< Tender Wheels >
To begin with, the wheels are prepared. Before cutting, the wheel castings are annealed in the electric furnace so as to remove 'chill'. Heat up to 850 centigrade and cool slowly in the furnace. The furnace is so small that it needed five times operations.
The cutting process is the same as the leading and pony trucks of the engine. But their tire's profile is reinforced by increasing angle of the flange.
Centering roughly in the four-jaw, turn the back face, finish the center hole and cut recess around the spokes. I utilized four-jaw because my three-jaw is too small to chuck the wheel.
This is a trick so as to turn off the lathe power in desired position. Don't rely on such a trick too much for your safety.
The photo shows a wheel fixture in the lathe which was employed not only for the leading and pony truck wheels but also for William and Hunslet driving wheels, except the center spigot that is replaced every time and trued up before utilizing the fixture. Also the rim surface of the fixture is trued up every time. The two screws at the middle of the fixture are against the wheels rotating in the fixture.
The top side that is boss and rim is turned in the fixture.
Cut small steps by inching a knife tool in 0.4 mm step according to calculated coordinates. The photo shows cutting round edge of the back face. Finally the micro notches are removed by smooth files applied at the lathe top speed.
I turned nine wheels including one spare and there is no blowhole.
The axle is turned from 20 mm dia. silver steel rod. First, each end is squared and center drilled. The axle blank is too thick to pass through the lathe head, so the far end of the rod is supported by the fixed steady.
The steps for fitting wheels are turned in both center setting. This time, the other steps for fitting roller bearings are not cut, because the roller bearings will be pressed into the axleboxes and the bearing's inner radius will change due to the press fit condition.
The wheels are temporary fitted into the axles. They will be glued after painting and inserting eccentrics for the axle driven pumps.
