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When misalignment between a servo motor and a lead screw causes vibration, premature bearing wear, or positioning errors, the coupling is often the first component to blame. Engineers and machine builders working on CNC routers, 3D printers, laser engravers, and precision linear stages need a coupling that absorbs angular and axial misalignment without sacrificing torque transmission accuracy. These single diaphragm shaft couplings are designed for exactly that application.
Each coupling is machined from aluminum alloy with a stainless steel diaphragm element. Two outer diameter options are available: D19 × L19 mm (≈ 0.75 × 0.75 in) and D26 × L26 mm (≈ 1.02 × 1.02 in). Bore sizes range from 4 mm to 10 mm on both sides (d1 and d2), selectable independently to accommodate mixed shaft diameters. Clamping is achieved via split-clamp collar design for secure, backlash-free shaft grip.
Typical use cases include servo-to-ballscrew connections on CNC milling machines, stepper motor shaft couplings for 3D printer Z-axis drives, and encoder shaft couplings for precision rotary feedback systems. The single diaphragm design provides zero-backlash torque transmission while accommodating slight parallel and angular misalignment — a common requirement in flexible shaft coupling for CNC applications.
| Coupling Type | Single Diaphragm Flexible Shaft Coupling |
|---|---|
| Body Material | Aluminum Alloy |
| Diaphragm Material | Stainless Steel |
| Outer Diameter (OD) Options | D19 mm / D26 mm |
| Length (L) Options | L19 mm / L26 mm |
| Bore Size d1 Range | 4 mm – 10 mm (see variant options) |
| Bore Size d2 Range | 4 mm – 10 mm (see variant options) |
| Bore Combination | d1 and d2 independently selectable |
| Retention Method | Split-Clamp with Radial Clamping Screws |
| Backlash | Zero (diaphragm design) |
| Misalignment Compensation | Angular and Axial |
| Finish | See variant options |
| Quantity per Order | 1 / 2 / 3 / 5 / 10 pcs (selectable) |
The D19 × L19 mm coupling is suited for compact motors such as NEMA 17 servos and small stepper motors with shaft diameters of 4–8 mm. The D26 × L26 mm coupling handles higher torque applications including NEMA 23 and NEMA 34 motors with shaft diameters up to 10 mm. If your motor and driven shaft are both under 8 mm, D19 is typically sufficient. For shafts 8 mm and above, or where higher torque is involved, select D26.
Yes. The d1 and d2 bore sizes are independently selectable. For example, you can pair a 5 mm motor shaft (d1 = 5 mm) with an 8 mm ballscrew shaft (d2 = 8 mm) in a single coupling. Select the variant that matches your specific d1 × d2 combination from the dropdown menu.
Yes. The single diaphragm design transmits torque through a thin stainless steel disc rather than jaw inserts or spider elements, which eliminates the clearance gaps that cause backlash. This makes it suitable for closed-loop servo systems where positional accuracy is critical, such as CNC axes and encoder feedback shafts.
Single diaphragm couplings typically accommodate angular misalignment of approximately 1°–3° and axial displacement of 0.1–0.5 mm depending on the diaphragm stiffness and coupling size. They are not designed for large parallel (radial) misalignment. For best results, align shafts as accurately as possible during installation and use the coupling to absorb residual misalignment only.
The split-clamp collar design applies radial clamping force evenly around the shaft circumference, unlike set-screw designs that concentrate force at a single point. This significantly reduces the risk of shaft damage and allows the coupling to be repositioned or removed without leaving permanent marks, making it suitable for repeated assembly and disassembly.
The aluminum alloy body provides moderate corrosion resistance suitable for indoor workshop and light industrial environments. The stainless steel diaphragm element offers good resistance to oxidation. For highly corrosive or wet environments, additional protective measures such as periodic lubrication of clamping screws or protective coatings may be advisable.
A single diaphragm coupling uses one flexible disc and is more compact and cost-effective, handling angular and axial misalignment well. A double diaphragm coupling uses two discs connected by a spacer and can additionally accommodate parallel (radial) misalignment. For most servo and stepper motor CNC applications where shafts are well-aligned, a single diaphragm coupling is the standard choice.
