Flexible Shaft Coupler 8mm x 10mm - Aluminum Helical Coupling for CNC

Specifications

• Bore A (Motor Side): 8mm

• Bore B (Screw Side): 10mm

• Material: Aluminum Alloy (Anodized)

• Coupling Type: Helical Beam (Clamp or Set Screw type - Standard is Set Screw)

• Flexibility: Angular (up to 2°), Parallel (up to 0.2mm), Axial (Spring action)

• Outer Diameter (OD): 19mm (Standard) or 25mm for Heavy Duty batches

• Length (L): 25mm (Standard) or 30mm

• Fastening: 4 x Grub Screws (Included)

• Torque Rating: Suitable for NEMA 23 Stepper Motors

Key Applications & Projects

• CNC Routers: Connecting the main drive motors to 10mm Ball Screws (SFU1204/1605).

• Heavy-Duty 3D Printers: Z-axis upgrades for larger format printers using 10mm lead screws.

• Robotic Arms: Joint actuation where the motor shaft and gearbox input shaft are different sizes.

• Pick and Place Machines: High-speed axis coupling.

Virtual Technician: Installation Tips ⚠️

• The "Gap" Rule: When installing, do not let the two shafts touch inside the coupler. Leave a 2-3mm gap in the center. This allows the spiral spring section to flex freely. If the shafts touch, the coupler becomes rigid and loses its protective properties.

• Tightening Sequence: Tighten the set screws on the motor shaft first, then rotate the screw shaft to align, and tighten the second side. Use a thread-locker (like Blue Loctite) on the grub screws if your machine has high vibration.

• Tool Required: You will need a 2mm or 2.5mm Allen Key (Hex Wrench) to tighten the grub screws.

Accessories

• Included: 1xFlexible Shaft Coupler 8mm x 10mm,  4 x Grub Screws (Pre-installed).

• Required (Sold Separately):

  • 2mm Allen Key

  • NEMA 23 Stepper Motor (8mm Shaft)

  • 10mm Linear Shaft or Ball Screw

Frequently Asked Questions (FAQ)

1. What is the purpose of the spiral cut?

   • The spiral cut creates a "spring" effect that allows the coupler to bend slightly. This absorbs misalignment between the motor and the screw, preventing binding and reducing noise.

2. Does this introduce backlash?

   • No. This design is torsionally rigid, meaning when the motor turns 1 degree, the screw turns 1 degree. There is no "lag" in rotation, making it zero-backlash.

3. Can I use this to connect a 5mm motor shaft?

   • No, the hole is 8mm. A 5mm shaft will be too loose and will wobble. You need a 5mm to 10mm coupler for that.

4. Is this strong enough for a CNC router?

   • Yes, it is standard for light-to-medium duty CNC routers (using NEMA 23 motors). For very heavy industrial mills (NEMA 34), you might need "Jaw Couplers" (Spider couplers).

5. What happens if my shafts are perfectly aligned?

   • Even better! The coupler will simply act as a solid connector. However, perfect alignment is rare in DIY builds, so the protection is always useful.

6. Can I drill out the 8mm side to 9mm?

   • It is not recommended. The walls are thin, and drilling it manually will ruin the concentricity, causing vibration.

7. What size Allen key do I need?

   • Typically a 2mm Allen key for the M3/M4 grub screws.

8. Does it come with the screws?

   • Yes, it comes with 4 grub screws pre-installed.

9. Can this pull a heavy load?

   • These couplers are designed for Torque (twisting), not Tension (pulling apart). Do not use them to "hang" a heavy load; the spiral might stretch. The load should be supported by bearings.

10. Why did my coupler snap in half?

    • This usually happens if the machine "crashed" (hit a hard stop) or if the misalignment was too extreme (>5 degrees). It acts as a mechanical fuse to save your motor.

11. Is it made of steel or aluminum?

    • Aluminum Alloy. This keeps the rotating mass low (low inertia), allowing the motor to accelerate faster.

12. Can I use this on a round shaft vs a D-shaft?

    • Yes, it works on both. For round shafts, tighten the screws firmly. For D-shafts, align one screw with the flat spot.

13. What is the maximum speed?

    • They are balanced for stepper motor speeds (up to 1000-2000 RPM).

14. Is it better than a rigid flange coupling?

    • For motion control, Yes. Rigid couplings transfer all vibrations to the motor, which can ruin the internal bearings.

15. Will it fit a NEMA 17 motor?

    • Only if your NEMA 17 has an 8mm shaft (rare). Standard NEMA 17s have 5mm shafts.

16. Is it suitable for 3D printer Z-axis?

    • Yes, if you are using a thicker 10mm lead screw for stability.

17. How much misalignment can it handle?

    • Angular: ~1.5 to 2 degrees. Parallel: ~0.2mm.

18. Does it act as a heat insulator?

    • Slightly, due to the air gap in the spiral, but aluminum is conductive. If you need thermal isolation, use a plastic/nylon coupler.

19. What is the "Zero Backlash" feature?

    • It means there is no "play" or "slop" when changing direction. Essential for printing accurate circles.

20. Can I use thread locker on the screws?

    • Highly recommended! Vibration from stepper motors can loosen screws over time. Blue Loctite is best.