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Two silver aluminium shaft couplings, 25mm diameter by 40mm long, set-screw clamping

Unique-Bargains

Unique-Bargains 6.35mm to 8mm Shaft Coupling 25mm x 40mm 2pcs

SKU CH-0H69-GDSHM

Two aluminium-alloy beam couplings join a 6.35 mm shaft to an 8 mm shaft with M4 set-screw clamping, 40 mm long by 25 mm diameter

  • Connects 6.35mm to 8mm shafts for flexible motor alignment
  • Aluminium alloy construction resists corrosion in CNC and 3D printer setups
  • Coiling clamp screw design absorbs angular and parallel misalignment
  • One-piece spring coupling transmits light torque with minimal backlash
  • Two couplers included for dual-axis or spare-part requirements

Shaft Coupling for 6.35mm to 8mm Motors

This aluminium-alloy coupler joins a 6.35mm shaft to an 8mm shaft using a set-screw clamping method. The one-piece beam design absorbs parallel and angular misalignment as well as shaft end-play through spring action. It is intended for light-to-medium torque drives in 3D-printer Z axes, small CNC encoders, lead screws and similar instrumentation. Two couplings are supplied in the pack.

Limits of the Beam-Coupling Design

The flexible beam transmits only low torque, so it suits small stepper or servo motors rather than high-power spindles. Excessive radial load or rapid acceleration can exceed the spring deflection range and cause permanent deformation. The M4 x 0.7 set screws provide axial holding force but rely on shaft hardness; soft shafts may slip under sudden reversal. No keyway or clamping collar is present, so pure torsional stiffness is limited.

Build Quality and Everyday Implications

Machined from silver-toned aluminium alloy, each coupling measures 40mm long by 25mm in diameter. The single-piece construction eliminates backlash between hubs and reduces part count during assembly. Set screws are accessed radially, allowing adjustment without removing the coupling from the shaft stack. The compact length keeps the overall drive train short, which helps in tight printer frames or encoder housings.

Highlights

  • Connects 6.35mm to 8mm shafts for flexible motor alignment
  • Aluminium alloy construction resists corrosion in CNC and 3D printer setups
  • Coiling clamp screw design absorbs angular and parallel misalignment
  • One-piece spring coupling transmits light torque with minimal backlash
  • Two couplers included for dual-axis or spare-part requirements

Specifications

BrandUnique Bargains

Questions about this item

Should I pick the 6.35 mm or the 8 mm bore for my motor shaft?

Each coupling has two different bores — one end is 6.35 mm and the other is 8 mm — so a single coupler joins those two shaft sizes together.

What does the 40 mm length mean once the coupling is installed?

The 40 mm overall length is the distance the coupling occupies between the two connected shafts, with 25 mm outside diameter.

How does the M4 × 0.7 set-screw clamping perform in practice?

Two M4 × 0.7 screws on each hub clamp the shafts by coiling action, holding light-to-medium torque loads while the metallic spring body absorbs parallel, angular and end-play misalignment.

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