SOFTWARE LAB (AutoCAD) (CE-406) - Unit 2 Short Notes

UNIT 2: FUNDAMENTAL 2D DRAFTING & EDITING TOOLS

2.1. Precision Drafting Techniques

• Coordinate Systems:

  • Absolute (Cartesian): X,Y from origin (0,0). e.g., 10,5.

  • Relative (Rectangular): @ΔX,ΔY from last point. e.g., @5,3.

  • Relative (Polar): @distance<angle from last point. e.g., @10<45.

  • Direct Distance Entry: Move cursor to define direction, type distance.

• Object Snaps (OSNAP): Single-use (type first letter: END, MID, CEN, QUA, INT, PER, TAN, NEA) vs. Running OSNAP (permanent, set in status bar).

• Polar Tracking: Guides cursor at specified angles (e.g., 90°, 45°). Set increment angle.

• Object Snap Tracking: Uses OSNAP points as temporary tracking points to align with.

• Grid & Snap: Grid is visual reference; Snap restricts cursor to grid points. Set spacing independently.

• D Commands: DDIM (Dimension Style), DIMSTYLE (same), DIMSCALE, DIMEXE (extension line offset).

[!TIP] Common Pitfall: Confusing Grid (visual aid) with Snap (cursor restriction). Use both for precision.

2.2. Creating Geometry: Basic Drawing Commands

2.3. Modifying Geometry: Core Edit Commands

• Erase (ERASE): Select objects. Use UNDO (U) immediately after.

• Copy (COPY): Creates duplicates. Base point then displacement or second point.

• Mirror (MIRROR): Reflects across a line. Delete source objects? (Y/N).

• Offset (OFFSET): Creates parallel object at specified distance. Through point option.

• Trim (TRIM): Cuts objects to a cutting edge. Select cutting edges first, then objects to trim.

• Extend (EXTEND): Extends objects to a boundary edge. Select boundary first.

• Break (BREAK): Removes part of object between two points. BREAK at point (F option) removes one side.

• Join (JOIN): Connects end-to-end lines, arcs, polylines into single polyline.

• Fillet (FILLET): Creates arc or radius 0 to join. Multiple (M) option.

• Chamfer (CHAMFER): Creates beveled edge. Set distances (D1, D2) or angle (A).

• Stretch (STRETCH): Use crossing window to select. Moves endpoints within window, leaves others.

• Scale (SCALE): Base point + scale factor or reference length (R).

• Rotate (ROTATE): Base point + angle or reference (R).

• Move (MOVE): Simple displacement.

[!TIP] Exam Trap: STRETCH vs MOVE. Crossing window (right-to-left) for stretch; Window (left-to-right) for move/select.

2.4. Object Properties & Organization

• Layers (LAYER): Primary organizing tool.

  • States: On/Off, Freeze/Thaw (in all viewports), Lock/Unlock.

  • Color, Linetype, Lineweight can be set ByLayer (default) or ByObject.

• Layer States Manager (LAWSTER): Saves/restores layer settings (on/off, color, etc.).

• Linetype Scale (LTSCALE): Global scale for linetypes. PSLTSCALE controls paper space scaling.

• Properties Palette (Ctrl+1): Quick edit of any object's properties.

• Match Properties (MATCHPROP): Copies properties (color, layer, etc.) from source to destination objects.

2.5. Blocks, Attributes & External References (XREFs)

• Creating Blocks (BLOCK):

  1. BLOCK command.

  2. Name block.

  3. Base point (insertion point) – critical!

  4. Select objects.

  5. Choose Retain, Convert to block, or Delete.

• Inserting Blocks (INSERT):

  • Specify block name, insertion point, Scale (X,Y,Z), Rotate.

  • Explode on insertion? (Y/N) – breaks block back to components.

• Block Attributes:

  • ATTDEF: Define attribute (tag, prompt, default value) before creating block.

  • ATTEDIT: Edit attribute values of a block instance.

  • BATTMAN: Block Attribute Manager – edit tags, modes, properties globally.

• External References (XREF):

  • Attach (XATTACH): Links external DWG. Overlay vs Attach (nested vs not).

  • Manage: XREF command. Reload, Unload, Detach. Path management (full, relative, none).

[!TIP] Key Difference: Blocks are stored inside the current DWG. XREFs are external links, updated when source changes.

2.6. Dimensioning Fundamentals

• Associative: Dimensions update automatically with geometry changes (default).

• Non-Associative: Independent; must be edited manually (DIMREASSOCIATE).

• Dimension Types:

  • Linear (DIMLINEAR): Horizontal/vertical.

  • Aligned (DIMALIGNED): Parallel to object.

  • Angular (DIMANGULAR): 3-point or 2-object.

  • Radius (DIMRADIUS), Diameter (DIMDIAMETER).

  • Ordinate (DIMORDINATE): X or Y from origin.

• Dimension Style Manager (DIMSTYLE):

  • Create new style, set Primary Units, Symbols and Arrows, Text, Fit.

  • Override (DIMOVERRIDE): Temporarily change style for specific dimension.

• Editing: DIMEDIT (text, angle, location), DIMTEDIT (move dimension text).

2.7. Text & Tables

• Single-line Text (DTEXT): Each enter = new text object. Limited formatting.

• Multiline Text (MTEXT): One object, wraps, full formatting (justification, font, color, columns, fields). Use MT or T (if set to MTEXT).

• Text Styles (STYLE): Define font (.shx or .ttf), height (0 = prompt), width factor, oblique angle.

• Tables (TABLE):

  • Create from Table Style (TABLESTYLE).

  • Specify rows/columns, cell properties (data, label).

  • Edit cells: TABLEDIT or double-click.

  • Import/export via DATALINK (Excel/CSV).

2.8. Hatching & Gradients

• Hatch (HATCH):

  • Pattern: Predefined (ANSI, ISO) or user-defined.

  • Boundary: Pick points (automatic) or Select objects.

  • Associative: Updates with boundary changes (default). HATCHEDIT to modify.

  • Scale & Angle: Control pattern size and rotation.

• Gradient (GRADIENT): Solid, linear, radial, conical fills. 1-2 colors.

• BOUNDARY (BO): Creates region or polyline from enclosed area (for hatching).

2.9. Layouts & Viewports (Paper Space)

• Model Space: Infinite drawing area (1:1 scale).

• Paper Space (Layout): Represents sheet of paper. Contains Viewports (windows into Model Space).

• Layout Tab: Bottom-left. Create, rename, delete.

• Page Setup (PAGESETUP): Printer, paper size, plot scale, plot area.

• Viewport (MVIEW):

  • Create: Rectangular,Polygonal.

  • Set Viewport Scale: Double-click inside VP → ZOOM → Scale (e.g., 1:50).

  • Lock Viewport: Prevent accidental zoom/pan (MVSETUP or right-click).

  • Layer VP Freeze: Freeze layers in specific VP (LA dialog).

2.10. Plotting & Output

• Plot Command (PLOT):

  1. Plotter: Select printer/plotter or DWG To PDF.pc3.

  2. Paper Size: e.g., A4, A3, Arch D.

  3. Plot Area: Limits, Extents, Window, Layout.

  4. Plot Scale: Fit to Paper or Custom scale (e.g., 1:100). Important: In Layout, usually 1:1 (scale set in viewport).

  5. Plot Offset: Center or specify X,Y.

  6. Plot Styles (CTB/STB): Assign colors to lineweights/colors. CTB = color-dependent, STB = named.

  7. Preview: Always check.

• Save Page Setup: In PAGESETUP dialog, Add to save named setup.

2.11. File Management & Templates

• Formats:

  • .DWG – native drawing.

  • .DXF – ASCII interchange.

  • .DWT – Drawing Template (pre-set layers, styles, units, etc.).

• Creating Template:

  1. Set up drawing (layers, dimstyles, text styles, units, limits).

  2. SAVEAS → File type: DWT → Save to template folder.

• Drawing Explorer (ADCENTER): Drag-and-drop content (blocks, layers, styles) from other drawings.

• PURGE: Removes unused definitions (blocks, layers, styles). Recursive purge (-PURGE).

• AUDIT: Checks and fixes drawing errors.

2.12. Inquiry & Measurement Tools

[!TIP] AREA Tip: Use Object option for closed polylines/circles. Use Add area to sum multiple areas.