CNC routing can combine several controlled operations in one sheet part. Standard materials are MDF, moisture-resistant MDF and structural plywood, subject to project review. The maximum stock size is 1220 × 1220 mm and the usable cutting area is smaller. The drawing must still distinguish what cuts through, what stops at a depth and which side is being machined.
Operation map
- Profile: the finished outside boundary.
- Internal cut-out: a removed opening through the sheet.
- Pocket: an area machined to a specified depth.
- Rebate or dado: a pocket used at an edge or as part of an assembly.
- Hole or slot: a located feature whose size and fit purpose matter.
- Engraving: a shallow line or recessed detail whose legibility depends on cutter, depth and material.
See the plain-language operation definitions.
Cutter constraints
A round cutter leaves an internal radius and cannot enter a space narrower than itself. Very small lettering, narrow islands and deep thin slots may be fragile, unmachinable or disproportionately slow. Understand cutter diameter and detail size.
Mark up the part
Use a top view plus section views where depth could be ambiguous. Label through-features, pocket depths, front/back, visible face, critical dimensions and the object or part that must fit.
Combination operations and cost
A design using different cutter sizes may require extra setup, checking and tool changes. A second cutter can be justified when it protects function or appearance; it should be a conscious trade-off. See how tool changes affect cost.
A section view prevents expensive ambiguity
Top views show boundaries but often hide depth. Add a simple section through every feature whose depth or face cannot be inferred safely. Label the top/reference face, material thickness, pocket floor and through opening. For a stepped feature, show each level rather than combining several values in a note. Technical buyers can provide this in the drawing package; novices can sketch the cross-section and mark known dimensions. Either route is clearer than asking the workshop to choose what “recess this area” means.
Translate the sketch into CNC operations
When a sketch contains an outer shape, an internal opening, a shallow recessed logo panel and a slot, describing everything as a “cut” leaves the production scope unclear. Naming each operation and depth makes feasibility and quotation review more reliable.
Specify faces, depths and fits
| Decision | Evidence to use | Consequence |
|---|---|---|
| Profile | Mark the intended finished outer boundary. | Inside/outside interpretation is not guessed. |
| Show boundary, depth and reference face. | A blind recess cannot become a through opening. | |
| Slot | Provide width, length, end form and purpose. | Cutter access and fit can be reviewed. |
| Engraving | Supply full-size artwork and legibility need. | Fine detail is assessed against material and finish. |
Operation-markup mistakes to avoid
Depth appears only in a filename.
Put it on a readable operation drawing linked to the part revision.
A hole is dimensioned without its function.
State clearance, location or hardware relationship so the method can be chosen.
Back-face work is mirrored accidentally.
Use face labels, orientation marks and a section/assembly view.
Combined operations imply one cutter.
Review each feature group and justify tool changes instead of promising a one-tool result.
Operation-markup checklist
- Use one top view and needed sections.
- Name profile, cut-out, pocket, slot and engraving.
- State all depths from a named face.
- Mark units and check dimension.
- Show cutter-critical small details.
- Identify visible edges and face.
- Provide hardware and fit purpose.
- State material and quantity.
CNC capability questions
Is a pocket the same as engraving?
Both remove partial depth, but a pocket clears an area while engraving commonly follows lines or detail; their tools and finish can differ.
Can CNC make square internal corners?
A round cutter leaves an internal radius; relief or changed mating geometry may be needed.
Are holes always drilled?
No. The chosen method depends on size, depth, tool and material; specify finished need rather than assuming the process.
Confirm operations for the active geometry
The quotation confirms which operations are feasible for the active geometry, material and tooling. Minimum details, fits and critical dimensions should be tested where the consequence of error justifies it rather than inferred from a generic example.
Send a marked-up part
Send a marked-up part or sketch. Exact tool and operation availability remains subject to review.