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When misalignment between a servomotor shaft and a lead screw causes vibration, lost steps, or premature bearing wear, the coupling is almost always the culprit. Engineers and machine builders who demand repeatable positioning accuracy need a coupling that transmits torque without play while still absorbing angular and parallel offset — that is exactly what this D34 double diaphragm design delivers.
Each coupling features a two-diaphragm flexible element sandwiched between precision-machined aluminum hubs. The outer diameter is 34 mm (1.34 in) and the body length is 45 mm (1.77 in). Bore combinations span φd1 × φd2 from 6 mm up to 14 mm on each side, covering both equal-bore and stepped-bore configurations. Set screws clamp each bore independently for secure shaft retention.
Typical applications include CNC router Z-axis ball-screw couplings, servo-driven linear actuator connections, laser engraver spindle drives, and 3D printer lead-screw flexible shaft couplings where zero backlash and torsional stiffness are non-negotiable.
| Coupling Type | Double Diaphragm Flexible Coupling |
|---|---|
| Outer Diameter (D) | 34 mm (1.34 in) |
| Body Length (L) | 45 mm (1.77 in) |
| Bore Diameter φd1 | 6 mm – 14 mm (see variant options) |
| Bore Diameter φd2 | 6 mm – 14 mm (see variant options) |
| Hub Material | Aluminum Alloy |
| Diaphragm Material | Stainless Steel |
| Backlash | Zero (rigid torsional transmission) |
| Angular Misalignment | Typically up to 1° |
| Parallel Offset | Typically up to 0.2 mm |
| Clamping Method | Set Screw (per hub) |
| Finish | See variant options |
| Quantity per Order | 1 / 2 / 3 / 5 / 10 pcs (see variant options) |
Measure the diameter of your motor output shaft (this becomes φd1) and the diameter of your lead screw or driven shaft (this becomes φd2). Select the variant that matches both values. If both shafts are the same diameter, choose an equal-bore variant (e.g., 8 mm × 8 mm). If they differ, choose the appropriate stepped-bore variant (e.g., 6 mm × 10 mm).
A double diaphragm coupling provides zero backlash and higher torsional stiffness than a jaw (spider) coupling, while still accommodating angular and parallel misalignment. Compared to a single diaphragm, the double diaphragm design handles greater angular misalignment and axial displacement without introducing bending moments into the motor bearings.
Yes. The lightweight aluminum hubs minimize rotational inertia, making this coupling well-suited for servo-driven axes and stepper-motor lead-screw assemblies where fast acceleration and deceleration are required. For very high-RPM spindle applications (above approximately 3,000 RPM), confirm dynamic balance requirements with your system specifications.
The aluminum alloy hubs offer good resistance to oxidation in typical workshop and indoor environments. The stainless-steel diaphragm elements provide additional corrosion resistance. For harsh environments involving coolant mist or high humidity, consider applying a light protective coating to the aluminum hubs.
Yes — the double diaphragm element is designed to compensate for small angular misalignment (typically up to 1°) and parallel offset (typically up to 0.2 mm). However, for best service life and accuracy, align shafts as closely as possible before installation. Excessive misalignment beyond the rated tolerance will reduce coupling life and may transmit unwanted loads to motor bearings.
Slide each hub onto its respective shaft until the shaft reaches the bottom of the bore. Tighten the set screw on each hub to the manufacturer's recommended torque using an appropriate hex key. Ensure the shaft surface is clean and free of oil before tightening. Do not over-tighten, as this may deform the bore or damage the shaft.
A typical 3-axis CNC router or laser engraver requires one coupling per driven axis, so a 3-piece order covers a full build. The 5-piece and 10-piece options offer a lower per-unit cost and provide spares for future maintenance or additional machine builds.
