49's Crown Stays

49's boiler is under repair at Israel Newton's boiler workshop in Matlock.

The photos below are courtesy of John Eastwood of Newton's, via Richard Charlton.

Firebox crown stays ready to be installed in 49's boiler
Note the threads of the ends must enter both inner & outer plates in sync,
hence the need for a long tap to cut threads in both plates at the same time

Inside the firebox, which is on its side,
a few crown stays waiting for nuts protrude through the crown sheet

Outside, the curve of the plate above the firebox means that crown stays are
of different lengths, and some enter the plate on a curve & at quite an angle.

The photos above are courtesy of John Eastwood of Newton's, via Richard Charlton.

Crown stays are the vertical stay bolts shown in this cutaway