Drawings for a CNC shop

A good drawing is a contract. It says exactly what you want, so a shop can quote it accurately, make it correctly, and inspect it. A bad one starts a long email thread. Solid Vibes generates drawings from your live model and lets you tell it who the drawing is for, so it dimensions the things that matter.

1. Make the part machinable first

A drawing cannot rescue a design the shop cannot cut. Before you draw:

1. In Make, set the process to CNC Mill and the material (for example AL 6061-T6).
2. Look for tool access, sharp internal corner, undercut and small feature issues. Fix them.
3. Give inside corners a radius slightly larger than the cutter (3.2 mm for a 6 mm tool is common).

See Designing for CNC machining for the reasoning.

2. Say what the drawing is for

This is the "dimension for a purpose" idea. A drawing for a CNC shop emphasizes machined features, tolerances and finish. A drawing for assembly instructions emphasizes how pieces go together. Tell the agent:

Make a drawing of this bracket for a CNC shop. Material AL 6061-T6, 6 mm plate. Dimension every hole and pocket. Default tolerance +/-0.1 mm, and +/-0.05 mm on the two 8 mm bore holes. Deburr and break sharp edges. Anodize clear.

An auto drawing sheet costs 5 credits in Fast and 8 in Smart by default.

3. What the drawing should contain

Solid Vibes produces front, top, side, section, detail and isometric views as needed, with:

• Dimensions chosen for the purpose you named, so a shop drawing dimensions machined features first,
• Tolerances, general and specific,
• GD&T frames when you ask for them (flatness, position, perpendicularity),
• Hatching on section views,
• Notes for material, finish and treatment,
• A title block with part name, revision, material, units and date,
• ISO or ANSI standard conventions. Pick the one your shop uses.

For multiple pieces, you can produce a multi-sheet set: a drawing per piece, one for the whole Thing, and an exploded view with a parts table.

4. Review like an inspector

Read the sheet as if you were machining it:

Ask the agent to review it too:

Review this drawing as a machinist would. What is missing, ambiguous or likely to make the quote expensive?

5. Live drawings and revisions

Drawings are live: they update when the model changes. So when you change plate_thickness from 6 to 8 mm, the dimensions, views and title block follow. Revisions are tied to release tags, which means "Rev B" in the title block corresponds to a frozen version of the model. Tag the commit when you send a drawing out.

6. Export and send

Send both of these:

• PDF drawing. The shop reads dimensions, tolerances and notes from it.
• STEP file. The shop cuts from the exact 3D geometry.

Where the 2D profile is needed for laser or waterjet, also send a DXF (DWG is available via conversion).

7. Get a quote

Ask your shop for a quote with your PDF and STEP attached. Tell them quantities, material source (if you have one), and your deadline.

Common questions

Do I need GD&T? Only where function needs it. Position, flatness and perpendicularity on key surfaces are enough for most parts. For simple parts, plain tolerances are fine.

What is the best general tolerance? Ask your shop for their standard. ISO 2768-m (medium) is a widely used default for machined parts.

Can I get a drawing in inches? Solid Vibes works in millimetres, and drawings are dimensioned in millimetres. Most shops convert without trouble, but tell them the units up front.

Try it

On the L-bracket template:

Prepare this bracket for CNC from 6 mm aluminum plate: radius all inside corners to 3.2 mm, then make a three-view drawing with an isometric, dimensioned for a CNC shop. Tolerance +/-0.1 mm general. Add a note: break sharp edges 0.3 mm.