Part 14 (1/2)

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CENTERING BLOCKS.--Next provide a 4” 4” piece (G), 40 inches long, through which bore a 3/4-inch hole (8), 2 inches from the upper end, and four bolt holes at right angles to the shaft hole (8). Then, with a saw split down this bearing, as shown at 9, to a point 4 inches from the end. Ten inches below the upper end prepare two cross gains (10), each an inch deep and four inches wide. In these gains are placed the top rails (A), so the bolt holes in the gains (10) will coincide with the bolt holes (11) in the piece A. Below the gains (10) this post has a journal block (12), intended to be in line with the journal block (7) of the piece F.

[Ill.u.s.tration: _Fig. 242. Tail Stock._]

Then make a block (H) 2” 4”, and 6 inches long. This also must have a shaft hole (B), and a saw kerf (14), similar to the arrangement on the upper end of the post (G); also bore four bolt holes, as shown. This block rests between the upper ends of the lugs (C).

Another block (I), 2” 4”, and 6 feet long, with four bolt holes, will be required for the tail end of the frame, to keep the rails (A) two inches apart at that end.

THE TAIL STOCK.--This part of the structure is made of the following described material:

Procure a scantling (J), planed, 4” 4”, 24 inches long, the upper end of which is to be provided with four bolt holes, and a centering hole (15). At the lower end of the piece is a slot (16) 8 inches long and 1-1/2 inches wide, and there are also two bolt holes bored transversely through the piece to receive bolts for reinforcing the end.

A pair of cheekpieces (K), 2” 4”, and each 12 inches long, are mitered at the ends, and each has four bolt holes by means of which the ends may be bolted to the upright (J).

Then a step wedge (L) is made of 1-3/8” 2” material, 10 inches long.

This has at least four steps (17), each step being 2 inches long. A wedge 1-3/8 inches thick, 10 inches long, and tapering from 2 inches to 1-3/8 inches, completes the tail-stock.

THE TOOL REST.--This is the most difficult part of the whole lathe, as it must be rigid, and so constructed that it has a revolvable motion as well as being capable of a movement to and from the material in the lathe.

Select a good 4” 4” scantling (M), 14 inches long, as shown in Fig.

243. Two inches from one end cut a cross gain (I), 1-1/2 inches deep and 1 inch wide, and round off the upper edge, as at 2.

Then prepare a piece (N), 1 inch thick, 8 inches wide, and 10 inches long. Round off the upper edge to form a nose, and midway between its ends cut a cross gain 4 inches wide and 1-1/2 inches deep. The lower margin may be cut away, at an angle on each side of the gain. All that is necessary now is to make a block (O), 8 inches long, rounded on one edge, and a wedge (P).

[Ill.u.s.tration: _Fig 243. Tool Rest._]

A leather belt or strap (Q), 1-1/2 inches wide, formed into a loop, as shown in the perspective view (R), serves as a means for holding the rest rigidly when the wedge is driven in.

MATERIALS.--Then procure the following bolts:

4-3/8” bolts, 10” long.

8-3/8” ” 6” ”

20-3/8” ” 5” ”

5-3/8” ” 9” ”

THE MANDREL.--A piece of steel tubing (S), No. 10 gage, 3/4 inch in diameter, 11-1/2 inches long, will be required for the mandrel. Get a blacksmith, if a machine shop is not convenient, to put a fixed center (1) in one end, and a removable centering member (2) in the other end.

On this mandrel place a collar (3), held by a set screw, and alongside of it a pair of pulleys, each 1-1/2 inches wide, one of them, being, say, 2 inches in diameter, and the other 3 inches. This mandrel is held in position by means of the posts of the frame which carry the split journal bearings. This form of bearing will make a durable lathe, free from chattering, as the bolts can be used for tightening the mandrel whenever they wear.

[Ill.u.s.tration: _Fig. 244. Mandrel._]

The center point (1) is designed to rest against a metal plate (4) bolted to the wooden post, as shown in the large drawing.

FLY-WHEEL.--It now remains only to provide a fly-wheel and treadle with the communicating belt. The fly-wheel may be of any convenient size, or it may be some discarded pulley or wheel. Suppose it is two feet in diameter; then, as your small pulley is 2 inches in diameter, each revolution of the large wheel makes twelve revolutions in the mandrel, and you can readily turn the wheel eighty times a minute. In that case your mandrel will revolve 960 revolutions per minute, which is ample speed for your purposes.