The definition drawing is the technical drawing that completely describes a finished part: its shape, dimensions, tolerances, material, surface finishes and treatments. It does not say how to make it, which is a matter for the manufacturing route, but what it must be. It is the reference for manufacture, inspection and acceptance, and it is authoritative between the buyer and the workshop.
A readable drawing includes several views (front, top, side, sections, details) constructed according to the rules of technical drawing (ISO 128 series), dimensions and dimensional or geometric tolerances, surface finishes (roughness), the designation of the material and treatments, and a title block. The title block gathers the designation, the number and revision index, the scale, the units, the projection method, the general tolerance (for example ISO 2768-mK) and the ownership and confidentiality notices. For an assembly, a bill of materials lists the components.
The drawing is today almost always accompanied by a 3D model in STEP format, created in CAD: the model gives the exact shape, the drawing provides what the model does not always carry (tolerances, material, requirements). If the two contradict each other, the workshop cannot guess which takes precedence: state it. Frequent errors are missing dimensions, a material written “alu” or “stainless” without a grade, no revision index, an unspecified general tolerance or a drawing that no longer matches the 3D model.
In a quote request
Supply the drawing as a readable PDF, up to date and at the current revision, with the 3D model, all named consistently (reference and revision). Have critical dimensions marked, check that the general tolerance appears in the title block, and specify which document takes precedence in case of difference. The ISO 2768 tolerances tool helps you choose the class, and the guide on file formats details what to send. Finally, think about the confidentiality of your drawings: see the non-disclosure agreement.