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Chapter 11: Input of Dimensions

By Peter Smid
From CNC Programming Handbook: A Comprehensive Guide to Practical CNC Programming, Second Edition

OVERVIEW

Addresses in a CNC program that relate to the tool position at a given moment are called the coordinate words. Coordinate words always take a dimensional value, using the currently selected units, English or metric. Typical coordinate words are X, Y, Z, I, J, K, R, etc. They are the basis of all dimensions in CNC programs. Tens, hundreds, even thousands of values may have to be calculated to make the program do what it is intended to do - to accurately machine a complete part.

The dimensions in a program assume two attributes:

  • Dimensional units

English or Metric

  • Dimensional references

Absoluter or Incremental

The units of dimensions in a program can be of two kinds - metric or English. The reference of dimensions can be either absolute or incremental.

Fractional values, for example 1/8, are not allowed in a CNC program. In the metric format, millimeters and meters are used as units, in the English format it is inches and feet that are used as units. Regardless of the format selected, the number of decimal places can be controlled, the suppression of leading and trailing zeros can be set and the decimal point can be programed or omitted, as applicable to a particular CNC system.

ENGLISH AND METRIC UNITS

Drawing dimensions can be used in the program in either English or metric units. This handbook uses the combined examples of both the English...

Copyright Industrial Press 2003 under license agreement with Books24x7
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