Acu-Rite CNC 3500i User Manual

ACU-RITE 3500i

A reference system is required to define positions in a plane or in 
space. The position data are always referenced to a predetermined 
point and are described through coordinates.

The Cartesian coordinate system (a rectangular coordinate system) is 
based on the three coordinate axes X, Y and Z. The axes are mutually 
perpendicular and intersect at one point called the datum. A 
coordinate identifies the distance from the datum in one of these 
directions. A position in a plane is thus described through two 
coordinates, and a position in space through three coordinates.

Coordinates that are referenced to the datum are referred to as 
absolute coordinates. Relative coordinates are referenced to any other 
known position (reference point) you define within the coordinate 
system. Relative coordinate values are also referred to as incremental 
coordinate values.

When using a milling machine, you orient tool movements to the 
Cartesian coordinate system. The illustration at right shows how the 
Cartesian coordinate system describes the machine axes. The figure 
illustrates the right-hand rule for remembering the three axis 
directions: the middle finger points in the positive direction of the tool 
axis from the work piece toward the tool (the Z axis), the thumb points 
in the positive X direction, and the index finger in the positive Y 
direction.

The CNC 3500i can control 3 or 4 axes optionally. The 4th axis is 
designated by the letter “U”.  The “U” axis function depends on the 
builder.