ACP AutoCAD common mistakes
ACP AutoCAD · Understand the traps and how to avoid them.
Selecting objects first and then invoking TRIM or EXTEND, so the selection set is treated as cutting/boundary edges and the command prompts for objects to trim instead of trimming immediately.
Candidates carry over the habit of pre-selecting everything before a command, but TRIM and EXTEND invert the usual select-then-act order; the first selection is the boundary set, which surprises test-takers under time pressure.
What to do instead
Start TRIM or EXTEND with nothing selected, press Enter at the 'select cutting edges' prompt to use all objects as edges, then click the segments to remove. Alternatively use the Quick mode, where you simply hover and click the portion to trim.
Drawing a closed boundary with separate LINE segments that leave tiny gaps or overlaps, then finding HATCH fails with 'valid hatch boundary not found' or produces an unexpected island.
Candidates draft with LINE because it feels faster, not realizing HATCH needs a truly closed, non-self-intersecting boundary; sub-pixel gaps are invisible on screen.
What to do instead
Use PLINE with the Close option, or run BOUNDARY to generate a closed polyline from the enclosed area, then hatch that object. Zoom in to verify closure with object snaps before hatching.
Editing model geometry on the Model tab and expecting the sheet annotations, dimensions, or title block to move with it, then finding the layout unchanged or misaligned.
Candidates do not distinguish model space from paper space, so they treat viewport scale as if it were a simple zoom and edit the wrong space for the task.
What to do instead
Do geometry edits in model space, then use the viewport's standard scale list or Zoom XP to reset scale; put dimensions and notes in paper space only when they annotate the sheet, and lock viewports (Display Locked) so panning cannot alter scale.
Double-clicking inside a viewport to pan or zoom the drawing, which changes the viewport scale and throws off annotation sizes and plotted scale.
The wheel-zoom reflex is strong, and candidates do not notice the viewport is unlocked, so a harmless-looking pan silently rescales the view.
What to do instead
Lock each viewport after setting its scale (Properties palette, Display Locked = Yes) and pan by moving the viewport frame rather than zooming inside it. Check the scale in the viewport's status bar or Properties before plotting.
Inserting a block and then editing the original geometry in place, expecting every insertion to update, but only the single reference changes or nothing does.
Candidates confuse editing an inserted block reference with redefining the block definition, so they edit the wrong object or use the wrong command.
What to do instead
Use BEDIT (or the Block Editor) to change the definition, save it, and all references update. To change only one instance, use REFEDIT or explode a copy deliberately.
Creating attributes as plain TEXT inside a block, or forgetting to set the attribute mode or order, so values cannot be extracted and the block shows no prompts on insertion.
Candidates build blocks quickly from existing text and do not know that only ATTDEF objects become attributes; they also overlook ATTDIA and attribute order settings.
What to do instead
Define attributes with ATTDEF before creating the block, choose modes (Invisible, Constant, Verify, Preset), set the order with BATTMAN, and verify by inserting the block and running ATTEXT or DATAEXTRACTION to confirm the tags are captured.
Attaching an external reference with a full absolute path, then submitting or plotting from another machine or folder where the drawing opens with unresolved xrefs.
The default attach type is often a full path, and candidates never test the drawing from a different location, so the fragility of absolute paths stays hidden until delivery.
What to do instead
Attach xrefs with Relative path, keep the xref and host drawing in a consistent folder structure, and use Reference Manager or the eTransmit tool to repath and package files before handing off.
Editing the xref source file directly during a session and assuming the host drawing updates only after reopening, or binding an xref when the intent was to keep a live link.
Candidates do not understand that xrefs load at open time and that BIND converts the xref into a local block, permanently breaking the external link.
What to do instead
Use XREF Reload to refresh after source edits, and reserve XBIND or BIND for final delivery when a self-contained file is required. Confirm with the XREF palette whether each reference is Attached or Overlay.
Plotting without checking the page setup: plotting from model space with a wrong scale, or plotting a layout with the wrong paper size, plot area, or plot style table, producing clipped or faint output.
Candidates trust the default page setup and do not preview, and they confuse 'Fit to paper' with a true plotted scale.
What to do instead
Open Page Setup Manager, set paper size, plot area (Layout or Window), scale (1:1 for layouts), and the correct CTB/STB plot style, then always use Preview before Plot. Save the setup so it is reused.
Leaving lineweights, transparency, or plot styles that display correctly on screen but plot wrong, such as missing lineweight in the CTB or annotation at a tiny plotted size.
Candidates judge output by the on-screen display, where lineweight display and plot style tables are not necessarily active, so the difference between display and plot goes unnoticed.
What to do instead
Enable Show/Hide Lineweight and Plot Style preview, assign lineweights through layers or the plot style table rather than object overrides, and check the plotted result with Preview or a PDF before final submission.