What this is
A flush-screw finish is what you reach for when the screw head can't be left sitting proud of the surface. Where the screw head needs to sit level with the panel surface — visible installations, walk-on surfaces, cabinet doors, signage where the fix has to look intentional — the hole gets countersunk. The chamfer matches the angle of the screw head; the depth lets the head drop flush.
We countersink on the CNC as a separate operation in-line with the drill and cut steps. Standard profiles are 82° (imperial countersunk screws), 90° (metric countersunk screws), and 100° (specialist flat-head). 90° is the most common request — it matches almost all the metric countersunk fasteners on the Australian market.
For your file, mark countersunk holes on a separate layer labelled CSK-XMM-Y° (where X is the through-hole diameter and Y is the chamfer angle). The naming is just a label — if you're not sure of the angle, write the screw spec ("M5 countersunk machine screw") and we'll match.
Countersinking pairs naturally with drilling and tapping. For tapped countersunk holes (threaded engagement with a flush screw head), specify both — the workflow is drill-tap-countersink on the same hole. Common in fabricated assemblies, machined fixtures, and detailed signage where the look matters.