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When a misaligned or slipping shaft coupling causes your CNC router to lose steps or your 3D printer to produce layer shifts, the root cause is almost always a poorly fitted coupler. These rigid flexible shaft couplings are engineered for makers, machine builders, and motion-control enthusiasts who need a dependable, zero-backlash connection between motor shafts and lead screws.
Each coupling is machined from aluminum alloy with a helical-cut flexible body, offering outer diameters from 15 mm (0.59 in) to 25 mm (0.98 in) and lengths from 20 mm (0.79 in) to 25 mm (0.98 in). Bore hole combinations (d1 × d2) span 2 mm up to 12 mm, covering the most common NEMA 17 and NEMA 23 stepper motor shaft sizes as well as standard metric and imperial lead-screw diameters.
Typical applications include CNC router Z-axis lead-screw connections, 3D printer Z-axis motor couplers, laser engraver feed-axis assemblies, and DIY linear actuator builds where shaft-to-shaft alignment is critical for long-term accuracy.
Helical-cut body absorbs minor angular and parallel misalignment while maintaining a rigid torque path, eliminating the backlash that causes positioning errors in CNC and 3D-printing applications.
Available in outer diameters D15, D16, D18, D19, D20, and D25 mm with lengths of 20, 23, and 25 mm. Bore combinations cover 2 mm through 12 mm on both sides, accommodating mixed metric and imperial shaft pairings.
Machined from lightweight aluminum alloy for a favorable strength-to-weight ratio. Naturally resistant to corrosion in typical workshop and indoor machine environments.
Dual set-screw design on each bore end locks securely onto motor shafts and lead screws without requiring adhesive or press-fit tooling, making installation and shaft swaps straightforward.
Balanced machining keeps vibration low at typical stepper motor RPM ranges, supporting smooth motion in 3D printers, CNC routers, and laser engravers running continuous duty cycles.
Standard outer-diameter sizing matches common coupler mounting pockets. Select the correct D × L and d1 × d2 combination from the variant selector to get a direct fit for your machine.
| Product Type | Rigid Flexible Shaft Coupling (Helical) |
|---|---|
| Material | Aluminum Alloy |
| Outer Diameter (D) | 15 / 16 / 18 / 19 / 20 / 25 mm |
| Length (L) | 20 / 23 / 25 mm |
| Bore d1 Range | 2 – 12 mm |
| Bore d2 Range | 2 – 12 mm |
| Bore Combination (d1 × d2) | See variant options |
| Clamping Method | Set screw |
| Finish | Natural aluminum (uncoated) |
| Typical Application | CNC router, 3D printer Z-axis, laser engraver, linear actuator |
| Compatible Motor Types | NEMA 17, NEMA 23 stepper motors |
| Weight per Unit | See variant options |
| Units per Order | 1 pc (select quantity variant for multi-pack) |
Measure the diameter of your motor shaft (d1) and your lead screw or driven shaft (d2) with a caliper. Then select the variant that matches both measurements. Common pairings for NEMA 17 printers are 5 mm × 5 mm or 5 mm × 8 mm. CNC routers with NEMA 23 motors often use 6.35 mm × 8 mm or 8 mm × 8 mm.
The outer diameter (D) determines how much radial space the coupling occupies — larger D values provide more torsional stiffness. The length (L) affects how much angular misalignment the helical cut can absorb; longer couplings tolerate slightly more misalignment. Choose based on the clearance available in your machine frame and the alignment quality of your motor mount.
Yes. The bore options include both metric sizes (2, 3, 4, 5, 6, 7, 8, 10, 12 mm) and imperial-equivalent sizes (3.17 mm ≈ 1/8 in, 6.35 mm = 1/4 in). Mixed pairings such as 5 mm × 6.35 mm are available in the variant list, making these couplings suitable for machines that combine metric motors with imperial lead screws.
"Rigid flexible" refers to the helical-cut design: the coupling body is machined from a single piece of aluminum with a spiral slot that gives it a small degree of flexibility to absorb angular and parallel shaft misalignment, while still transmitting torque with near-zero backlash. It is not a jaw-type or spider coupling — there is no elastomeric insert. This makes it stiffer and more precise than jaw couplings, but it requires reasonably good shaft alignment (typically within 1° angular and 0.2 mm parallel offset).
Aluminum alloy naturally forms a thin oxide layer that resists corrosion in typical indoor workshop environments. These couplings are suitable for dry or lightly oiled conditions. They are not recommended for continuous exposure to water, salt spray, or aggressive chemicals without additional surface treatment.
Slide one bore end onto the motor shaft and the other onto the lead screw. Align the shafts as closely as possible — the coupling can compensate for minor misalignment but is not a substitute for proper motor mounting. Tighten the set screws with an appropriate hex key (typically 1.5–2.5 mm depending on the bore size). Torque the set screws firmly but avoid over-tightening, which can deform the bore or strip the threads.
Yes. These couplings are widely used on 3D printer Z-axis assemblies (connecting the stepper motor to the lead screw) and on CNC router Z-axis and feed-axis drives. They are also suitable for laser engravers, plasma table drives, and custom linear actuator builds. Select the bore combination that matches your specific motor shaft and lead-screw diameters.
