Acu-Rite CNC 3500i user manual Setting the datum, Fixture Offsets

2.1 Fundamentals of Positioning

Setting the datum

Fixture Offsets

A production drawing identifies a certain form element of the work piece, usually a corner, as the absolute zero datum. When setting the datum, you first align the work piece along the machine axes, and then move the tool in each axis to a defined position relative to the work piece. Set the display of the CNC either to zero or to a known position value for each position. This establishes the reference system for the work piece, which will be used for the CNC display and your part program.

If the production drawing is not dimensioned for that particular CNC, set the datum at a position or corner on the work piece which is suitable for deducing the dimensions of the remaining work piece positions.

The fastest, easiest and most accurate way of setting the datum is by using a 3-D touch probe from HEIDENHAIN Corp. Refer to chapter "7.3 Probing Cycles on page 197”.

Example 1: Offset

See "Fixture Offset (Work Coordinate System Select):" on page 136 for more information on using the Offset cycle. Use the Offset command to apply a Fixture Offset of the absolute zero datum to the corner of WorkPiece #1.

Format: Offset Fixture #1 X10 Y10

Offset Fixture #1

Machining positions are now referenced from the lower left corner of WorkPiece #1.

Use the Offset command to apply a Fixture Offset of the absolute zero datum to the corner of WorkPiece #2.

Format: Offset Fixture #2 X60 Y10

Offset Fixture #2

Machining positions are now referenced from the lower left corner of WorkPiece #2.

32 2 Machining Fundamentals