CAD Software Operation and File/Environment Management
Environment setup
Start from a template (.dwt) with millimetres, a layer scheme, text and dimension styles, and a title block. Model space is 1:1; paper-space layouts carry the sheet and viewports. Name layers by function-OUTLINE, HIDDEN, CENTER, DIM, HATCH, TEXT-and assign colour, linetype and lineweight by layer rather than by object.
File and reference control
DWG is the native format; DXF is the exchange format. Keep xrefs on a server path, use relative paths, and bind or eTransmit them before sending a package. Run AUDIT/RECOVER on damaged files, keep .bak and autosave files, and PURGE unused blocks and layers before archiving. Do not explode dimensions or blocks; it destroys associativity and bloats the file.
Worked example
A detail must plot at 1:2 on A3. In model space draw the part full size. In the layout, create a viewport at scale 1:2, lock it, and set the annotation scale of dimensions and text to 1:2 so 3.5-mm plotted text is 7 mm in model space. If the dimension style is left at 1:1, the plotted text measures 1.75 mm and fails the minimum text height. The reasoning is that plotted size = model size × viewport scale; annotation scale compensates in the opposite direction.
Traps
Drawing a 1:2 part at half size in model space, putting geometry on layer 0, leaving xref paths absolute, plotting from model space with “fit to paper”, and failing to purge or bind before delivery.