LOCOMOTIVE

 

Building the engine shown below is essentially a matter of preparing all the parts illustrated on page 23 and gluing them to the chassis. You can cut and assemble or cut all the pieces first, then glue only when all the components are ready. To help you produce a scale model, the profile and dimensions of all the necessary parts are provided. The following pages show step-by-step instructions for producing the more challenging pieces. Although the locomotive is made mainly from wood, a few items of met­al hardware are required. You will need %-inch-long No. 16 brass escutcheon pins, for example, to attach the con­necting rods to the wheels. Drill pilot holes for the pins Vt inch from the cen­ter of the wheels. The connecting and drive rods are cut from 2‘X-inch-long 0.025-gauge ^-inch-wide brass strips. The spacing between the holes through each end of the connecting rods should

 

be equal to the distance between the dri­ve wheels: 2-At inches. Make the piston from a 2!4-inch-long, %:-inch-diameter brass rod with a hook at one end and

 

attach it to the drive rod. Push the piston into a 1 % length of ^-inch-diameter tub­ing, then fit the tubing into the cylinder glued to the chassis.

 

Fire wall (N)

 

Headlamp (33)

 

Connecting rod (Q)

 

Piston (5) Condenser (Y) Cylinder (Z) Drive rod (R)

 

Smoke stack (C)

 

Smoke box hatch (E)

 

Catwalk (H)

 

Smoke box braces (P)

 

Interface strip (F)

 

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Pilot (G)

 

Зоііег (І)

 

Coupler (0)

 

Truck axle Truck axle washer (X) peg (W)

 

Drive wheels (T) Chassis (P)

 

Paired with the shop-made jig shown on page 25, a drill press bores a spoke hole through one of the locomotive’s wheels. Consisting of two rings that sandwich the wheel, the jig ensures that the wheels will end up identical. The jig’s outer ring features 12 brass bushings spaced equally around its circumfer­ence. As a result, the spoke holes will be equidistant around the wheels. After drilling the first hole, insert a dowel or brass rod through the jig rings and the wheel to keep the pieces from rotating as you bore the remaining holes. See detailed instrutions on page 25 for making this jig.

MAKING THE WHEELS

the flanges are the same width all around the wheel. Follow the same procedure for the front wheels, using li^- and 1-inch hole saws. Once all the cuts are made, release the wheels from each blank using a belt sander fitted with an 80-grit sanding belt. Turn over the blank and secure it to the top of your bench. Move the sander back and forth across the surface until it removes enough waste wood to expose the hole saw cuts (above, right). You can now cut imitation spokes into the drive wheels (step 2) or use a jig (page 25) to construct more detailed drive wheels with spokes made from dowels.

Cutting “spokes” into the drive wheels

To create the illusion that the drive wheels are spoked, you can use a backsaw to kerf the outside faces of the wheels. To hold the wheels as you cut them and ensure that the kerfs are spaced equally, use a jig made from a board slightly thicker than the wheels. For the jig, cut a 2^-inch hole into the middle of the board and mark the kerf lines around the circumference of the hole. Spacing the marks 30° apart will allow you to cut 6 kerfs. Secure the jig to your benchtop, insert the wheel in the hole, and transfer the kerf marks onto it. Then holding the wheel in place with an index finger, cut a kerf into the jig and /ь inch into the wheel (left). Keep the saw teeth parallel to the work surface. To cut each remaining kerf, rotate the wheel in the jig until the next kerf mark aligns with the cut in the jig and repeat the cut.

A SPOKE-HOLE JIG

The jig shown at right will enable you to make quick work of drilling equidistant holes for spokes around the rim of drive wheels like the ones shown in the photo on page 20. The jig consists of two rings: an outer and inner one. The wheel and hub are held steady for drilling by the two rings; the flange along the wheel’s circumfer­ence prevents it from slipping out.

Cut the two rings from a board the same thickness as the wheels. Use a З-inch hole saw to define the outside circumference of the outer ring and a 2-inch hole saw to separate the two rings. Use a ^-inch-diameter bit to drill out the hole in the inner ring for the hub; use a short length of dowel for the hub. To prepare the jig, assemble the rings and the hub, and use a %z-inch drill bit to bore holes at 30° intervals through both rings. After drilling the first hole, slip a 1^-inch dowel into it to keep the rings aligned as you bore the remaining holes. Once all the holes are drilled, insert a piece of brass tubing in each hole in the outer ring, sized to accept a i^-inch drill bit. Refer to the color photo on page 24 for instruc­tions on using the jig.

MAKING THE BASE ASSEMBLY

1

Shaping the chassis and the pilot

Refer to the anatomy illustration on page 22 for the dimen­sions of the locomotive chassis. Cut it to shape on your band saw and remove any marks left by the blade with a sanding block. Make the pilot from a y4-by-2’/4-inch hardwood board, long enough to feed safely across your table saw. To cut the grooves in the pilot, adjust the blade height to Ae inch and position the rip fence for a cutting width equal to the width of
the blade kerf. Feed the board across the table to cut the first groove, them shift the fence away from the blade by twice the kerf width and repeat. Cut the remaining grooves the same way, feeding the stock with a push stick and pressing the board against the fence at the trailing edge of the stock with your free hand (above). Once all the grooves are cut, saw the pilot to shape on a band saw (below).

2 Preparing the chassis for the wheels

Clamp a backup panel to your drill press table and install a ^-inch bit to bore the axle holes for the drive wheels. Mark the holes 1 inch and 31^ inches from the back end of the chassis. Then, holding the chassis on its side, drill each hole through the stock (left). Bore matching holes through the wheel hubs or centers.

3

Making the truck axle assembly

Refer to the anatomy illustration (page 22) for the shape of the truck axle, then cut out the shape on your scroll saw (above). Drill the axle holes in the assembly and front wheels using a )ffi-inch bit. Install the wheels with ‘^-inch-diameter pegs.

4

Attaching the wheels to the chassis

To mount the front wheels, drill a ‘%t – inch-diameter hole into the underside of the chassis near the front end and install the truck assembly with a ‘A>-inch peg (left). Also attach the drive wheels to the chassis using ^-inch-diameter pegs.

MAKING THE CAB

1 Cutting the windows

The locomotive cab consists of six parts: two side walls, shown at left, a firewall and base (below), the cab jack, and the roof (step 3). Refer to the anato­my illustration on page 22 for the dimen­sions and shapes of these pieces. Cut them all to size on your scroll saw. When sawing the window notches in the side walls, keep the stock from jumping off the saw table with a hold-down (left).

4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

3 Shaping the roof Make the roof of the cab from a %-by – 2/4-by-2%-inch piece of hardwood. Mark the slope of the roof on the long edge of the stock, then use a disk sander to round over the surface. Holding the edge of the stock flat on the sanding table, rock the top of the roof back and forth across the abrasive disk until you cut to the marked line (right). Once you are satis­fied with the shape of the roof, glue it to the rest of the cab and mount the cab to the chassis on top of the cab jack.

MAKING THE BOILER AND DOMES

1 Turning the boiler and smoke box You can turn the boiler and the 114- inch-long smoke box separately, using contrasting woods. But if you wish to make them from a single workpiece, mount a 7v4-inch-long blank between centers on your lathe; white ash is a good choice for these parts of the pro­ject. Make the blank h inch longer if you also want to produce the smoke box hatch from the same blank. Turn the workpiece into a cylinder with a roughing gouge, then use a piece of wire to burn a demarcation line between the boiler and smoke box (photo, page 21). To turn the smoke box hatch down to a diameter of 1 inch and its top down to V< inch, use a skew chisel (left). If you are making the hatch separately, use ‘i-inch dowel stock cut from a contrasting hardwood.

Boiler and smoke box blank

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Skew chisel

2 Preparing the boiler and smoke box for the stack and domes

Once you have turned the boiler and smoke box, bore the holes for the smoke stack, the steam dome, and sand box on your drill press. Cut a V-shaped wedge out of a wood block, creating a jig that will hold the workpiece steady as you drill the holes. You need to bore three holes with three different bits: one % inch in diameter, located l A inch from the back end of the boiler; a second 1 inch in diameter, 2 inches away from the first hole; and a third inch in diameter, located Ул inch from the front end of the smoke box. Hold the workpiece securely in the jig as you drill each hole (left).

3

Making the domes

Shape the domes for the smoke stack, steam dome, and sand box from dowel stock of the correct width. Install a piloted round-over bit in a router and mount the tool in a table. To help you keep the dowel square to the cutter, clamp a pair of guide blocks and a hold­down to the table, as shown at right. Cut a notch out of one end of the hold-down and place it on a shim so the notch will be just above the workpiece and prevent it from jumping up when it contacts the bit. Standing on the right-hand side of the table and holding the dowel against the narrow guide block, advance the workpiece toward the bit. When the dowel contacts the pilot, press it against the block and rotate it toward yourself to shape the end. To finish the dome, simply cut it to length. You can also saw off the dome and glue it to a dowel made from a contrasting hardwood. Once all the domes are made, glue them to the boiler and smoke box.