AutoCAD ACU common mistakes
AutoCAD ACU · Understand the traps and how to avoid them.
Starts a new drawing with QNEW and accepts whatever template loads (often the unitless imperial acad.dwt), then types metric values such as a 100 mm plate and gets geometry at the wrong size; block inserts also come in at the wrong scale.
QNEW silently reuses the default template set in Options, so the candidate never consciously chooses units. With insertion units either unset (INSUNITS 0) or mismatched to the block's defined units, AutoCAD inserts blocks 1:1 or 25.4:1 off.
What to do instead
Use File > New and explicitly pick the template (acad.dwt for imperial, acadiso.dwt for metric); verify units with the UNITS dialog and set a real INSUNITS value (e.g. 4 = millimeters, 1 = inches) so block insertion scaling is automatic; if a block still comes in wrong, re-enter INSERT and type the scale factor instead of accepting 'Specify On-screen'.
Builds a standard layer set, dimension style and title block in a normal DWG, then expects every new drawing to inherit them; the next QNEW comes up blank and the candidate rebuilds everything under exam time pressure.
The setup work was saved with QSAVE as a .dwg in the project folder. Drawing templates are .dwt files stored in the template path, and only files in that location appear in the Select Template dialog.
What to do instead
Use SAVEAS, choose AutoCAD Drawing Template (*.dwt), save into the template folder, then set it as the default via Options > Files > Template Settings > Default Template File Name for QNEW (or just pick it from the New dialog each time).
Holds Shift while clicking a second and third object to build a selection set, and watches previously selected objects drop out of the set.
In AutoCAD, Shift+click is the subtract-from-selection modifier, not the add modifier. The habit comes from other graphics and office software where Shift extends a selection.
What to do instead
Click additional objects with no modifier to add them; use Shift only to deselect. For grouped picks use a window/crossing window, or type SELECT and use the Add/Remove options if you need explicit control.
Tries to lengthen one end of a line with STRETCH by dragging a left-to-right window over the whole line, and the entire line translates instead of stretching.
A standard (left-to-right) window selects only objects fully enclosed and moves them as a unit. Only a crossing window (right-to-left) picks up objects partially inside so that the endpoints inside the window move while the others stay put.
What to do instead
Start the STRETCH selection with a right-to-left drag (crossing window) and enclose only the endpoints you want to move; confirm the crossing highlight appears before pressing Enter. Remember vertices of fully enclosed objects move, and objects fully outside the crossing window are untouched.
Assigns colors, linetypes and lineweights directly to individual objects instead of leaving them ByLayer, then cannot answer why changing the layer's color does nothing to those objects.
An explicit object property always wins over the layer's property. Candidates set object color to make a quick visual check and forget to reset it, so the drawing's layer standard is broken and property queries return unexpected values.
What to do instead
Select the objects and set Color, Linetype, Lineweight and Plot Style back to ByLayer in the Properties palette, or use the ByLayer button in each drop-down before picking; audit with the LAYTRANS or a QSELECT of objects whose color is not ByLayer.
Makes a layer current, turns it off to 'hide clutter', keeps drawing, and then reports that new objects are not being created because nothing appears.
The current layer can be turned off (AutoCAD allows it, unlike freezing), and everything drawn on it is immediately invisible. Candidates confuse the Off, Freeze and Lock columns, which look similar in the Layer Properties Manager.
What to do instead
Learn the distinction: Off hides but keeps objects live, Freeze also skips regeneration (and cannot be applied to the current layer), Lock prevents editing while keeping objects visible. Use VP Freeze inside a viewport for layout-only hiding, and check that the current layer's icons are all clear before drawing.
Creates dimensions in model space at 1:1, sets a layout viewport to 1:2, and finds the dimension text and arrows plot at twice the intended size overlapping the geometry.
Non-annotative dimension styles use a single fixed DIMSCALE, so the annotation size is baked in at creation time and does not follow the viewport scale. Candidates assume dimension text auto-adjusts the way viewport scale does for annotative objects.
What to do instead
Either make the dimension style annotative and add the required scales (set the annotation scale in model space and in the viewport), or set DIMSCALE equal to the reciprocal of the viewport scale factor before dimensioning (DIMSCALE 2 for a 1:2 viewport). Verify with REGENALL after changing scale.
Double-clicks inside a layout viewport, uses the mouse wheel to make the drawing fit, and then cannot reproduce the stated scale; later a stray pan shifts the view and the drawing has to be re-aligned.
Zooming with the wheel inside a viewport overrides the standard scale, and the wheel also activates the viewport, so navigation gestures silently leave the view in an arbitrary state. The candidate never locks the viewport afterwards.
What to do instead
Set scale from the Viewport Scale list on the status bar or in the Properties palette (Standard scale, e.g. 1:50), not by zooming. Then set Display Locked = Yes on the viewport so pans are restricted to panning the view without changing magnification, and use PAN only outside the viewport when adjusting the sheet.
Runs HATCH, picks an internal point, gets the 'A closed boundary cannot be determined' message, and keeps re-picking the same point or falls back to manually selecting line after line; also accepts a default scale that produces either a solid black blob or an invisible pattern.
Hatch needs a truly closed boundary, and tiny gaps, overlapping duplicate lines, or geometry on a frozen/off layer break boundary detection. Pattern scale is also drawing-unit dependent, so the default 1.0 is meaningless in a millimeter drawing.
What to do instead
Zoom in on the corners to close gaps (use FILLET with radius 0 or EXTEND/TRIM), delete duplicate overlapping segments, and make sure boundary geometry is visible. Then use Pick internal point with Island detection set as required, and set HPSCALE relative to drawing units (e.g. 10-50 for a millimeter drawing) and check the preview before committing.
Hits Plot from the Model tab with 'Fit to paper' checked and no page setup, producing a sheet whose scale is arbitrary and whose lineweights and colors do not match the office standard; or plots a layout with 'Plot with plot styles' cleared so everything comes out with default thin lines.
Plot settings are stored per layout in a page setup, and model space plotting requires an explicit scale. The 'Fit to paper' and 'Plot with plot styles' checkboxes are easy to leave in the wrong state because they persist from the previous plot and are not obvious in the dialog.
What to do instead
Use PAGESETUP to create and name a page setup per layout, then Page Setup > Modify and set the plot device, paper size, Plot scale 1:1 for layouts (or the explicit scale for model space with Fit to paper off), the correct CTB/STB plot style table, and 'Plot with plot styles' checked. Confirm with Preview before plotting.