The new cylinder blocks have been redesigned and manufactured to bring the width and height within the current Network Rail Loading Gauge – essential for future mainline running and similar to the design adopted for 6024 - King Edward I.
Bob Meanley also produced an assembly drawing to show how best to fit the donor 41xx pony truck to 4709. This last drawing was essential to support the work on the pony truck by Leaky Finders in Exeter and ensures that all the many critically important interface details have been addressed.
Timber patterns for the new cylinder covers, as well as the two huge Compensating Beams have now been ordered.
After more than a few trials and tribulations, the first of the two new cylinders for 4709 have now been cast. Preparations are well advanced to cast the second cylinder shortly.
4709’s Chief Engineer, Paul Carpenter explains; “Premier Patterns in Smethwick produced the polystyrene patterns, which were completed and inspected during February 2020, then dispatched to the Shakespeare foundry in Preston for casting. It had successfully cast locomotive cylinders using poly patterns for several other projects, but luck wasn’t with us - on the day our patterns arrived at the foundry, the company was placed into receivership.”
“We were fortunate to be able to extricate the patterns from the receiver and a search was started for another foundry. We quickly discovered that in our modern manufacturing world, the number of suitable candidates is significantly less than a century ago, when 47xx cylinders were first being cast.
We contacted every foundry currently producing cast iron products, only to discover little enthusiasm for the project. Either the sheer size and volume of the casting or concerns centered around the specialist knowledge required to work with poly patterns, caused most to decline to bid for the contract. Months were spent in detailed discussions with one foundry, only to have them decide at the last moment that they too could not deliver the castings” adds Paul.
Background enquiries identified one specialist; a man who had worked successfully with polystyrene patterns to produce locomotive cylinders. From the first discussion with Alan Boulton, it was obvious that he was a man with both the specialist knowledge and a genuine enthusiasm to deliver this work – he clearly possessed the ‘can do mentality’ required and on his recommendation, Boro Foundry were contracted to deliver our castings.
This foundry has often undertaken work for our parent Great Western Society and are currently machining the coupling rods for the County 1014 Project. With a full team and the necessary skills and experience on board, Boro Foundry’s Sam Edwards, Alan and the 4709 engineers started on the research and development work necessary to ensure the casting process would succeed. Working as a single unit, the team re-engineered the casting process for steam cylinders with poly patterns from first principles.
The casting team outside Boro Foundry. From L to R: Kevin Shakespeare – Finish fettler, Andy Hinsull – Moulder, Mike Solloway - 4709, Craig Rollinson – Foundry Manager/Moulder, John Rollinson – Foundry Managers Assistant/Moulder, Sam Edwards – Operations Manager/Sales