Workpiece Setting Error
A part goes on the table a degree out of square. The program was written for a part that is straight, so every feature comes out rotated with it, and the further from the datum, the worse it gets.
G54.4 corrects the program to the part instead. The setting error is described once as a
shift and a rotation, and the control applies it to every move until it is cancelled.
Why this is not a work offset
Section titled “Why this is not a work offset”A work offset moves the origin. It is added once, and a part that is rotated is still rotated after it.
This correction is a rigid-body transform: the path is rotated and then shifted, at every point along every move. A straight cut across a part clamped at an angle comes out straight relative to the part, not to the table.
Selecting a set
Section titled “Selecting a set”The correction is not written into the program. The program names which set to use.
G54.4 P1 (apply setting-error set 1)G54.4 P0 (cancel, no correction)P1 to P7 select a set. P0 cancels.
An index outside that range does not stop the program. It reports a warning and runs with no correction at all, which means the part is cut as though it were clamped perfectly. Check the warning; do not assume a program that kept running was corrected.
What a set holds
Section titled “What a set holds”Each set is six numbers, held in the machine’s channel configuration:
| Value | Is | Unit |
|---|---|---|
dx, dy, dz | how far the part sits from where the program expects it | mm |
rx, ry, rz | the rotation, as a vector: its direction is the axis turned about, its length the angle | radians |
The rotation is applied first, about the origin, and the shift after it.
A set that is not configured is not selectable. Selecting it leaves the program running uncorrected, exactly as a bad index does.
What it does not do
Section titled “What it does not do”- It does not measure the error for you. The six numbers are configured on the machine. Nothing on the panel writes a set from a probing cycle.
- It does not correct the machine. Squareness, droop and rotary centres are the machine’s own geometry. See Volumetric Compensation. This corrects one part.
- It does not fix a bent part, and it does not make up for a part that is not held properly. A clamp that lets the part move gives a different error every time, and no single set describes it.
- It is a licensed option. Without it, a block selecting a set is refused before the program runs.
Where to go next
Section titled “Where to go next”- Setting Part Zero: establishing the datum this correction is measured against.
- Volumetric Compensation: the machine’s own geometry, corrected once at commissioning.