ENGT122 - CADI

1. ENGT122 - CADI Chapter 13 - Hatching

2. What is Hatching? • Hatching refers to filling an enclosed boundary with a repetitive pattern of formatted line segments. • Hatching in AutoCAD is the same as creating section lines in drafting. • Typically used to identify cut region of a part in a Section View. • Also used to distinguish parts or identify materials in sectioned assembly drawings.

3. Example - Hatching • Examples of hatching section views in AutoCAD

4. DEMO 1: • Load file Demo1.dwg. • Create a quick hatch for reference.

5. Hatch Patterns spacing • AutoCAD provides numerous predefined hatch patterns. • Each hatch pattern is defined by individual line segments with specified pattern, angle, and spacing. • For convenience, the line segments in each hatch are stored and treated as a group.EXPLODE will break the hatch into individual segments. angle pattern

6. Hatch Boundary • Hatching should be performed on drawing regions completely enclosed by a boundary – Hatch Boundary. • The Hatch Boundary may consist of lines, arcs, circles, or other entities. • AutoCAD does not require the objects comprising a Hatch Boundary to be connected point to point. Any intersecting entities which form an enclosure will work. Hatch Boundary

7. Creating a Hatch Command to create hatch patterns; • HATCH • Uses graphical dialog box. • Boundary defined by; • Selecting point within an enclosed region; or by • Selecting boundary objects. • Allows preview of hatch pattern. • Allows associative hatching.

8. HATCH HATCH can be invoked by 3 methods; • Command:HATCH • DDMenu:Draw>Hatch… • Draw Toolbar All 3 bring up the HATCH dialog box.

9. Hatch Patterns Selecting a Hatch Pattern: • TYPE – sets the hatch pattern type. • Predefined - Specifies a standard pattern supplied with AutoCAD. Angle and Scale can be controlled by user. • User Defined - Creates a user defined pattern of lines. Covered in CAD III. • Custom - Specifies a custom pattern created by user and stored in a hatch file (.pat). Covered in CAD III.

10. Hatch Patterns PredefinedHatch Pattern: • Drop down shows listing of available hatch pattern names. • […] Displays graphical image of available patterns according to groupings; • ANSI – patterns defined by American National Standards Institute. • ISO – patterns defined by International Standards Organization. • Other Predefined – other AutoCAD Patterns. • Custom – custom pattern from user file. Typically use this Pattern (ANSI31).

11. Scale=1 Angle=0 Scale=0.5 Angle=0 Scale=1 Angle=45 Scale=0.5 Angle=45 Hatch Pattern Definitions Effect of Angle & Scale: • The hatch pattern line segment lengths, spacing, and angle are predefined. • However, Angle and Scale can be altered. • Angle – rotates hatch with respect to definition angle. • Scale – scales hatch segment length & line spacing with respect to defined length & spacing.

12. DEMO 2A: • Load file Demo2.dwg • Show various predefined patterns. • Show effect of Angle and Scale. • Show Exploding Hatch.

13. Selecting Boundaries • Hatch Boundaries can be selected by 2 methods; • Pick Points – AutoCAD automatically constructs a boundary from the smallest enclosure surrounding the picked point. • Select Objects – requires selecting the objects to be hatched.

14. Pick Point Pick Point Pick Point Selecting Boundaries Pick Points: • Constructs a boundary from the smallest enclosure surrounding the picked point. • Uses island detection to remove regions completely enclosed within the boundary.

15. Pick Point Pick Points Selecting Boundaries Pick Points: • Multiple pick points can be used to add islands or additional areas to the hatch region.

16. Exercise 1: • Create the RED circles and rectangle shown in A. Then make 2 additional copies as shown in green. • Use Pick Points to hatch each figure as shown in B using the ANSI31 hatch pattern. Use the Scale option to get a reasonable hatch spacing. Figure A Figure B

17. Island Detection • Expanding the Hatch Dialog box gives access to some Island Detection Options…

18. Island Detection Pick Points Normal Island Outer Island Ignore Island

19. Island Detection Selection Short-cut Menu: • The Island Detection Options can also be accessed through a shortcut menu (Right click mouse during point selection). • Recommendation: Only use the Enter button on the shortcut menu. There are bugs associated with the shortcut menu – particularly with the Preview button. Use Preview on the main dialog box. Don’t Use Shortcut Preview!!! Avoid this - bug

20. Exercise 2: • Make 3 copies of the circle and ellipse pattern as shown in A. They should be perfectly centered. • Use a single Pick Point with the correct Island Detection Option to hatch each figure as shown in B. Use the ANSI31 hatch pattern and the Scale option to get a reasonable hatch spacing. Figure A Figure B

21. Selecting Boundaries Select Objects • Constructs a boundary from selected objects. • Does not recognize interior objects unless they are selected as well. • More limiting than Pick Point method – not all hatch patterns can be achieved.

22. Selecting Boundaries Select Objects • Examples of Select Object Method Select Object Select Object Select Object

23. Exercise 3: • Make 3 copies of the circle & rectangle pattern as shown in A. • Use Select Objects to hatch each figure as shown in B using the ANSI31 hatch pattern. Use the Scale option to get a reasonable hatch spacing. Figure A Figure B

24. Miscellaneous Hatch Options • Remove Boundaries – allows boundaries such as islands to be removed from selection set. • View Selection –temporarily closes dialog box so object selection can be viewed.

25. Miscellaneous Hatch Options • Inherit Properties – allows hatch pattern properties from a hatched object to be transferred to another selected objects. • Associative – hatch pattern will update if boundary geometry is changed. • Create Separate Hatches - for multiple selections, each hatch is is treated as a separate object.

26. DEMO 3: • Load file Demo2.dwg • Show Associative vs. Nonassociative Hatch pattern. • Show Create Separate Hatch • Show Inherit Properties

27. Exercise 5A: • Create the 3 green rectangles as shown. • Then hatch them using the hatch patterns indicated…don’t worry about the color but note the angle on the 1st and 3rd hatch pattern. Make sure the Associative option is selected. Predefined AR-B816C Predefined ANSI 31 Predefined ANSI31

28. Exercise 5B: • Create 3 overlapping circles as shown in FigB. • Then hatch them using the Inherit Option to transfer the hatch patterns from FigA. Figure A Figure B

29. Exercise 5C: • Use Grips to adjust the image in Fig A to that shown in Fig B. Note how Associative Hatch works! • If you have problems creating the small circle, try making it larger instead. Figure A Figure B

30. Hatching Around Text • For hatching, AutoCad treats text like any other object. • The same rules for Island Detection and Selection still apply. • This prevents section lines (hatch pattern) from overlaying text if treated properly…as you remember from Drafting this is usually desired. • If Object Selection is used, the text as well as the geometry must be selected to prevent an overlay.

31. Editing Hatches • Once created, a hatch can be edited to change most all of its attributes except for the boundary. • Editable items include; • Change Pattern • Change Angle • Change Scale • Change Composition from Associative to Nonassociative, but not vice versa. • Change Island Detection Style (this may change the hatch area depending if islands are present).

32. Editing Hatches Short-Cut Menu Methods to initiate a Hatch Edit: • Select hatch, then right click mouse and select Hatch Edit from the short-cut menu. • Double-Click directly on the hatch object. This is the quickest & easiest method. • Both methods bring up the Boundary Hatch dialog box where edit changes can be made.

33. Final Notes For future assignments use the following settings: • Section lines (ANSI31 pattern – adjust angle as necessary): • Line weight = 0.35 mm • Color = Cyan • Linetype = Continuous • Cutting Plane Lines: • Line weight = 0.7 mm • Color = Magenta • Cutting Plane Linetype = Hidden or Phantom with CELTSCALE adjusted to get proper segment lengths. • View Arrows = Continuous lines. Use Polyline to create arrow. Length to width ratio = 3.

34. End Lesson 28

35. The End!

36. RETIRED MATERIAL

37. Example - Hatching • Example of hatching section view in an Assembly.

38. Hatch Patterns Selecting a Hatch Pattern: • TYPE – sets the hatch pattern type. • Predefined - Specifies a standard pattern supplied with AutoCAD. Angle and Scale can be controlled by user. • User Defined - Creates a pattern of lines based on the current linetype in your drawing. Angle and Spacing can be controlled by user. Double creates additional lines at 90 to first set. • Custom - Specifies a custom pattern created by user and stored in a hatch file (.pat). Won’t need this until CAD III.

39. First hatch line DY offset (X-origin, Y-origin) Behind the Scene How Hatch Works: • AutoCAD creates the first hatch line of infinite length through an origin specified in the hatch definition. • Additional infinite hatch lines are then offset from first (DY). • Using the user selected hatch boundary, the intersection of the boundary and the infinite hatch lines are identified. • All hatch segments outside the boundary are then turned off. Full Screen External hatch turned off

40. Hatch Pattern Definitions User Defined Hatch: • Uses the linetype set for the current layer. • User specifies Angle and hatch line Spacing. • Selecting Double creates additional lines at 90 to first set

41. DEMO 2B: • Load file Demo2.dwg • Show how to make a User Defined Hatch pattern.

42. Exercise 4: • Create the circle and rectangle pattern shown in A. • Create a new layer with linetype=hidden and color=yellow, then make it current. • Use Select Objects to hatch the figure as shown in B using a User Defined hatch with an angle of -30. Adjust Spacing to achieve a pattern as shown. • If necessary, use the line scale commands (LTSCALE) to adjust dash length. AS TIME PERMITS Figure A Figure B

43. Selecting Boundaries Selection Short-cut Menu: • Right clicking the mouse during point selection displays a short-cut menu. • To remove selection boundaries. • Changes Island detection method • Allows Preview, but has a bug! Pick Points Avoid this - bug Normal Island Outer Island Ignore Island

44. Advanced Tab • The Advanced Tab allows some additional options. Island Detection Style: allows Island Detection Default to be set. Object Type: determines object type created from boundary (polyline or region) and whether its retained. Boundary Set: sets items to consider for boundary. Island Detection Toggle: island detection on or off. Includes Islands Excludes Islands

45. Advanced Tab Normal Outer Ignore • Review of Island Detection Styles *Note: white arrows indicate pick point.

46. Selecting Boundaries Select Objects • Constructs a boundary from selected objects. • Does not recognize interior objects unless they are selected as well. • More limiting than Pick Point method – not all hatch patterns can be achieved.

47. Selecting Boundaries Select Objects • Examples of Select Object Method Select Object Select Object Select Object Pick Points Can’t recreate the Pick Point hatch pattern Select Object

48. Pick Point Pick Points Selecting Boundaries Pick Points: • Multiple pick points can be used to add islands to the hatch region. • AutoCAD creates a polyline to represent the boundary formed by the enclosure and islands. • By default the polyline is deleted after the hatch is created. But it may be retained through settings in the Advanced tab.

49. DEMO: • Load file Demo3.dwg • Show Retained Object option and whether polyline or region is retained.

50. Gradient Tab • Provides color shading for graphical enhancement. • Demonstrate. AS TIME ALLOWS