Smokebox Saddle Machining – Update on Steam Locomotive 4709


Group 4709 has released their latest update on the construction of the tenth member of the Great Western Railway (GWR) 4700 Class No.4709.

Smoke box saddle

Great progress is being made by Brierley Hill-based Roach Precision Engineering in machining the saddle and cylinder block of the smoke box.

Using their modern CNC machine, Roach’s team will mill with straight cuts back and forth to produce the curves needed to allow the smoke box to fit properly.

Extension frames

Examination of the extension frames showed that some welds, made many years ago, have flaws which are currently being corrected.

Once this work is completed, the extension frames will be delivered to Roach, where holes in the main cylinder block can be drilled and tapped. Although the holes can be drilled based on the drawings produced by Swindon Locomotives Works, the best plan is based on the holes for the cylinder block over those for the extension frames, ensuring that the two fit together perfectly.

At the end of this job, the cylinder blocks can be transported to Tyseley Locomotive Works, where the team can start building the front of No. 4907.

Pistons Valves

Four piston valve liners have been cast and are now being shipped to Roach where they can be machined to size. This now leaves the piston heads and valves as the last items for the casting cylinder assembly.

For more information or to support The 4709 Group in building No.4709, please visit their website here

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