
Overview
This rigid hex shaft coupling connects a matching motor shaft to a suitable 12 mm hex wheel hub or mechanism. The brass body is available in 18 mm standard and 30 mm extended lengths. Select the bore diameter and length independently; only actual available combinations are offered.
Features
- Rigid brass construction with a hexagonal drive end.
- Five bore diameters in the 18 mm version and four in the 30 mm version.
- M 4 radial set-screw fixing references and an M 4 threaded hex-face reference.
- Each coupling includes two fixing set screws and one hex key.
Specifications
| Product | Rigid brass hex shaft coupling / wheel adapter |
| Material | Brass; custom aluminum/steel manufacturing offers are not included retail options |
| Length choices | 18 mm standard or 30 mm extended |
| 18 mm bore choices | 2, 3, 4, 6 or 8 mm |
| 30 mm bore choices | 3, 4, 6 or 8 mm; no 2 mm extended option |
| Hex dimensions | 12 mm across flats; 13.75 mm across corners reference |
| Round body diameter | 11.5 mm reference |
| Radial fixing | M 4 opposed/through radial threaded-hole reference for set-screw fastening |
| Hex-face thread | M 4 axial threaded hole reference; confirm mating fastener engagement |
| Package | One selected coupling, two fixing set screws and one hex key |
| Not included | Motor, wheel, gearbox and complete mechanism; no axial wheel bolt specified |
| Ratings | No torque, speed, runout or bore tolerance rating specified |
Size Selection
| Bore diameter | Available lengths |
| 2 mm | 18 mm only |
| 3 mm | 18 mm or 30 mm |
| 4 mm | 18 mm or 30 mm |
| 6 mm | 18 mm or 30 mm |
| 8 mm | 18 mm or 30 mm |
The bore must match the actual shaft. The 12 mm across-flat hex dimension is a fit reference, not a guarantee of compatibility with every hex wheel. Check hub depth, shaft engagement, axial screw access and surrounding clearances before assembly. The 30 mm version provides additional reach; usable shaft insertion depth is not specified.
Installation
Slide the matching bore onto the shaft, align the hex end with the mating hub and tighten the fixing screws evenly. Verify the actual M 4 radial and axial thread positions against the dimensioned view. Use an appropriately sized mating fastener with adequate engagement; an axial wheel bolt is not listed as included.
This is a rigid adapter and does not compensate for shaft misalignment. Support external loads and check screw security before operation. Do not assume a torque, speed or precision rating that has not been specified.
Applications
Small robot wheel drives, DC gear-motor prototypes and compact mechanisms requiring a matching 12 mm hex connection with a selected shaft bore.
What's Included
One selected brass coupling, two fixing set screws and one hex key. Product photos showing multiple sizes illustrate alternatives and viewing angles, not a multi-coupling pack. Motor, wheel, gearbox and mounting assembly are not included.
FAQ
Is a 2 mm bore available in the 30 mm length?
No.The 2 mm bore is offered only in the 18 mm length; the extended version starts at 3 mm.
Is this a flexible shaft-to-shaft coupling?
No.It is a rigid hex adapter with a selected shaft bore and threaded fixing references. Match the actual shaft and mating hub geometry.
Does the package include the motor and wheel?
No.It includes one coupling, two fixing set screws and one hex key.
Visual Details





