A thumbnail switcher
The white metal radiator casting (left) and etched brass louvered doors have been glued in place on the hood casting. Next, the superstructure (right) is airbrushed with Floquil Primer. After it
side in place with a strip of .010″ styrene insulating it from the floor us- ing the screw holes as a temporary guide and clamp while the glue set. Be- fore doing so, I soldered a .010″ phos- phor wire wiper to the frame in a posi- tion to contact the drive wheel. I mounted the motor, leaving the mounting screws loose, then attached the hot frame, sandwiching the wheel- sets in place and making sure they could turn freely before tightening the screws holding the frames to the foot- plate. I then adjusted the mesh of the worm and the molded gear on the axle until the assembly ran smoothly on test leads, and then tightened the screws holding the motor. With the chassis as- sembled, I shifted my attention to the superstructure.
The cab includes one etching for the sides and front, including the light mounting brackets which protrude through the roof. There’s an etching for
is dry, the superstructure is airbrushed again with Floquil Yellow. The chassis is easier to paint with a brush. Note the holes that are drilled in the cab roof and hood for the brass exhaust pipe.
the roof and four etchings for the win- dow sash, to be applied to the inside of the cab. The joint in the cab walls oc- curs in the center of one of the ends and is backed by one of the sash etchings. Corrugations on the bottom of the roof etching are intended to make the bending easier but actually telegraph through to the upper surface. After as- sembly of the cab, use a small, fine file to dress the top surface of the roof to hide these corrugations.
Instead of using the white metal castings for the headlights, I built op- erating headlights using surface mount warm gold LED’s from Richmond Con- trols. These come with a dropping re- sistor to allow them to be used with the output of a DCC decoder. I drilled out a .070″ diameter styrene rod and fitted the LED into the rod, securing it with cyanoacrylate. Next, I stripped the in- sulation from a grain-of-wheat lamp and used this to insulate the copper
leads on the LED from the etched head- light bracket. Route the wires through a hole in the roof and leave them ex- posed to simulate electrical conduit. The superstructure is secured to the chassis with the coupler mounting screws. For the female threaded at- tachment, brass etchings are provided which are to be threaded, then glued into a recess in the bottom of the white metal hood castings. To assure align- ment of these pieces, I first attached the hoods to the chassis using the cou- pler mounting screws with the cab sandwiched between and tightly held down to the footplate. With everything in place, I carefully applied drops of cyanoacrylate to the joint between the hood castings and the cab wall, taking care not to get any between the foot- plate and the hoods or bottom of the cab walls. When the glue set, I then re- moved the assembly and applied addi- tional cyanoacrylate through the holes
The cab glazing (left) was applied from the inside. The front and the back of the cab require two pieces of glazing because the etched sashed overlay only partially covers the wall. The muffler
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and exhaust pipe (right) were painted a mixture of Burnt Umber and Burnt Sienna before installing. This was touched up where required. The inset photo shows a fuel filler cap on the hood.
JANUARY 2012
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