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  • Always try to have one point from which to measure. Do not machine this point off part way through the job. This would leave you with no way of measuring the next operation. Plan ahead.

  • Remember the basic machining rule that says: "If the tool chatters, reduce speed and increase feed."

  • It takes a long time to accumulate the knowledge, tools and fixtures required for many different types of milling operations. Do not become discouraged by starting with a job that is too complex or by using materials that are extremely difficult to machine.

FIGURE 2-- The three axes of movement on a vertical milling machine.

SECURING THE WORKPIECE

The first problem encountered will be holding the work and aligning it to the machine. It is important for reasons of safety and accuracy that the workpiece be solidly secured. This may be the most difficult task, since once the work is clamped in position, the method of doing the entire job has been established. Usually, a rectangular block can be easily held in a vise. Note that round stock may also be held in a "V" shaped vise slot. Mill vises are specially designed to pull the movable jaw down as they tighten on it.

Certain objects can be secured with a 4-jaw lathe chuck, which is in turn clamped to the machine. Some irregular shapes, such as steam engine castings, may present greater difficulties. Often they may be clamped directly to the table. Very small or irregular

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