Taper shaft machining

Client: Melita Marine Group 

Project: In-Situ Repair of Propeller Shaft Taper Journal 

Royce Onsite Machining was contracted by Melita Marine Group to carry out a precision in-situ repair on a historic vessel, following a propeller failure. The incident caused significant damage to the taper journal on the propeller shaft — a critical interface requiring accurate restoration to avoid the need for full shaft replacement.  

Project Scope 

To restore the shaft, our team deployed custom-built orbital machining equipment, developed in-house for this specific application. Using specialised tooling, we accurately machined the damaged taper journal in-situ, removing only the minimum material necessary to preserve the shaft’s structural integrity. 

Key aspects of the operation included: 

• Establishing accurate machining datums on a worn shaft surface 
• Machining and polishing across an existing keyway 
• Maintaining tight tolerances while limiting material removal 
• Preserving the centreline of the taper shaft  

Technical Specifications 

• Shaft Diameter: 180 mm 
• Taper Angle: 2.37° 
• Machining Tolerance: Within 0.02 mm 
• Flatness Achieved: 99% 
• Surface Finish: 0.3 Ra  

Outcome 

With the vessel in dry dock and a strict deadline in place, our technician completed the in-situ repair within three days of arrival. 

• The propeller was replaced, while the original shaft was successfully retained and returned to service 
• The client avoided costly delays and the expense of manufacturing a new shaft 
• The repair met all dimensional and performance requirements