, or 5×10mm) depending on your lead screw diameter. The D20×L25 body fits standard NEMA 17 motor mounts without modification.
6.35mm is the metric equivalent of 1/4 inch, a common shaft diameter on imperial-spec stepper motors and some lead screws used in North American CNC kits. The 6.35mm variants allow direct compatibility without adapters or machining.
The set screws are typically M3 or M4 hex socket head screws tightened with an Allen (hex) key. Insert each shaft fully into its respective bore, then tighten the corresponding set screw firmly. Avoid over-tightening, which can deform soft shaft surfaces. Contact us to confirm the exact set screw size for your variant.
