|

From CAD to CNC: How to Prepare Technical Drawings for CNC Machining

ByCraftcloud Blog

If you are uploading your model to Craftcloud® to have it CNC machined, in addition to the STEP (or .STP) file, adding a 2D technical drawing can be key. While the former can provide the part’s geometry, the latter is important to communicate specific tolerances, thread details, and internal features.

A Must

A 2D technical drawing is the only way to accurately communicate:

  • Threads: The internal or external thread sizes and depths have to be specified.
  • Tolerances: Any dimensional deviations that have to be tighter than the machine’s standard tolerance can be communicated here.
  • Surface finish: Roughness requirements for particular faces can be specified.
  • Geometric requirements: Geometric Dimensioning and Tolerancing (GD&T) symbols can be used to define flatness, parallelism, or concentricity.

What to Include

For best practices, the following should be part of your 2D technical drawing:

  • Title block: Including the part name, material, scale, and measurement system (Metric vs. Imperial).
  • Orthographic views: 2D “front, top, and side” views to display main dimensions.
  • Isometric view: A 3D pictorial can help the machinist quickly visualize the final part’s geometry.
  • Section and detail views: Section views for internal cavities and detail views (magnified areas) for complex, small features.

Keep in Mind

The following will help you in your workflow:

  • Define datums: Select common baseline surfaces to ensure uniform dimensioning.
  • Dimension critical features first: Focus on dimensions essential for the part’s function (e.g. where it fits with another part).
  • Add construction lines: Include centerlines for symmetry and center marks for hole locations.
  • Hole callouts: Instead of dimensioning every aspect of a hole, use a callout to specify diameter, depth, and whether it is a counterbore or countersink.

Uploading the 2D drawing in PDF is best, to ensure the technical specifications remain unchanged from the moment you create them to the moment our manufacturing partner receives it. And naming it the same as your project or as the 3D model can also help prevent confusion.

Similar Posts