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When servo motor misalignment causes vibration, lost steps, or premature bearing wear, the coupling is often the first component to blame. Engineers and CNC builders who need a rigid yet forgiving connection between motor and leadscrew rely on double diaphragm couplings to absorb angular, parallel, and axial misalignment without introducing backlash. This D68 double diaphragm CNC shaft coupling is designed for demanding motion control applications where precision and durability are non-negotiable.
This coupling features an aluminium alloy body with an outer diameter of 68 mm (≈ 2.68 in) and a body length of 74 mm (≈ 2.91 in). The double diaphragm design uses two flexible stainless steel diaphragm discs to transmit torque while accommodating misalignment. Bore sizes range from d12 mm to d35 mm (≈ 0.47 in to 1.38 in) on both sides — select matching or mixed bore combinations from the variant options above.
Typical use cases include CNC router and milling machine Z-axis leadscrew connections, servo and stepper motor couplings in 3D printer gantry systems, and precision rotary encoder shaft connections in industrial automation. Long-tail search terms: aluminium double diaphragm servo coupler D68, zero-backlash CNC shaft coupling 68mm OD, flexible diaphragm coupling for servo motor bore 12–35mm.
Two stainless steel diaphragm discs transmit torque with no play, maintaining positional accuracy in CNC and servo applications.
Supports same-bore and mixed-bore configurations across 250+ variant combinations, covering the most common servo and stepper motor shaft sizes.
Lightweight yet rigid aluminium construction reduces rotational inertia while maintaining structural integrity under continuous cyclic loading.
Accommodates angular, parallel, and axial misalignment between motor and driven shaft, reducing stress on bearings and motor output shafts.
68 mm outer diameter and 74 mm body length fit standard servo motor mounting envelopes without requiring custom spacers or adapters.
Split-clamp or set-screw bore fixation (see variant options) ensures secure shaft engagement without damaging shaft surfaces during installation or removal.
| Outer Diameter (OD) | 68 mm (≈ 2.68 in) |
|---|---|
| Body Length (L) | 74 mm (≈ 2.91 in) |
| Bore Size Range (d1 / d2) | 12 mm – 35 mm (≈ 0.47 – 1.38 in) |
| Bore Configuration | Same-bore or mixed-bore (select variant) |
| Coupling Type | Double Diaphragm |
| Body Material | Aluminium Alloy |
| Diaphragm Material | Stainless Steel |
| Backlash | Zero (rigid torque path) |
| Misalignment Tolerance | See variant options |
| Max Torque | See variant options |
| Application | CNC, servo motor, stepper motor, encoder |
| Quantity per Order | 1 pc |
Measure the shaft diameter of your motor output shaft (d1) and the shaft diameter of your leadscrew or driven component (d2) using a digital caliper. Select the variant that matches both measurements. If both shafts are the same diameter, choose a same-bore variant (e.g., d15–d15). If they differ, choose a mixed-bore variant (e.g., d15–d20). Bore sizes range from 12 mm to 35 mm on each side.
A double diaphragm coupling uses two thin, flexible stainless steel discs to transmit torque between two shafts. Unlike jaw or bellows couplings, the double diaphragm design provides zero backlash while tolerating angular, parallel, and axial misalignment simultaneously. This makes it well-suited for servo motor and CNC leadscrew connections where positional accuracy and smooth torque transmission are critical.
The D68 aluminium double diaphragm coupling is designed for servo and stepper motor applications in the light-to-medium duty range typical of CNC routers, 3D printers, and small industrial machines. For specific torque ratings, please contact us to confirm compatibility with your motor's rated and peak torque output before ordering.
The aluminium alloy body offers good natural corrosion resistance for typical indoor workshop environments. The stainless steel diaphragm discs provide additional corrosion resistance. For high-humidity, chemical-exposure, or outdoor environments, consider applying a protective coating or contact us to discuss material options.
Yes. The double diaphragm design is specifically engineered to accommodate angular, parallel (radial), and axial misalignment between the two connected shafts. However, excessive misalignment beyond the coupling's rated tolerance will reduce service life and may cause vibration. Aim for the best possible alignment during installation to maximize coupling longevity.
The bore fixation method (set screw or split clamp) depends on the specific variant. Clamp-style fixation is generally preferred for servo applications as it distributes clamping force evenly around the shaft without risking shaft surface damage. Please refer to the variant details or contact us to confirm the fixation type for your selected bore combination.
The D68 outer diameter allows for larger bore sizes (up to 35 mm) and generally supports higher torque transmission compared to smaller OD couplings such as D32 or D40 variants. Choose D68 when your motor or leadscrew shaft diameter exceeds the bore capacity of smaller couplings, or when your application requires higher torque handling within the double diaphragm coupling family.
