Appx B - Alternate Tool Setting Methods

Upon successful completion of this lesson, you will be able to:

Contents

Overview

One of the most confusing things about CNC's is how to set tool length offsets and how they relate to machine fixture offsets. Chapters 4 (Coordinate System) and 6 (CNC Operation) detailed one method of using Tool and Length offsets. While this is one of the most flexible and useful methods it is not easy for beginners to understand and has other disadvantages.

This chapter shows three other methods of setting tool lengths. To summarize, here is a table that lists all four methods described in this course:

Method

Description

Advantages

Disadvantages

1

Use scrap of notebook paper.

  • Easy to understand.
  • Easy to use.
  • Does not require using Fixture Offset Z.
  • Safe.
  • Not as accurate as other methods.
  • Requires part to be manually face milled before setting tools.

2

Use 1-2-3 Block on finished face of part.

  • Very accurate.
  • Easier to understand than method requiring use of dial indicator.
  • Not as safe as paper or tool probe method.
  • Requires part to be face milled before using.
  • Requires also setting Fixture Offset Z.
  • If Z-datum is milled away, tools cannot be reset easily.

3

Use 1-2-3 Block and dial indicator (Method described in Chapters 4 and 6).

  • Very accurate.
  • If Z-datum is milled away, tools can be reset easily in case of broken or worn tool.
  • Can be difficult to understand for beginners.
  • Not as safe as paper or tool probe method.
  • Requires also setting Fixture Offset Z.

4

Use tool probe.

  • Easy to use.
  • Very fast.
  • Accurate.
  • Easy to understand.
  • Requires machine equipped with tool probe.