Make the important features clear
A CNC drawing should identify the surfaces and dimensions that control how the part works. Show datums, fits, threads and critical relationships rather than applying the same tight tolerance to every feature. Include the current model, part number and revision.
Give the cutter access
Milling cutters rotate, so internal corners generally retain a radius. Deep pockets, narrow slots and features reached from several directions can require smaller tools, longer reach or additional setups. Review access and workholding while the geometry is still easy to change.
Consider setup and inspection together
Features on opposing faces may depend on how the part is located between operations. Identify the datum scheme and the relationships that matter to the assembly. Discuss the measurement approach for features that are difficult to reach or inspect.
Specify holes and threads completely
State the hole size, depth and whether the hole is through or blind. For threads, include the thread designation and required engagement. Avoid leaving the manufacturer to infer these requirements from an approximate modeled shape.
Plan the finished surface
Separate cosmetic faces from functional contact surfaces. Identify the finish, any masking and whether critical dimensions apply before or after treatment. A coating can affect fit, while an as-machined finish can retain visible cutter marks.
Send a complete enquiry
Include quantity, material grade, finishing instructions and inspection requirements with the files. Point out allowable alternatives and the required delivery destination. Resolve engineering questions against one approved revision before releasing the job.