06/05/2026
🚂 P2 Valve Gear Development Update: we’ve taken delivery of a full-size 3D-printed cambox for the P2!
The model has been developed from original 2D drawings by David Elliott (Engineering Director), refined by Alan Parkin (P2 Design Engineer), and brought to life with key camshaft components 3D printed and machined by volunteer Peter Scott.
This has allowed the engineering team to physically assemble and study the mechanism in detail—helping us:
• Visualise how the valve gear operates
• Check clearances and assembly requirements
• Validate the overall design concept
Using a printed polymer cambox at this stage is a major advantage. It avoids the cost and long lead times of castings while allowing early identification of any refinements needed. It also gives a clear, real-world demonstration of the scale and complexity of the system—and enables a trial fit within the monobloc.
Encouragingly, results so far give strong confidence that the concept is fundamentally sound.
🔧 What’s next?
We are now moving to:
• Finalise quotations for the first metal cambox
• Use the 3D model to clearly communicate requirements to suppliers
• Progress towards casting, machining, and assembly
The programme remains a three-stage plan:
1️⃣ Build and test the first cambox (casting expected this winter, work into 2027)
2️⃣ Refine the design and produce the second unit
3️⃣ Optimise performance once in service
Only after testing the metal cambox will final design sign-off be made.
🚂 Support the Project
This progress is made possible by supporters of No. 2007. Every donation directly funds the design, manufacture, and testing of these complex components.
👉 Donate here: a1steam.com/p2donation
Together, we’re building Britain’s most powerful steam locomotive.