Boiler Design III
The drawing above shows some of the holes that must be drilled in the smoke box.
The 2" diameter hole in the top is for the smokestack. Additional holes are required to secure the smokestack to the smoke box. The smokestack can be used as a template for those holes.
The 13/16" holes are for the steam supply lines to the cylinders. Four additional holes are required to attach the steam supply plates over these holes. The steam supply plates can be used as templates for these holes.
The 1.25" hole in the bottom is for the exhaust nozzle to pass through to the saddle. Additional holes are required to pass the screws securing the exhaust flange the saddle.
Smokestack: The MRSR91 smokestack is shown in the photo above left. I decided to use a casting from Allen Models, part number M211/1. The casing is aluminum and easily finished with a file and Emory paper on the lathe and on the belt sander. The approximate finished dimensions are shown in drawing above right.
Fire Box Door: The MRSR91 fire box door is shown in the four photos above. The door incorporates a draft vent with a damper controlled by the small lever on the left side. The draft air enters from the bottom. I assume that the plate with holes facing the fire box is a grate to minimize flame bursts from going through the door.
The fire box door base squares up the surface around the weld fillet.
This drawing shows how a suitable door can be made using a piece of square tube and a piece of round tube.
A damper plate must be cut to fit inside the square tube and handles for the latch and damper must be designed. These designs were done after the rest of the door was fabricated. See the Boiler Constriction I page for more details of the fabricated door.