Centroid Community CNC Support Forum

Just though I'd post this here as a reference for the DIY'ers when setting up their machine tool coordinate systems. All illustrations were taken from ISO 841:2001(E) Industrial automation systems and integration — Numerical control of machines — Coordinate system and motion nomenclature
Z-Axis
The Z axis is parallel to the principal spindle of the machine.

• On machines used for milling, grinding, boring, drilling and tapping, the spindle rotates the tool.
• On machines such as lathes, cylindrical grinders and others which generate a surface of revolution, the spindle
  rotates the work piece.
• For cutting and forming machines, the Z axis shall be perpendicular to the work-holding surface.
• For coordinate measuring machines, the Z axis should be collinear with the acceleration of gravity vector (i.e.
  perpendicular to the surface of the earth).

X axis
Where possible, the X axis shall be horizontal.

• Machines with rotating tools
  • Horizontal Z axis: Positive X shall be to the right when viewed in the negative Z direction.
  • Vertical Z axis, single column: Positive X shall be to the right when viewed from the front of the machine into the
    column.
  • Vertical Z axis, gantry type: Positive X shall be to the right when viewed from the principal spindle to the left-hand
    gantry support.
• Machines with rotating workpieces
  • The X axis shall be radial and parallel to the cross slide. The positive direction shall be away from the axis of
    rotation.
• Machines with no spindle
  • For cutting machines, positive X shall be parallel to and in the principal direction of cutting.
  • For coordinate measuring machines, positive X shall be defined by the manufacturer.

Y Axis
Positive Y shall be in the direction to make a right-hand set of coordinates

Examples

thanks Tom!

here is a good link to go with this info.

https://www.autodesk.com/products/fusio ... made-easy/

As Marc pointed out in the copy of this thread in the All Others forum, Motion is relative to the "tool" and positive directions are in the direction the tool would move. On machines where the table moves, "negative" table movement (denoted by the ' on the axis designation) is "positive" cutter movement.

On a knee mill, positive X is the table moving to the left (cutter "moving" to the right), positive Y is table moving away from column (cutter "moving" towards the column).