Use 5/64 or 3/32 inch brass plate for these. Two pieces of the dimensions shown in Fig. 56 are needed. Scratch a line exactly down the middle of each, and a cross line 1/2 inch from one end. The other end should be marked, cut, and filed to a semicircle. Drill three 3/16-inch holes in the turnover for the holding-down screws. The two standards should now be soldered temporarily together at the round ends and trued up to match each other exactly. Place them in the vice with the bending lines exactly level with the jaws, split the turnovers apart, and hammer them over at right angles to the main parts. Whether this has been done correctly may be tested by placing the standards on a flat surface. Take the standards apart, and scratch a cross line on each 1-5/8 inch from the lower surface of the foot on the side away from the foot. Make a punch mark where the line crosses the vertical line previously drawn, and with this as centre describe a circle of the diameter of the outside of the barrel. Cut out the inside and file carefully up to the circle, stopping when the barrel makes a tight fit.

On the inside of the hole file a nick 1/8 inch deep, as shown in Fig. 56. Remember that this nick must be on the left of one standard and on the right of the other, so that they shall pair off properly.

Standards and barrel must now be cleaned for soldering. Screw one standard down to a wood base; slip one end of the barrel into it; pass the other standard over the other end of the barrel, and adjust everything so that the barrel ends are flush with the, outer surfaces of the standard, and the nicks of the barrel in line with the standard nicks. Then screw the other standard to the base. Solder must be run well into the joints, as these will have to stand all the longitudinal working strain.

The next step is the fitting of the cylinder covers. If you can obtain two stout brass discs 2-1/8 inches in diameter, some trouble will be saved; otherwise you must cut them out of 3/32-inch plate. The centre of each should be marked, and four lines 45 degrees apart be scratched through it from side to side. A circle of 15/16-inch radius is now drawn to cut the lines, and punch marks are made at the eight points of intersection. Solder the covers lightly to the foot side of their standards, marked sides outwards, and drill 1/8-inch holes through cover and standard at the punch marks. Make matching marks on the edges. Unsolder the covers, enlarge the holes in them to take 5/32-inch screws; and tap the holes in the standards. This method will ensure the holes being in line, besides avoiding the trouble of marking off the standards separately.

Bore a 1/4-inch hole in the centre of one cover--be sure that it is the right one--for the piston rod.

You can now proceed to the making of the piston-rod gland (Fig. 54, G1). Fig. 57 shows how this is built up of pieces of tubing and brass lugs for the screws. If possible, get the tubular parts trued in a lathe.

Before the gland is soldered to the cover, the cover should be put in place, the piston rod attached to the piston, and the parts of the gland assembled. Push the piston rod through the cover until the piston is hard up against the back of the cover. Slip the gland over the rod, turn it so that the screws are parallel to the foot of the standard, and make the solder joint. This is the best way of getting the gland exactly concentric with the cylinder so that the piston rod shall move without undue friction. But you must be careful not to unsolder the cylinder from its standard or the parts of the gland. Blacken the piston rod in a candle flame to prevent solder adhering.

Steam Chest

The walls of the steam chest are best made in one piece out of 1/2-inch brass by cutting out to the dimension given in Fig. 58. A sharp fret saw will remove the inside rectangle. Get both inside and outside surfaces as square as possible in all directions, and rub down the two contact faces on emery cloth supported by an old looking-glass.

Two perfectly flat plates of 1/8-inch brass are cut to the size given in Fig. 59, or a little longer both ways, to allow for working down to the same area as the wall-piece. This operation should be carried out after soldering the three pieces together. File and rub the sides until no projections are visible. Then drill twelve 3/32-inch holes right through the three parts. After separating them, the holes in the walls and what will be the cover must be enlarged to an easy fit for 1/8-inch bolts, and the valve plate tapped.

Now drill 3/16-inch holes centrally through the ends of the walls for the valve rod. If the first hole is drilled accurately, the second hole should be made without removing the drill, as this will ensure the two holes being in line. If, however, luck is against you, enlarge the holes and get the rod into its correct position by screwing and soldering small drilled plates to the outside of the chest. Also drill and tap a hole for the lubricator. The attachment of the gland (Fig. 54, G2) is similar to that of the cylinder gland, and therefore need not be detailed.

Fig. 56. Cylinder standard before being bent.

The Valve Plate (Fig. 59). -- Three ports must be cut in this--a central one, 7/8 by 3/32 inch, for the exhaust; and two inlets, 7/8 by 3/32 inch, 1/8 inch away from the exhaust. These are easily opened out if a series of holes be drilled along their axes.