tandards.

Make a bold scratch across the bedplate to show where the centre line of
the shaft should be, and another along the bed for the piston-rod centre
line. (Position given on p. 138.)

Bore holes in the bearings for the oil cups, which may be merely forced in
after the engine is complete.

The crank boss may be made out of a brass disc 2-3/4 inches diameter and
3/16 inch thick, from which two curved pieces are cut to reduce the crank
to the shape shown in Fig. 53. The heavier portion, on the side of the
shaft away from the crank pin, helps to counterbalance the weight of the
connecting and piston rods. In Fig. 54 (plan of engine) you will see that
extra weight in this part has been obtained by fixing a piece of suitably
curved metal to the back of the boss.

The mounting of the crank boss on the shaft and the insertion of the crank
pin into the boss might well be entrusted to an expert mechanic, as
absolute "squareness" is essential for satisfactory working. Screw-thread
attachments should be used, and the crankshaft should project
sufficiently to allow room for a flat lock nut. The crank pin will be
rendered immovable by a small lock screw penetrating the boss edgeways and
engaging with a nick in the pin.

Fixing the Standards and Bearings.--Place the two bearings in their
standards and slip the crank shaft through them. Place standards on the
bed, with their centre lines on the crank-shaft centre line. The face of
the crank should be about 3/8 inch away from the piston rod centre line.
Bring the nearer bearing up against the back of the disc, and arrange the
standards equidistantly from the ends of the bearing. The other bearing
should overlap the edge of the bed by about 1/8 inch. Get all standards
square to the edge of the bed, and mark off the positions of screw holes in
bed. Remove the standards, drill and tap the bed-plate holes, and replace
parts as before, taking care that the lubricating holes in the bearings
point vertically upwards. Then solder bearings to standards.

If any difficulty is experienced in getting all four standards to bed
properly, make the bearing holes in the two inner ones a rather easy fit.
The presence of the crank-shaft will assure the bearings being in line when
the soldering is completed.

The standards and bed should have matching marks made on them.

The Eccentric.--This can be formed by soldering two thin brass discs
1-15/16-inch diameter concentrically to the sides o