David Elliott and Mick Robinson had a successful weekend at Darlington Locomotive Works. The main frames now have the bends in them, and the remaining frame plates have been set up and temporarily bolted to the main frames.  The bends in the rear frames (needed to allow room for the Cartazzi wheelset to move sideways without the wheels hitting the frames) were achieved as follows:

A bending former was made up using a piece of steel plate normally used to the protect the inspectionpit boards from exceptionally heavy loads, to which was temporarily welded a hefty piece of rolled steel joist (RSJ) which forms part of the boiler cradle, a specially pressed former to provide the correct bend diameter and a spare piece of angle to brace the upright to the floor plate.  This was carefully lined up with the inside of the required bend and secured to the rails by large tack welds.

07121402First frame bending setupDE

The rig is set up around the frames to start the bending process – David Elliott

07121403Frame bending formerDE

The former around which the bending will take place – David Elliott

The area of the frame to be bent was then heated using two large oxy-propane torches, two being required to reach the necessary dull red heat in the whole of the width of the 30mm plate being bent. Two complete bottles of oxygen were used, made possible by the loan of a second oxy-propane set from M Machine.  The rear end of the frame was then formed into the correct place using the fork truck, the angle of the bend being checked with a laser profiled template CNC cut from the 3D model of the frames.

07121404First bend successfulDE

The first bend successfully completed – David Elliott

07121405Set up for second bendDE

The rig re-set for the second bend – David Elliott

Once the team were happy with the initial bend, the whole rig was reorganised with the bending former outside the frames to make the rear bend which returns the back of the frame parallel to the main part of the frame.  This time there was no room to use the fork truck between the frames, so an alternative method was employed using the ten tonne jack set to push the end of frame being bent.  Once all four bends were in place, the doublers under the front of the firebox and the rear outer (Cartazzi) frames were temporarily bolted on. For now the frames are held together (and apart) by threaded rod and tubes cut to the required distance between the frames.

07121406LH frame bends completeDE

The completed bends – David Elliott

07131401Mick warms up the third bendDE

Mick Robinson warms up the next area to be bent – David Elliott

07131403Mick studies his handyworkDE

With the inner frames bent to shape, the Cartazzi frames could be bolted on – David Elliott

07131405Detail of frame joints at front of fireboxDE

One of the frame joins and the threaded bolts securing the plates together – David Elliott