1. ENGT CAD I
Chapter 4 - Drawing Aids

2. Objectives • Learn the UNITS command for drawing unit setup.
• Learn to input engineering, architectural, and metric units.
• Set up and determine limits for a given drawing.
• Learn to scale a plotted drawing.
• Set up layers and assign colors and linetypes to them.
• Set up Grid, Snap, and Ortho modes based on the drawing requirements.
• Use Object Snaps and understand their applications.
• Use Autotracking and Polar Tracking.
• Determine local (CELTSCALE), and global (LTSCALE) linetype scaling factor for plotting.

3. Drawing Units In AutoCAD, drawings should always be created full size;
(1 unit in drawing = 1 unit on actual part)  Scaling only come into play when its time to plot to paper.
Before you start a drawing, decide what value each drawing unit will represent based on what you plan to draw and what system of measurement you plan to use.
Metric Ex: 1 unit = 1 mm on an actual part.
Imperial Ex: 1 unit = 1 inch on an actual part.
The easiest way to set the system of units (Metric or Imperial) is at start up using Start From Scratch in the Start Up dialog box.

4. Drawing Units
If you start a drawing in one system of measurement and then want to switch to another system, you need to resize all drawing objects by a conversion factor in order to obtain accurate dimensions that match the real object.
Ex: If you start a drawing in Imperial inches and want to work in Metric millimeters, resize all objects by a factor of 25.4.
The UNITS command controls the format of units in AutoCAD and determines;
How your coordinate and distance input is interpreted by AutoCad.
What format for coordinate input is allowed.
How coordinates and distances are displayed.

5. Units Format
Units Command – sets the format for length and angle units in your drawing.
Command: UNITS
DD Menu: Format > Units

6. Units Format Length Type: Architectural 27’-2 ¼” Decimal 326.25
Engineering 27’-2.25”
Fractional 326 ¼
Scientific E+02
For Scientific, Decimal, or Fractional, coordinates may be entered in any of these 3 formats but not Architectural or Engineering
(inch ” & feet ’ symbols not allowed).
If Architectural or Engineering are selected, coordinates may be entered in any format (the inch symbol ” is optional).

7. Units Format
Inputting Architectural, Engineering, and Fractional Units:
The input for these unit types is NOT the same as the format they are displayed by AutoCAD.
Examples:
AutoCAD Standard Optional Display Input Input
Architectural 27’-2 ¼” 27’2-1/4” ’2-1/4
Engineering 27’-2.25” 27’2.25” ’2.25
Fractional 326 ¼ /4
The inch symbol can be dropped; Numbers without foot symbol are assumed to be inches.
326-1/4 or
326.25

8. Units Format
Length Precision: - determines number of decimal points or smallest fraction which is displayed.

9. Units Format Angle Type: Decimal Deg. 34.50 Deg/Min/Sec 34d30’0”
Grads won’t use
Radians r
Surveyor N34dE
Regardless of type selected, all formats may be ued for input. Requires using the appropriate suffix and symbols, or defaults to selected input method.

10. Units Format
Angle Precision: - determines number of decimal points for displayed angles.

11. Exercise 2
Set your units to a format that allows all unit types shown to be used for input (Architectural or Engineering).
Draw the green objects.
Hint: input for 5’-2 ¼” is 5’2-1/4”
Hint: input for 5’-1.25” is 5’1.25
Global Coordinates (0,0)

12. That means: Full Scale, Full Size, 1:1, 12”=1’, etc.
Scaling CAD Drawings
One more time…CAD drawings are always created full size!
That means: Full Scale, Full Size, 1:1, 12”=1’, etc.
However, to put your full size drawing on a sheet of paper requires scaling… As Part of Your Plot Routine!
The method we use for scaling is the easiest that I know. It requires making a title block border and using it as a gage to determine the proper plot scale.
To use this method requires 2 new commands:
DIST
SCALE

13. Preparation for Plotting to Scale
2 new commands required to plot a CAD drawing to scale.
Distance Command – gives the distance between 2 points.
Command: DIST
Specify first point:
Specify second point:
Distance = …
Scale Command – changes the size of selected objects by a specified scale factor.
Command: SCALE
Select objects: pick objects to scale
Specify base point:
Specify scale factor or [Copy/Reference] <2.0000>:
*Note: format and precision of DIST is controlled by UNITS command.

14. DEMO – DIST & SCALE Open new drawing. Show DIST command.
Show SCALE command.

15. Exercise 3 Open a new drawing using Imperial units.
The standard BTC border for an A-size sheet is 10” x 7.5”. Create a rectangle 10” long by 7.5” wide as shown in A. This will represent an A-size border.
Use the DIST command to verify the approximate length & width of your border.
Use the SCALE command to double the size of your rectangle as shown in B. Then verify the dimensions using the DIST command. B
15” A
7 ½”
10”
20”

16. End Lesson 12

17. That means: Full Scale, Full Size, 1:1, 12”=1’, etc.
Scaling CAD Drawings
One more time…CAD drawings are always created full size!
That means: Full Scale, Full Size, 1:1, 12”=1’, etc.
However, to put your full size drawing on a sheet of paper requires scaling… As Part of Your Plot Routine!
General procedure for scaling a plot is the same regardless of drawing type, however there are slight differences for each of the following;
Machine drawings in English Units
Machine drawings in Metric Units
Architectural drawings

18. Scaling – English Units - Machine
Method for Scaling: - The following method is the easiest I know.
Step 1:
Start a new drawing using Start from Scratch with Imperial units.
Create your drawing Full Size using as many views as required.

19. Scaling – English Units - Machine
Step 2: Determine sheet size to use. Varies according to;
 Assigment instructions  Physical size of part
 Amount of detail on part  Company standards
 Paper/plotter availability  Etc.
U.S. Standard (in)
International (mm)
BTC uses U.S. Standard lettered sheet sizes for all plots including metric
Letter Sheet size size
A 8.5 x 11
B 11 x 17
C 17 x 22
D 22 x 34
E 34 x 44
Letter Sheet size size
A4 210 x 297
A3 297 x 420
A2 420 x 594
A1 594 x 841
A0 841 x 1189

20. Scaling – English Units - Machine
Step 3: In your drawing, generate a rectangular Border with dimensions equal to that of the Standard BTC title block border.
BTC uses ½” border margins, so Border dimensions will be 1” smaller than sheet size.
Rectangle Border Dim:
Size
A-Size
B-Size
Sheet
8½ x 11
11 x 17
Border
7½ x 10
10 x 16

21. Scaling – English Units - Machine
Step 4: Estimate the Plot Scale.
All plots must conform to a standard scale.
The following are some standard plot scales for an English (inch) machine drawing – remember this from drafting?
Use DIST to measure the length & width of your drawing. Then select a scale you think will fit the objects within the border. 15 12

22. Scaling – English Units - Machine
Step 4 Continued: Estimate the Plot Scale.
If you forget the standard plot scales you can refer to the standard scales in the AutoCAD plot dialog box.
Choose a plot scale that would reduce/enlarge your model so it fits within the full size border rectangle. Or start by choosing a plot scale closest to 1:1, either 1:2 to reduce the drawing or 2:1 to enlarge the drawing.

23. Scaling – English Units - Machine
Step 5: Determine the Plot Scale Factor .
Based on the Plot Scale you selected, calculate the Plot Scale Factor – remember this from drafting?
Plot Scale written A:B
Plot Scale Factor is A / B
Example:
Plot Scale is 1:2
Plot Scale Factor = 0.5
Plot Scale is 4:1
Plot Scale Factor = 4

24. Scaling – English Units - Machine
Step 6: Scale the border rectangle.
Use the SCALE command to scale the border rectangle by the inverse of your Plot Scale Factor.
Use the MOVE command to center the border around the drawing objects and see if sizing is acceptable.
The drawing objects should fill the border but allow a margin (i.e. at least ½” gap between border and objects on all sides).
If border sizing is correct you are ready to plot, skip to Step 9. Otherwise continue.
Original Border
Plot Scale = 1:2
PSF = 1/2
Scaled Border 2X Original

25. Scaling – English Units - Machine
Step 7: If border sizing is unacceptable, the Plot Scale Factor must be recalculated:
Choose the next closest Plot Scale to 1:1 
A:B = 1:4 or A:B = 4:1
If the border must be increased:
Choose plot scale A:B = 1:4
The Plot Scale Factor = A / B = 1/4
If the border must be reduced:
Choose plot scale A:B = 4:1
The Plot Scale Factor = A / B = 4

26. Scaling – English Units - Machine
Step 8: Re-Scale the border using the inverse of the new Plot Scale Factor. Then test to see if sizing is acceptable.
Before re-scaling, the border must be returned to its original size:
Size
A-Size
B-Size
Sheet
8½ x 11
11 x 17
Border
7½ x 10
10 x 16
Use SCALE command or
Redraw original border rectangle
The drawing objects should fill the border but allow a margin (i.e. at least ½” gap between border and objects on all sides).
If border sizing is correct you are ready to plot, continue to Step 9. Otherwise, return to Step 7 and repeat the procedure again using the next closest plot scale to 1:1.

27. Scaling – English Units - Machine
Step 9: Plot the drawing.
The scaled border should be centered about your drawing.
Issue the PLOT command
Select a printer and the sheet size determined earlier.
What to Plot:
Choose Window, then select diagonal corners on your border rectangle.
Plot Offset:
Check  the Center the Plot box
Plot Scale:
Uncheck Fit to Paper box, then choose the Plot Scale (PS) determined earlier.
Plot Style :
Choose Monochrome
DO NOT click OK until results are verified with Preview button.
Retrieve your plot and Write the Plot Scale on the Sheet!!!

28. Scaling – English Units - Machine
Step 9: Plot the drawing.

29. Scaling CAD Drawings Essence of Scaling Procedure:
In essence, we are using the the border as a Scaling Gage to determine which standard plot scale makes our full size drawing fit onto the selected sheet size.
The original border size is designed to fit the physical paper sheet.
In the drawing, we scale the border with the SCALE command to fit the full size drawing using the inverse of a standard Plot Scale Factor.
If the border fits, then the drawing is plotted at the selected Plot Scale and the border is scaled back down by the Plot Scale Factor in the plot routine, returning to its original size.

30. Scaling CAD Drawings Essence of Scaling Procedure:
Original border (10x7½)
Designed to fit 11x8½ sheet
Scale border in drawing to fit full size objects  Use SCALE command at
1/Plot Scale Factor
Re-Scale border & object by plotting  Use PLOT command at Plot Scale Factor - returns border to original size

31. DEMO – English Plot Scale
Load file English Scale Demo.dwg.
Show use of DIST command.
Show methods for plotting to scale.

32. Exercise 4A:
Create and plot the following drawing to scale (see steps 1-9).
Step 1: Make the drawing using English units.
Step 2: Assume sheet will be A-size.
Step 3: Draw a border rectangle.
Step 4: Estimate the Plot Scale.
Step 5&6: Determine the Plot Scale Factor & scale the border.
Step 7&8: If necessary, repeatedly recalculate Plot Scale Factor & re-scale border.
Step 9: Plot your drawing to the appropriate scale and Write the Scale on Your Plot!
Step 10: Verify your plot size by measuring with a ruler.

33. End Lesson 13

34. Scaling CAD Drawings
General procedure for scaling a plot is the same regardless of drawing type, however there are slight differences for each of the following;
Machine drawings in English Units
Machine drawings in Metric Units
Architectural drawings
Next we look at the difference for a Machine drawing in Metric Units.

35. Scaling – Metric Units Step 1:
Start a new drawing using Start from Scratch with Metric units.
Create your drawing Full Size.

36. Scaling – Metric Units
Step 2: Determine sheet size to use. Varies according to;
 Assigment instructions  Physical size of part
 Amount of detail on part  Company standards
 Paper/plotter availability  Etc.
U.S. Standard (in)
International (mm)
BTC uses U.S. Standard lettered sheet sizes for all plots including metric.
Letter Sheet size size
A 8.5 x 11
B 11 x 17
C 17 x 22
D 22 x 34
E 34 x 44
Letter Sheet size size
A4 210 x 297
A3 297 x 420
A2 420 x 594
A1 594 x 841
A0 841 x 1189

37. Scaling – Metric Units
Step 3: In your drawing, generate a rectangular Border with dimensions equal to that of the Standard BTC title block border.
Since you are working in mm, the border size must be converted to mm (1 inch = 25.4 mm).
BTC uses ½” border margins, so Border dimensions will be 1” smaller than sheet size  But in mm!
Rectangle Border Dim:
Size
A-Size
8½” x 11”
B-Size
11” x 17”
English
Border
10” x 7.5”
16” x 10”
Metric
190.5 x 254
(mm)
254 x 406.4

38. Scaling – Metric Units
Step 4: Estimate the Plot Scale  same as for English drawing.
Step 5: Determine the Plot Scale Factor  same as for English drawing.
Step 6: Scale the border rectangle by the inverse of the Plot Scale Factor  same as for English drawing.
Step 7: If border scaling is incorrect, the Plot Scale Factor must be recalculated  same as for English drawing.
Step 8: Re-Scale the border using the inverse of the new Plot Scale Factor. Then test to see if sizing is acceptable.  same as for English drawing.

39. Scaling – Metric Units First: Select mm units Then: Set plot scale
Step 9: Plot the drawing same as for an English drawing except for the following:
The sheet size may default to a metric sheet, but select a U.S. standard Letter sheet size (i.e. A-size: Letter or B-size: 11 x 17).
BEFORE setting the plot scale, use the down arrow to select mm rather than inches. Then select the plot scale (i.e. 1:4).
The dialog box should then show 1 mm = 4 units which is correct!
First: Select mm units
Then: Set plot scale

40. DEMO – Metric Plot Scale
Load file Metric Scale Demo.dwg.
Show methods for plotting to scale.

41. Exercise 4B:
Create and plot the following drawing to scale (see steps 1-9).
Step 1: Make the drawing using Metric units.
Step 2: Assume sheet will be A-size.
Step 3: Draw a border rectangle.
Step 4: Estimate the Plot Scale.
Step 5&6: Determine the Plot Scale Factor & scale the border.
Step 7&8: If necessary, repeatedly recalculate Plot Scale Factor & re-scale border.
Step 9: Plot your drawing to the appropriate scale and Write the Scale on Your Plot!
Step 10: Verify your plot size by measuring with a ruler.

42. Scaling CAD Drawings
General procedure for scaling a plot is the same regardless of drawing type, however there are slight differences for each of the following;
Machine drawings in English Units
Machine drawings in Metric Units
Architectural drawings
Next we look at the difference for an Architectural Drawing.

43. Scaling – Architectural Units
Step 1:
Start new drawing using Start from Scratch with Imperial units.
Change your Units to Architectural format.
Create your drawing Full Size.

44. Scaling – Architectural Units
Step 2: Determine sheet size to use.
Same as for English Machine drawing.
Step 3: In your drawing, generate a rectangular Border with dimensions equal to that of the Standard BTC title block border.
Size
A-Size
B-Size
Sheet
8½ x 11
11 x 17
Border
7½ x 10
10 x 16

45. Scaling – English Units
Step 4: Estimate the Plot Scale.
Architectural drawings must conform to a standard Architectural scale.
Below are some standard Architectural plot scales.
Use DIST to measure the length & width of your drawing. Then select a scale you think will fit the objects within the border.
31’-0”
21’-0”

46. Scaling – English Units
Step 4 Continued: Estimate the Plot Scale.
If you forget the standard plot scales you can refer to the standard scales in the AutoCAD plot dialog box.
Guesstimate a plot scale that would reduce your model to fit within the full size border rectangle.

47. Scaling – English Units
Step 5: Determine the Plot Scale Factor.
Based on the Plot Scale you selected, calculate the Plot Scale Factor.
Plot Scale written A:B
Plot Scale Factor is A / B
Example:
Plot Scale is 1/64” = 1’-0”
Plot Scale Factor = (1/64) / 12
Plot Scale Factor = 1 / 768
Example:
Plot Scale is ¼” = 1’-0”
Plot Scale Factor = (¼)/12
Plot Scale Factor = 1/48

48. Scaling – Metric Units A” = 1’-0”
Step 6: Scale the border rectangle by the inverse of the Plot Scale Factor  same as for English Machine drawing.
Step 7: If border scaling is incorrect, the Plot Scale Factor must be recalculated  same as for English Machine drawing.
Step 8: Re-Scale the border using the inverse of the new Plot Scale Factor. Then test to see if sizing is acceptable  same as for English Machine drawing.
Step 9: Plot the drawing same as for English Machine drawing except choose the appropriate Architectural Scale in the form;
A” = 1’-0”

49. DEMO – Architectural Plot Scale
Load file Arch Scale Demo.dwg.
Show setting UNITS.
Show methods for plotting to scale.

50. Exercise 4B:
Create and plot the following drawing to scale (see steps 1-9).
Step 1: Make the drawing using Architectural units.
Step 2: Assume sheet will be A-size.
Step 3: Draw a border rectangle.
Step 4: Estimate the Plot Scale.
Step 5&6: Determine the Plot Scale Factor & scale the border.
Step 7&8: If necessary, repeatedly recalculate Plot Scale Factor & re-scale border.
Step 9: Plot your drawing to the appropriate scale and Write the Scale on Your Plot!
Step 10: Verify plot size by measuring with architectural scale.

51. End Lesson 14

52. Layers
What are Layers?
Layers are like overlaid sheets of transparent paper.
Each sheet may contain a different style of line with distinct color, line type, and thickness.
The sheets are perfectly aligned and each is given a name.
Individual layers can be turned on or off. When they are all on, the entire drawing is visible.

53. DEMO: Show General Use of Layers.
Show example using transparent overlay.
Open file Demo 1.dwg
Show example in AutoCAD

54. Layers
Why Use Layers?
Each layer can be assigned a different color, linetype, and line width  helps visibility and clarifies the drawing for you.
It is important to keep different line styles on different layers Alphabet of Lines (i.e. object, hidden lines, dimensions, etc).
Layers help organize the drawing into manageable pieces.
Layers can be turned on & off.
You can work on just the layer of interest.
Use as a selection tool for editing operations.
Plot only desired portions of drawing.
Layers can be locked to prevent accidental editing.

55. Layers
Creating Layers – several ways to create layers. Each brings up the Layers Properties Manager dialogue box.
Command: LAYER
DD Menu: Format > Layer…
Toolbar: Layers Toolbar

56. Layers
Layers Property Manager Dialogue Box.

57. Exercise 5:
Turn on the Layers Toolbar and embed below the Standard Toolbar.
Keep this in your menu…you will use it often.

58. Layers Things we need to learn about layers: Creating a new layer.
A set-up routine which creates a new layer and provides a name to it.
Assigning properties to a layer.
Line type
Color
Line weight
Make a layer current (active).
All drawn entities are drawn on the current active layer.
The lines comprising the object inherit the properties of the current layer.
Display of layers.

59. Layers Creating a new layer:
Use Layer Properties Manager – access from Layers Toolbar or LAYERS command.
Select New Layer button and provide a name.
Properties of new layer are inherited from the 0-layer or a highlighted layer.
Name easily edited.
New Layer Button
To Delete a layer

60. DEMO: Open a new file Show default layer (0) Open file Demo 1.dwg.
Show Creating a New Layer.
Show how new layer inherits properties from highlighted layer.
Show renaming layer.
Open file Demo 2.dwg.
Show default layers (0, DEFPOINTS)
Create standard layer names.

61. Layers Assigning Layer Properties: Color - use BTC std.
Line type - use BTC std.
Line weight - use BTC std.
Object Lines = 0.7”
Other Lines = 0.35”

62. DEMO: Show Assigning Layer Properties. Open file Demo 2.dwg. Linetype
Line Color
Line Weight

63. Layers Make Layer Current: Layer Properties Manager Button
Double-click name
Layer Control drop down box – select name

64. Layers Moving Objects Between Layers:
Objects can be moved to a different layer;
Select objects in the graphics window.
Select layer name in the Layer Control drop down.
Selected objects will be moved to layer name selected.
Select Layer Name
Objects moved to selected layer name

65. DEMO Show Moving Objects Between Layers. Open file Demo 2.dwg.
Current Layer:
Make layer current
Create objects on layer
Move objects to correct layers.

66. Layers Controlling Layer Display: Layer Properties Manager
Layer control Drop Down Box.
Plot/No Plot – use Layer Properties Manager
Freeze/Thaw
All VP 
Current VP Freeze/Thaw
On/Off 
Lock/Unlock

67. DEMO Making Layers Current and Display Options Open file Demo 2.dwg.
On/Off
Freeze/Thaw
Lock/Unlock
Plot/No Plot

68. Layers
Most companies use standard layers that all employees and vendors are required to adhere to.
This makes drawings interchangable and easy to decipher.
Likewise, BTC has its own standards to be used on ALL assignments as follows:

69. Exercise 6:
Set up the necessary layers for the drawing shown. Include line weights (thickness) according to alphabet of lines.
Red lines - Hidden lines mm.
White lines - Object (visible) lines – 0.7 mm.
Yellow lines – Centerlines – 0.35 mm.
Complete the drawing.
Don’t Draw Dimensions
Grid Spacing = 1.0

70. End Lesson 15

71. Setting Limits
Limits: - used to define the extent of the drawing area.
Command: LIMITS
Reset Model space limits:
Specify lower left corner or [ON/OFF] <0.0000,0.0000>:
Specify upper right corner < ,9.0000>:
The limits command is used in 2 ways;
It defines the extent of the grid pattern activated by the GRID command.
It determines the minimum area displayed by the ZOOM command with the ALL option.

72. Setting Limits Effective use of Limits:
If you draw objects larger than your Limits, the zoom function is likely to freeze-up. You can correct this;
Reset your limits to a value larger than your largest expected object.
Issue ZOOM > ALL, this will zoom to your Limits or the current extent of your drawing (whichever is larger).
Limits can be reset at any time. If your drawing size increases, increase your limits to accommodate the new size.

73. Setting Limits
Once your limits are set, the GRID command can be used to view the limits. Grid can be activated in several ways;
Command: GRID
Use the [F7] key as a Grid Toggle
Use the [GRID] Toggle button in the status bar menu (bottom of screen).
Once the grid is activated, you should ZOOM > ALL to be sure the entire limits of the screen are displayed.

74. DEMO – GRID & SNAP DEMO – Limits DEMO – Grid Spacing
DD Menu: Tools > Drafting Settings
Command: GRID
[GRID] toggle
[F7] key
Right Click [GRID] Settings…
DEMO – Snap
Command: SNAP
[SNAP] toggle
[F9] key
Right Click [SNAP] Settings…

75. Exercise 7:
Draw the following using ONLY snap and grid (no direct coordinate inputs allowed).
If you finish early, create an OBJECT layer & CENTERLINE layer. Move all lines to the Object layer, and then create centerlines on the CENTER layer.
Origin (0,0)

76. DEMO – ORTHO MODE
DEMO – Ortho Mode
Command: ORTHO
[ORTHO]
[F8] key

77. Exercise 8:
Set your Units and Limits. Then draw the following using Ortho Mode and direct distance input. Wall thickness = 1’
Origin (0,0)

78. Object Snap
Object Snap – a method for “snapping” to points on previously defined geometry.
3 methods to activate Object Snap “on the fly”.
Select from Object Snap Toolbar.
Type in Object Snap name abbreviation.
Hold [Shift] or [Ctrl] and right click mouse for shortcut.
Object Snap Tool Bar
Hurray! Finally something Really useful!

79. Exercise 9:
Turn on the Object Snap Toolbar and embed it in a convenient place in the menu.
Keep this in your menu…you will use it often.

80. Object Snap
Snap to ENDpoint – snaps to nearest endpoint of a line or arc.
Tip: Use Tool Tips to determine name of each icon.

81. Object Snap
Snap to NEArest – snaps to a point on an object (line, circle, etc.) closest to the cursor crosshair.

82. End Lesson 16

83. Object Snap
Snap to MIDpoint – snaps to midpoint of a line or arc.

84. Object Snap
Snap to Mid Between 2 Points (MTP) – Snaps to midpoint between 2 selected points.
Not available on toolbar.
Requires multiple snap selection to select points to snap between.
2) End Point Snap
3) End Point Snap
1) Choose Mid Between 2 Points

85. Exercise 10:
Create a new layer using default linetype and color yellow.
Create the yellow objects approximately as shown.
Create a new layer using default linetype and color magenta.
Use Osnap to create the magenta lines.
Move the yellow line such that its midpoint is located half way between the arc endpoints (Hint: use Mid Between 2 Points).
END
MID
MID
END
END
NEA
MID
NEA

86. Object Snap
Snap to TANgent – snaps to tangent of circle, arc or ellipse.

87. Object Snap
Snap to CENter – snaps to center of circle, arc or ellipse.

88. Object Snap
Snap to INTersection – snaps to intersection or extended intersection of 2 objects.

89. Object Snap Recommend you do not use this option!
Snap to APPArent Intersection – used for 3D applications - snaps to the apparent extended intersection point of 2 selected entities which don’t actually intersect (different Z-coordinates).
Recommend you do not use this option!

90. Object Snap
Snap to QUAdrant – snaps to quadrant point of circle, arc, or ellipse.

91. Object Snap
Snap to PERpendicular – snaps normal to a line or radially to an arc or circle.

92. Exercise 11:
Draw the two circles first, the remaining white objects next, and the blue lines last. Use the Object Snaps indicated.
Grid spacing = 1”.
arc radius

93. Object Snap
Snap to NODe – snaps to a Point object.

94. Object Snap
Snap to INSertion – snaps to the insertion point of a Block, Text, Shape, or Attribute.

95. Object Snap
Snap FROm – locates a point offset from a selected point. Offset must be specified by keyboard entry.

96. Object Snap
Snap PARallel – assures line is drawn parallel to selected object. Briefly pause curser on line, then move cursor into parallel position.

97. End Lesson 17

98. Object Snap
Snap EXTension – locates a point on the extension path of a line or arc. Briefly pause curser on end of object to extend then move cursor into aligned position.
Acquire multiple extensions to snap to the intersection of 2 extension paths.

99. Object Snap
Snap Temporary TRACKing – locates a point by temporary perpendicular tracking from a selected point. The X and Y coordinates from separate points can be acquired by successive selection of Temporary Tracking.

100. Exercise 12:
Create the lines shown using keyboard entry and the coordinates provided.
(0,0)
(2,0)
(0,4)
(2,5)
(4,5)
(2,3)
(4,3)
(6,4)
(6,0)

101. Exercise 12:
Complete the green lines using ONLY Osnap. No keyboard entry, no Ortho, no nothing else! (Hint: temporary tracking is required).
Mid
per

102. Running Object Snap
Running Object Snap – maintains activation of selected Osnaps.
Command: OSNAP
DDMenu: Tools > Drafting Setting…
Right click on [OSNAP]
Just what you’ve been waiting for!!!

103. Running Object Snap Subtleties of Running Object Snap:
Toggled on/off by [F3] or [OSNAP].
An Osnap selected from the toolbar, shortcut menu, or typed abbreviation will over-ride all running Osnap settings.
[Tab] key allows cycling through running Osnap selections if more than one is activating.
Zooming will “refresh” all osnap selections and tracking patterns.
Selecting too many Osnaps can cause confusion. Be selective and avoid Apparent Intersection.

104. Auto-Tracking Q: What is Auto-Tracking?
A: Method for locating points using temporarily displayed alignment paths based on set angles or positional relationship with selected objects.
Two Types:
Polar Tracking – displays temporary alignment paths along angles that you specify. Angles are referenced from x-axis or from orientation of line (i.e. if an inclined line is selected by object snap, the angles can be referenced with respect to the inclined line).
Object Snap Tracking – displays temporary alignment paths along  axes from selected points. Points are “acquired” by passing the cursor over the snap point, or removed by passing over the snap point a second time.

105. Auto-Tracking Polar Tracking – Toggled on/off by [F10] or [POLAR].
Polar angle for alignment paths are specified in Drafting Settings dialogue box.
DD Menu: Tools > Drafting Settings…
Ortho Mode will be disabled when using Polar Snap Tracking and vice versa.

106. DEMO TRACKING: Open file Track_Demo.dwg Show Polar Tracking.
Show use of Polar Intersection.
Show Additional Angles.

107. Auto-Tracking
Object Snap Tracking – Toggled on/off by [F11] or [OTRACK].
Alignment paths are acquired by “brushing” points on objects using object snap (object snap must be enabled to select the points).
Points are selected by passing cursor over them without clicking the mouse.
Alignment paths are orthogonal (parallel to X & Y axes).
Successive points may be acquired to obtain multiple alignment paths.
Points may be unselected by passing mouse over point again.

108. DEMO TRACKING: Open file Track_Demo.dwg Show Object Snap Tracking.
Method for Multi-view drawing.

109. Exercise 12:
Draw the following objects using ONLY mouse input and direct distance input (coordinate determined by cursor direction from last point and keyboard distance value ). Use Object Snap Tracking, and Polar Tracking to maintain point alignment.
30

110. End Lesson 18

111. Review of Function Keys
[F1] - Help
[F2] – Graphics Screen/Text Window
[F3] – Running Osnap
[F4]
[F5]
[F6]
[F7] – Grid
[F8] – Ortho
[F9] – Snap
[F10] – Polar Tracking
[F11] – Object Snap Tracking
Review of Function Keys
Keyboard Template

112. Linetype Scaling A B Linetype Scaling: Command: LTSCALE
Scales all linetypes globally (Default = 1.0).
Scales each segment in the linetype by the ltscale factor.
Overall line length doesn’t change.
Example: With LTSCALE = 0.5, Centerline shown in A will display as shown in B.
Centerline ________ __ ________ __ ________
LTSCALE = 1 A
Centerline ___ _ ____ _ ____ _ ____ _ ____ _ ___ B
LTSCALE = 0.5

113. DEMO LTSCALE:
Open file LTSCALE_Demo.dwg
Show use of LTSCALE

114. Linetype Scaling Linetype Scaling: Command: CELTSCALE
Controls current linetype scaling (Default = 1.0). After CELTSCALE is set, all new lines will be scaled by this factor.
Lines affected by CELTSCALE are also affected by LTSCALE. The two are multiplied to give final linetype scale.

115. DEMO LTSCALE:
Open file LTSCALE_Demo.dwg
Show use of CELTSCALE

116. Linetype Scaling Linetype Scaling: Command: CELTSCALE
Value of CELTSCALE for individual objects may be altered after line creation using the PROPERTIES command.
PROPERTIES is accessed thru the shortcut menu.
This variable is changed by the CELTSCALE command

117. DEMO LTSCALE: Open file LTSCALE_Demo.dwg
Show use of PROPERTIES for setting CELTSCALE.

118. Linetype Scaling
As you know from Drafting, each linetype consists of patterned segments of defined length.
To maintain correct segment lengths on printed output, the linetypes should be scaled if the plot requires scaling.
If the plot scale is 1:4 (scale factor of ¼), the linetypes should be scaled by the inverse of the scale factor (or 4).
A larger linetype scale factor increases segment length. A smaller linetype scale factor reduces segment length.
Rule of thumb: Linetype Scale Factor = 1 / (plot scale factor)

119. Linetype Scaling Example:
Required space for full size drawing is 5 x 3.75.
Decide on A-size sheet (11x8.5) using 2:1 scale.
Prior to plotting, set LTSCALE to 0.5 to get correct plotted line segments.

120. DEMO LTSCALE: Open file LTSCALE_Demo.dwg
Show use of LTSCALE, CELTSCALE, and PROPERTIES for setting linetype scale for different size drawings.

121. Linetype Scaling Alternate Linetypes:
LTSCALE acts globally and affects all linetypes.
What if you want short lines to have short segment lengths and long lines to have long segment lengths?
Three ways to get this:
Use the CELTSCALE to control linetype scaling during line creation.
Use PROPERTIES to change CELTSCALE variable for existing objects.
Use Alternate Linetypes having similar patterns but different segment lengths (i.e. Center, Center2, Centerx2)
CELTSCALE command changes this variable.

122. Linetype Scaling Example: Alternate Linetypes Original Linetype
Use this for short lines.
Use this for long lines.
CENTER
CENTERX2
Short Segments
Standard
Long Segments
CENTER2
CENTER
CENTERX2
HIDDEN2
HIDDEN
HIDDENX2
PHANTOM2
PHANTOM
PHANTOMX2

123. DEMO LTSCALE: Open file LTSCALE_Demo.dwg
Show use of Alternate LineTypes

124. Chapter 4 – The End!

125. RETIRED MATERIAL

126. Units Format
Sign of Angle: - by default, AutoCAD assumes a Counterclockwise rotation is Positive. To reverse this, check the Clockwise box. ?
Base Angle: - assumed to be from +X-axis. Use Direction to change this (see next slide).

127. Units Format
Base Angle: - the Base angle reference is designated according to compass headings. The default setting is East which assumes measurement from pos. X-axis. This can be changed using Direction Control Dialogue Box. Y X

128. Exercise 1: Open a new drawing file with English (Imperial) Units.
Set the Units to Decimal with a precision of 0.0.
Set the Angle to decimal with a precision of 0.
Set the angle to CLOCKWISE and set the Base angle direction to North.
Create the drawing shown using Polar Coordinates and Keyboard entry ONLY!
When finished, be sure to return the angle settings back to the defaults:
30º
Start Point (0,0)
Base Angle = East
+ Angle = Counter Clockwise

129. Setting Limits Limits: - the user defined extent for the drawing area.
The limits command is used in several ways;
It defines the extent of the grid pattern activated by the GRID command.
It determines the minimum area displayed by the ZOOM, ALL command.
It can also be used as the defined plot region in the PLOT command.
Additional functionality for Limits;
If Limits is set to ON, AutoCAD won’t allow a coordinate to be specified outside the defined limits.

130. Setting Limits Limits:
In AutoCAD, like most CAD programs, objects are drawn full size.
Scaling doesn’t occur until you are ready to print on to a sheet of paper.
Limits should be set to accommodate the full size drawing.
Default limits in AutoCAD are;
Imperial: x 9.0 inches
Metric: 420 x 297 mm

131. Setting Limits Setting Limits: Command: LIMITS
DD Menu: Format > Drawing Limits
Reset Model space limits:
Specify lower left corner or [ON/OFF] <0.0000,0.0000>:
Specify upper right corner < ,9.0000>:

132. Setting Limits
Once your limits are set, the GRID command can be used to view the limits. Grid can be activated in several ways;
Command: GRID
Use the [F7] key as a Grid Toggle
Use the [GRID] Toggle button in the status bar menu (bottom of screen).
Once the grid is activated, you should ZOOM > ALL to be sure the entire limits of the screen are displayed.
*Important – the end grid points will not necessarily align with the boundary of your limits definition. Grid points always fall at fixed increments that you define and always lie within, or possibly on, the limits boundary.

133. Setting Limits Effective use of Limits:
If you draw objects larger than your Limits, the zoom function is likely to freeze-up. You can correct this;
Reset your limits to a value larger than your largest object.
Issue ZOOM > ALL, this will zoom to your Limits or the current extent of your drawing (whichever is larger).
Toggle on Grid to verify Limits (reset grid spacing if necessary).
Limits can be reset at any time. If your drawing size increases, increase your limits to accommodate the new size.

134. DEMO Show use of LIMITS command. Open new drawing file.
Command: LIMITS
DDMenu: Format > Drawing Limits
Show activation of grid.
Command: GRID
[F7] key
[GRID] toggle button
Grid too dense
Show Zoom, ALL
Turn LIMITS ON

135. Exercise 3:
Open a New file using Start from Scratch with Imperial (English) units.
Use the LIMITS command to check your current limits setting.
Activate GRID to view your current limits.
Draw a line from (0, 0) to (450, 250), then use the scroll wheel on your mouse to try and zoom way out…Lock-Up!
Turn off the grid, then use ZOOM > ALL to view the entire line.
Reset your limits to 500 x 300.
Turn the grid back on…Too Dense! Change the grid spacing from 0.5 to 10.0.
Delete the line and reset your limits to 12 x 9. Then ZOOM > ALL.
Finally, reset the grid spacing back to a reasonable value.

136. Setting Limits
Effective use of Limits: - Before attempting any drawing, the Limits of the drawing should be calculated.
This is where you get to use your sketching skills.
Step 1: Identify the size extents of the object you are going to draw (height, width, depth)
Step 2: Sketch a layout of the various views to be included and identify the overall width and height required. This should include space between views, room for dimensions, and edge margins.
Step 3: Knowing the space (width and height) required, determine what size paper sheet will be used to print (A, B, etc). Obviously scaling may be required for larger or smaller objects. Note the scale factor required.

137. Setting Limits
Step 4: Knowing the paper size, find the printable area of the sheet (use Printable Area under PLOT command)
Step 5: If the drawing will be full scale (1:1) the limits will equal the Printable Area. If the drawing will be scaled to plot, divide the length and width of the printable area by the scale factor i.e. if scale factor is ½ (1:2), then divide by ½ (or multiply by 2). These are the limits.
Step 6: Input the limits for the drawing. Then make a rectangle corresponding to the limits. This is the printable area which will be plotted at the appropriate scale.
Step 7: Create your drawing using the rectangle as a guideline for the drawing boundaries.
Step 8: Plot your drawing to the appropriate scale.

138. Setting Limits Review – Standard Sheet Sizes U.S. Standard
International Standard
Letter Sheet size size
A 8.5 x 11
B 11 x 17
C 17 x 22
D 22 x 34
E 34 x 44
Letter Sheet size size
A4 210 x 297
A3 297 x 420
A2 420 x 594
A1 594 x 841
A0 841 x 1189

139. Setting Limits Review – Standard Scales
Example: if the scale is ¼” = 1’-0
¼” = 12”
¼ : 12
1/48 : 1
The scale factor is 1/48
Example: if the scale is 1 : 8
1/8 : 8/8
1/8 : 1
The scale factor is 1/8
*Note: ¼”=1’-0 should be shown on drawing

140. Scaling – English Units
Method for Scaling:
The next 2 steps require you to resize and move the border so it fits around the drawing objects  SCALE command.
Command: SCALE
Select objects: select border rectangle
Specify base point: select any point near rect. corner
Specify scale factor or [Reference]: input BSF
Border small compared to object  scale up border.
Border Scale Factor (BSF) > 1
Border large compared to object  scale down border.
Border Scale Factor (BSF) < 1
Never scale the drawing objects!

141. Scaling – English Units
Method for Scaling:
The next 2 steps require you to resize and move the standard border so it fits around the drawing objects.
Use the SCALE command to resize the border and MOVE command to center the border around the drawing objects.
We will refer to the border size increase or decrease as the Border Scale Factor (BSF).
Border small compared to object  scale up border.
Border Scale Factor (BSF) > 1
Border large compared to object  scale down border.
Border Scale Factor (BSF) < 1
Never scale the drawing objects!

142. Scaling – English Units
Review:
Standard Plot Scales (English Machine Drawings)
Scale Factors
Plot Scale written A:B
Plot Scale Factor is A / B
Example:
Plot Scale is 1:8
Plot Scale Factor = 1/8
Plot Scale is 4:1
Plot Scale Factor = 4

143. Scaling – English Units
Step 4: Determine the Border Scale Factor (BSF).
The Border Scale Factor (BSF) must be calculated based on Standard Plot Scales. Refer to the standard scales in the AutoCAD plot dialog box.
Choose a plot scale that would reduce/enlarge your model so it fits within the full size border rectangle. Or start by choosing a plot scale closest to 1:1, either A:B = 1:2 or A:B = 2:1

144. Scaling – English Units
Step 4: Determine the Border Scale Factor (BSF).
The Border Scale Factor (BSF) is the inverse of the Plot Scale Factor (PSF)
If the border must be increased:
Choose Plot Scale A:B = 1:2
The Plot Scale Factor (PSF) = A / B = 1/2
The Border Scale Factor (BSF) = B / A = 2
If the border must be reduced:
Choose Plot Scale A:B = 2:1
The Plot Scale Factor (PSF) = A / B = 2
The Border Scale Factor (BSF) = B / A = 1/2

145. Scaling – English Units
Step 5: Scale the border using the calculated Border Scale Factor (BSF). Then test to see if sizing is acceptable.
The drawing objects should fill the border but allow a margin (i.e. at least ½” gap between border and objects on all sides).
If border sizing is correct you are ready to plot, skip to Step 8. Otherwise continue.
Original Border
Plot Scale = 1:2
PSF = 1/2
BSF = 2
Scaled Border

146. Scaling – English Units
Step 6: If border scaling is incorrect, the Border Scale Factor (BSF) must be recalculated:
Choose the next closest Plot Scale to 1:1 
A:B = 1:4 or A:B = 4:1
If the border must be increased:
Choose plot scale A:B = 1:4
The Plot Scale Factor (PSF) = A / B = 1/4
The Border Scale Factor (BSF) = B / A = 4
If the border must be reduced:
Choose plot scale A:B = 4:1
The Plot Scale Factor (PSF) = A / B = 4
The Border Scale Factor (BSF) = B / A = 1/4

147. Scaling – English Units
Step 7: Re-Scale the border using the new Border Scale Factor (BSF). Then test to see if sizing is acceptable.
Before re-scaling, the border must be returned to its original size:
Size
A-Size
B-Size
Sheet
8½ x 11
11 x 17
Border
7½ x 10
10 x 16
Use SCALE command or
Redraw original border rectangle
The drawing objects should fill the border but allow a margin (i.e. at least ½” gap between border and objects on all sides).
If border sizing is correct you are ready to plot, continue to Step 8. Otherwise, return to Step 6 and repeat the procedure again using the next closest plot scale to 1:1.

148. DEMO - Limits Load file Limits Demo.dwg. Show use of DIST command.
Show method for finding printable area.
Show method for defining limits.
Show methods for plotting to scale.

149. Setting Limits Slow Motion Replay:
Step 1: Identify the size extents of the object you are going to draw (height, width, depth)

150. Setting Limits
Step 2: Sketch a layout of the various views to be included and identify the overall width and height required.
This should include space between views, room for dimensions, and edge margins.
Size Requirements:
Width = 20.0”
Height = 14.0”

151. Setting Limits
Step 3: Knowing the size (width and height) required, determine what size paper sheet will be used to print (A, B, etc). Obviously scaling may be required for larger or smaller objects. Note the scale factor required.
Requred size for full size object = 20” x 14”
Sheet size “A” = 11” x 8.5” Try plot scale = 1:2
Plotted drawing will then require 10”x7”:
½ x 20” = 10”
½ x 14” = 7”

152. Setting Limits
Step 4: Knowing the paper size, find the printable area on the sheet (use Printable Area under PLOT command)
10.38 x 7.94 printable area.

153. Setting Limits
Step 5: If the drawing will be full scale (1:1) the limits equal the printable area. If the drawing will be scaled to plot, divide the length and width of the printable area by the scale factor i.e. if scale factor is ½ (1:2), then divide by ½ (or multiply by 2). These are the limits
Scale: 1: Scale factor = ½
Required space for full size drawing = 20 x14
Sheet Size = “A” = 8.5 x 11
Printable Area = x 7.94
X - Limit = x 2 = 20.96
Y - Limit = 7.94 x 2 = 15.88
*NOTE – The book suggests limits based on paper sizes. These are not accurate since not based on Printable Area.

154. Setting Limits
Step 6: Input the limits for the drawing. Then make a rectangle corresponding to the limits. This is the printable area which will be plotted at the appropriate scale.
Scale: 1:2
full size drawing = 20 x14
Sheet Size = “A” = 8.5 x 11
Printable Area = x 7.94
X - Limit = x 2 = 20.96
Y - Limit = 7.94 x 2 = 15.88

155. Setting Limits
Step 7: Create your drawing using the rectangle as a guideline for the drawing boundaries.
Limits Rectangle
Object Boundary
with Margins

156. Setting Limits
Step 8: Plot your drawing to the appropriate scale. You can use Limits for the Plot Area or use Window and select the corners of the rectangle representing the Limits.

157. Exercise 3:
Perform the setup required to make the following drawing (see steps 1-8).
Assume single view will be used, only draw boundary walls (31”x21”) i.e. neglect the interior walls, etc.
Assume sheet will be A-size.
Step 1: Identify drawing view size (height, width).
Step 2: Identify the overall width and height required (include 1” margins).
Step 3: Determine paper size (A-size), and scale (you can figure this out).
Step 4: Find printable area of sheet.
Step 5: Calculate and set the limits from printable area and scale.
Step 6: Make a rectangle corresponding to the limits.
Step 7: Create your drawing.
Step 8: Plot your drawing to the appropriate scale.

158. Exercise 3: Solution
Step 1: Identify view size (height, width). (31” x 21”)
Step 2: Identify the overall width and height required (include 1” margins).
(33” x 23”)
Step 3: Determine paper size, and scale. 33”/4 = 8.25” ”/4 = 5.75” OK
A-Size sheet = 11” x 8.5” Scale = 1:4
Step 4: Find printable area of sheet.
10.38” x 7.94”
Step 5: Calculate the limits from printable area and scale.
10.38”x4 = 41.52” ”x4 = 31.76”
Step 6: Make a rectangle corresponding to the limits.
Step 7: Create your drawing.
Step 8: Plot your drawing to the appropriate scale.
Limits rectangle (41.52 x 31.76)

159. Exercise 4:
Consider the following part. You are to make a multiview drawing (3 views – Front, Top, Right Side) of the part using the correct use of Units and Limits. The drawing should be plotted on an A-size sheet. Allow at least 1” margins and 2” between views.

160. Exercise 4: 3 views – Front, Top, Right Side A-Size sheet
Step 1: Identify the size of the object (height, width, depth)
Step 2: Sketch a layout of the views to be included and identify the overall width and height required.
Step 3: Determine paper size, and scale.
Step 4: Find printable area of sheet.
Step 5: Calculate the limits from printable area and scale.
Step 6: Make a rectangle corresponding to the limits.
Step 7: Create your drawing.
Step 8: Plot your drawing to the appropriate scale.