What a manufacturing drawing needs

A manufacturing drawing tells the shop everything the 3D model cannot. A good one gets you accurate quotes, fewer questions and parts that pass inspection. This guide lists what to include and how to lay it out.

Why you still need a drawing

Most shops program directly from your STEP file. The drawing is the legal and practical specification: what tolerance each feature needs, which holes are threaded, what material and finish to use, and what will be inspected. Without it, the shop has to guess, and guesses are either expensive (everything tight) or risky.

What every drawing needs

1. Views. Front, top and side views in first or third angle projection, plus an isometric view for orientation. Hidden lines where they clarify internal features.
2. Overall dimensions. Length, width and height, each shown once.
3. Feature dimensions. Hole sizes and positions, slot widths, step heights. Use a hole table or ordinate dimensions from one datum for plate parts.
4. Threads. Size, pitch, class and depth, for example M6x1-6H, 12 deep.
5. Tolerances. A general tolerance in the title block (for example ISO 2768-mK) and individual tolerances or fits on critical features.
6. Surface finish. A default roughness and finer values on functional faces.
7. Material and finish. Exact grade (for example EN AW-6082-T6) and coating (for example clear anodized Type II).
8. Notes. Edge breaks, deburring, marking and the statement that the STEP model defines the geometry.
9. Title block. Part name, part number, revision, company, scale, projection symbol, units, date and author.

First angle or third angle

Both methods use the same views, arranged differently. In first angle projection (ISO, standard in Europe), the top view sits below the front view and the right side view sits to the left of it. In third angle projection (ASME, standard in North America), the top view sits above the front view and the right side view to the right. The projection symbol in the title block, a truncated cone shown in two views, tells the reader which one is used. Misreading it mirrors the part, so always include the symbol.

Hole tables

For plate parts with many holes, a hole table is clearer than dozens of dimensions. Each hole gets a tag (A1, A2, B1…) in the view, and the table lists its X and Y position from one datum corner, its size and depth. It also matches how a machinist sets up the part: one zero point and coordinates.

Revisions

Every change gets a new revision letter, on both the drawing and the STEP file name. Mismatched revisions are one of the most common causes of wrong parts.