Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
When misalignment between a servo motor 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 zero-backlash torque transmission need a coupling that compensates for angular and axial misalignment without sacrificing rigidity. This D39 single diaphragm shaft coupling is designed for exactly that application.
Each coupling is machined from aluminium alloy and features a single diaphragm flexible element. The outer diameter is 39 mm (≈1.54 in) and the body length is 34 mm (≈1.34 in). Bore sizes d1 and d2 are independently selectable from 8 mm to 19 mm (≈0.31–0.75 in), covering the most common servo motor shaft and lead screw shaft diameters in this class.
Typical applications include CNC router Z-axis couplings, servo-to-ballscrew connections on milling machines, stepper motor shaft couplings for 3D printer lead screws, and rotary encoder shaft adapters where torsional stiffness and low inertia are both required.
| Coupling Type | Single Diaphragm Flexible |
|---|---|
| Material | Aluminium Alloy |
| Outer Diameter (OD) | 39 mm (≈1.54 in) |
| Body Length (L) | 34 mm (≈1.34 in) |
| Bore d1 Range | 8–19 mm (≈0.31–0.75 in) |
| Bore d2 Range | 8–19 mm (≈0.31–0.75 in) |
| Bore Combination | See variant options |
| Backlash | See variant options |
| Max Torque | See variant options |
| Finish | Natural aluminium / anodised (see variant options) |
| Quantity per Pack | 1 pcs / 2 pcs / 3 pcs (select above) |
Measure the shaft diameter on your motor (d1) and the shaft diameter on your lead screw or driven component (d2) using a digital caliper. Select the variant that matches both measurements exactly. The bore sizes range from 8 mm to 19 mm on each end and can be different — for example, d1 = 10 mm and d2 = 12 mm is a valid combination.
A single diaphragm coupling uses one flexible disc element and is torsionally stiffer, making it well-suited for servo and stepper motor applications where positional accuracy matters. A double diaphragm coupling uses two discs and can accommodate greater angular misalignment, but at the cost of slightly lower torsional stiffness. For most CNC and servo applications, the single diaphragm design is the preferred choice.
This coupling is designed for servo and stepper motor shaft connections in CNC and automation equipment, typically operating at moderate speeds. For high-speed spindle applications (above approximately 5,000 RPM), please contact us to confirm suitability, as dynamic balancing requirements may differ.
Aluminium alloy forms a natural oxide layer that provides good resistance to atmospheric corrosion and light coolant exposure. For environments with continuous immersion in cutting fluids or aggressive chemicals, consider applying a protective coating or contact us to confirm compatibility with your specific coolant chemistry.
Yes. Many variants are available with equal bore sizes on both ends — for example, d1 = d2 = 10 mm. Simply select the variant where both bore values match your shaft diameter. These are listed alongside the mixed-bore variants in the size selector above.
Single diaphragm couplings of this type are typically secured using clamping screws (set screws or split-clamp design, depending on the specific variant). Insert each shaft end to the correct depth, align the coupling concentrically, and tighten the clamping screws to the manufacturer's specified torque. Ensure both shafts are clean and free of burrs before installation. If you need specific torque values, contact us to confirm for your variant.
Ordering 2 or 3 pieces at once is cost-effective if you are building multiple machine axes, want a spare on hand for rapid maintenance, or are prototyping and expect to test different bore combinations. The per-unit price is lower in multi-pack quantities compared to ordering singles separately.
