Process
How a route sheet is built, stage by stage, and the arithmetic behind the numbers on it.
Stage 1
Face — establishing datum.
Everything else on the drawing is measured from a surface, not from the raw casting or bar stock. Facing cuts that surface true and flat first, so every operation after it is measuring from a real, known plane rather than compounding whatever error the sawn stock started with.
Stage 2
Pocket — roughing to shape.
A ball-nose or bull-nose cutter rasters back and forth, removing the bulk of the material a bit at a time. The scallop the calculator below computes is not a flaw to hide — it is the honest signature of how far apart the passes were set, and it is what a finishing pass exists to remove.
The calculator
Scallop height, worked out live.
Scallop height: —
Last stage, always
Inspect — the part reports on itself.
A CMM touches the part at the points the drawing's GD&T frames call out and compares the result to the nominal. That report travels with the lot. If a dimension is out, we know before the part ever leaves the building — not when a customer's incoming inspection finds it.