Aluminium NEMA17/775 (5mm x 5mm) Rigid Coupling

Specification	Details
Inner Diameter (Side A)	5 mm
Inner Diameter (Side B)	5 mm
Material	High-Grade Aluminium Alloy
Coupler Type	Rigid (Non-Flexible)
Length	~25 mm
Outer Diameter	~14 mm

Price

₹ 33.90

(Tax included)

Barcode: 643883

Product Description

The Aluminium NEMA17/775 Rigid Coupling is a precision-machined mechanical hardware designed to create a solid, zero-slip connection between two 5mm shafts. This coupler is the standard choice for connecting a NEMA17 stepper motor or a 775 DC motor directly to a 5mm lead screw or drive shaft. Unlike flexible couplings, this rigid version provides maximum torque transfer and high-precision alignment, making it ideal for CNC machines and 3D printers where "backlash" or "springiness" must be completely eliminated. Constructed from lightweight yet durable aluminium, it features four M4 set screws (grub screws) to ensure a high-friction grip that won't loosen under high-speed rotation or heavy mechanical loads.

Key Features

Zero Backlash: The solid one-piece construction ensures that every rotation of the motor is perfectly mirrored by the driven shaft, critical for high-precision motion control.
High Torque Transmission: Capable of handling significantly more load than flexible or spider couplings without deforming or slipping.
Corrosion Resistant: The anodized or natural aluminium finish protects the coupler from oxidation and environmental wear in industrial or workshop settings.
Lightweight Design: Reduces the rotational inertia of the motor system, allowing for faster acceleration and deceleration in automated machinery.
Secure Quad-Screw Locking: Features two grub screws per side (90-degree offset) to provide a balanced and firm grip on both the motor and the driven shaft.

Technical Details

Fastener Type: M4 Grub Screws (Requires 2mm Allen Key).
Bore Surface: Smooth precision-drilled bore.
Weight: ~15g to 20g.

Prototyping and Engineering Tips from Robogears

Alignment is Mandatory: CRITICAL: Because this is a Rigid coupling, the motor shaft and the driven shaft must be perfectly aligned (collinear). If there is even a slight offset or angle between the two shafts, a rigid coupler will put immense stress on the motor bearings, leading to premature motor failure or vibration. If your alignment isn't perfect, consider using a "Flexible/Plum" coupling instead.
The "Flat" Spot Rule: For the most secure connection, ensure that the grub screws sit on the "Flat" part of the D-shaped motor shaft. If your shaft is perfectly round, we recommend filing a small flat spot where the screw will land. This prevents the coupler from spinning freely on the shaft under heavy load.
Thread Locker (Loctite): In high-vibration environments (like CNC routers), the small grub screws can vibrate loose over time. Apply a tiny drop of Blue Thread Locker to the M4 screws before final tightening to ensure the connection remains permanent.
Cleaning the Shafts: Before installation, use Isopropyl Alcohol (IPA) to clean any oil or grease off the motor shaft and the inside of the coupler bore. Friction is the only thing holding these together; any lubricant will cause the coupler to slip.
Testing for Runout: After installation, spin the motor slowly and watch for any "wobble" (runout). If the driven shaft is wobbling, loosen the screws, realign the motor mount, and retighten. A wobbling shaft at 3000 RPM can cause catastrophic mechanical damage to your project frame.

Package Includes

1 x Aluminium Rigid Coupling (5mm x 5mm)
4 x M4 Grub Screws

Disclaimer: Do not use this coupling if your shafts are not perfectly aligned; the resulting stress can snap motor shafts or destroy bearings. Ensure the grub screws are tightened evenly on both sides to maintain balance. Keep fingers and loose clothing away from the coupling during high-speed operation. Use the correct sized Allen key to avoid stripping the grub screw heads.