Part 5 (2/2)

For larger work, place the chisel flat on the rest with the toe next to the stock and the back edge of the chisel parallel to the face to be surfaced.

The point of the chisel is then forced toward the center of the stock, using the straight back of the tool as a guide against the finished surface. Only a very thin cut should be taken at a time.

[Ill.u.s.tration: Fig. 16.]

Note:--While this operation may be termed a sc.r.a.ping cut, it will be found to be much easier on the tool than if the cutting edge were held flat against the work as in other sc.r.a.ping cuts.

The surface of the work should be tested for squareness by holding the edge of the chisel or a straight edge across the face.

LAYING OFF MEASUREMENTS

In laying off measurements on the face of the stock a pencil compa.s.s or dividers should be used. Set the compa.s.s or dividers to one-half the diameter of the circle wanted. While one point is held at the exact center of the stock, which is easily located while the stock is revolving, the other is brought in contact with the revolving stock until a circle of the correct diameter is marked.

[Ill.u.s.tration: Fig. 17.]

Should the center of the stock be cut away, rendering this method impossible, the following method may be used: Set the compa.s.s or dividers to the exact diameter wanted. Place one point in contact with the stock a little to one side of the required line on the part that is to be cut-away. Bring the other point to the stock and see if it touches the line first made. If not, move the first point until the two points track in the same line.

[Ill.u.s.tration: Fig. 18.]

The rest should be set at the exact center for measuring.

All measurements on the edge of the stock can be made with pencil and rule as in cylinder turning.

B-I--2-a. Shoulder Cuts

1. EXTERNAL SHOULDERS. FIG. 18. The surplus stock at each successive shoulder is roughed out with a 3/4” gouge, keeping well outside the finished measurements. The gouge for this work is held in the same position as described in B-I--1-a, Step 1, for Roughing Off Corners.

[Ill.u.s.tration: Fig. 19.]

2. For the finis.h.i.+ng cut a small skew chisel is used, and the process is the same as that used in squaring ends of stock. Both the vertical and horizontal shoulders can be handled easily by this method. Fig, 19.

3. INTERNAL SHOULDERS. For internal shoulder cutting the same methods may be used for roughing out and cutting the horizontal shoulders, but for the vertical or base shoulder it will be necessary to use the sc.r.a.ping process. (See ”Use of Sc.r.a.ping Tools.”)

B-I--3-a. Taper Cuts

Taper cutting will not be found hard as the gouge and skew chisel are used in the same manner as described in B-I--1-a, Steps 4 and 5. After the stock has been roughed away with the gouge to the approximate angle desired, a smoothing cut is taken with the skew. Care should be taken that the skew chisel is held at the exact angle of the taper desired.

B-I--4-a. V Cuts

V cutting will also be found easy as the tool process is exactly the same as that used in spindle turning. Exercise A-I--4-a. Fig. 20.

B-I--5-a. Concave Cuts

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