Indexing

Lathe Operations
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Step 2. Using a micrometer, measure across all three set screws (figure 35

on the following page). Total the 3 readings and divide them by 3.

Step 3. Loosen the top set screw and adjust the other two set screws to the

dimension outlined in step 2.

Lock these two set screws with jamnuts.

Tighten the top set screw against the workpiece. Recheck all three settings

Example: Using .751 diameter stock and with readings of 3.058, 3.085, and

3.071 totaling 9.214, and divide this reading by 3. The reading should be

3.071. The three set screws should be adjusted to the 3.071 dimension.

(b) When machining a quantity of like parts having exactly the same

diameter, two of the set screws can be kept securely tightened with the jam

nuts after centering the graduated collar for the first machined part.

After machining, the graduated collar is removed by loosening the screw

which does not have a locknut. The collar can then be used for machining

the remaining parts without having to measure the concentricity each time.

(6) Internal Keyway Cutting. Internal keyways are cut with the same type

of set-up as used for boring. The fixture is mounted on the lathe compound,

with the fixture plate parallel to the lathe bed. Mount the boring bar in

the V-groove keeping the tool slot of the boring bar in a vertical position,

so that the cutter may be brought up to the top position of the workpiece

bore. Use the lathe cross-slide to center the