34059 boiler and firebox
Credit: Bluebell Railway


Bluebell Resident Locos 34059 and 21C123 are having their new fireboxes built. Six new inner fireboxes are currently under construction at the engineering section of the South Devon Railway with help of the Firebox press

The boilers are being built from steel, Oliver Bulleid chose steel for the Pacific class fireboxes for a number of reasons. These were: copper was more expensive and was in short supply. Steel firebox repairs involving welding could be done at MPDs.


The decision to replace the inner fireboxes for a number of Light Pacifics gave the SDR the opportunity to start a production line.

Many of the components are being pressed using the 700-ton Shaw Press. This was previously owned by Pridhams, but was taken over by the South Devon Railway.

South Devon Railway Engineering has suggested that it might be possible to revert to the southern practice. They could produce the combustion chamber and throat plate as a single pressing. The Shaw has shown the SDRE is capable of a massive job like this.

The initial 3D printing of the male and female dies has been created.

When producing a pressing, the steel plate is heated to 800 degrees, placed between the dies in the press and the result in 4 minutes is a combustion chamber and a throat plate which is pressed.

Update on 34059 and 21C123

34059s inner firebox is the first in the production line. This is now in the final welding stage before marking out for the stays is completed. The inner firebox will be inserted into the outer wrapper and then the foundation channel will be welded to the outer wrapper. The drilling and reaming of the 2000 stays will be completed at the Bluebell Railway.

Bulleid No. 21C123 has had its components for the new inner firebox pressed to enable work to start.




  1. Would be nice to see a mn built as the original 21c1 channel packet with the original narrow cab , I know visibility was an issue but looks great !


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