< Firedoor >
C53 class locomotive employed a modern butterfly firedoor. I reproduced its appearance but omitted the compressed air operating. The firedoor is operated only by hand with a lever.
For the firedoor frame, I prepared a chemical wood pattern by Modela and asked to make a gunmetal casting. The dummy air cylinder is gathered to the frame to cut costs down.
Saw off the air cylinder part and machine the rest frame part. First, the back face is finished in four-jaw.
The frame has hook shapes at the left and the right bottom parts. They are cut by a wood rough cutter.
The doors are laser-cut parts. They consist of the top plates and the bottom frames. I employed an involute curve for the gear parts.
The top plates and the bottom frames are aligned with pins and silver soldered. After that, drill the vent holes and the axle holes.
File the top edge round, silver solder a stop pin, screw nuts down and complete the doors.
Screw down the pins on the frame and set the doors. To control the sensitive play of the gear, the positions for the pins should be accurate.
This is the lever to open and close the doors. The lever must not only rotate but also tilt, therefore the hole in the bush is cut to an oval shape.
The left photo shows the lever bracket to operate the door. It is tiny but has complicated shapes. Make the top and the bottom parts separately, and then silver soldered. The top part is bent from a flat pattern as the right photo shows.
Mount the dummy cylinder part and the firedoor assembly is completed. The doors are open and closed by the lever.
Rotate the lever to open the door, push the lever down, and then the lever is caught in the notch of the left arc wall. If you pull the lever, then the doors close by their weight.
The firedoor assembly is fixed on the boiler backhead with three screws. Each screw hole in the backhead is lined with a copper plate, and the holes are blind.
