< Bending Rolls >
Before starting the platework, I decided to prepare a home made 'bending rolls' which will be used to bend the cab roof. It is a typical three rolls type. I designed it as simple as possible. The effective length is 375mm and the diameter of rolls is 30mm.
To prepare the pedestals, I gathered three of narrow BMS bars into a piece by silver soldering. A brass stud and nuts were used to fix the bars together, during soldering operation. After that, the stud was cut out and filed flush.
Slit in the pedestal, in which the axlebox will slide up and down, should be truly parallel. It was trued up by 16mm dia. endmill.
Finished pedestals. The three holes were drilled and reamed. The top bar is a stay for push-bolt of the axlebox.
Assembled frames. The base plate has a pair of narrow steel bars at its bottom, which will be chucked in a vise, in practice. All of components were assembled with 6mm dia. steel bolts.
I obtained suitable gears from a gear supplier. It was made of silver steel and hardened. Note they have bushes for set screws.
The rolls are made from a length of 30mm dia. silver steel. Great labor with a hacksaw !
The rolls are too fat to go through the lathe headstock, So I employed 'fixed steady' to turn the rolls at right end of the lathe bed. The roll length is limited by the lathe bed length. Incidentally, turning with 'fixed steady' can achieve more accurate result than that with 'three-jaw'.
End of the bar was slightly flattened, so as to secure the gear with a set screw.
Finished rolls. The thinner one is a driving shaft of the gear set.
The axlebox was made from a gunmetal round bar. It was cut, faced, drilled, reamed in the lathe, then squared by milling. Instead of flanging, I employ a snap ring to hold the axlebox in the rolls. Note a short piece of steel is glued onto the axlebox, which will protect the gunmetal axlebox from the steel push-bolt.
The rolls and gears were assembled, then insert a steel bush into end of the driving shaft, which hold the operating handle. Now the machine was completed.