When you have completed this module, you will be able to:
1. Describe the AutoCAD features grid and snap.2. Describe and apply the commands GRID, SNAP, SNAPBASE, and ORTHO to draw
three views of three dimensional objects.
Using Grids and SnapGrids are a series of pixels that overlay your drawing in a rectangular shape similar tooverlaying a paper drawing with grid paper. Grids do not plot and are not part of the database.They are simply a drawing aid. You can change the grid's density or enable or disable it'sdisplay anytime you wish. The horizontal and vertical spacing between the grid pixels can bedifferent but are equal by default. You can toggle the grid display with the F7 key or with thestatus bar.The size of the rectangle the grid fills is always the size of the drawing limits. If you want thegrid on your drawing to appear larger of smaller, change the size of the limits.The snap feature works in conjunction with grids. If snap is enabled, the graphic cursor snapsto grid pixels just like object snap modes. The grid display and the snap density do not have tobe the same density. Therefore, you could snap to pixels between the displayed grid pixels.The snap can be toggled using the F9 key or with the status bar.
AutoCAD Command: GRIDThe GRID command is used to overlay the drawing limits with a series of pixels in either an equalor unequal horizontal and vertical spacing.
Shortcut: F7
AutoCAD Command: SNAPThe SNAP command is used to enable the snap feature plus it controls the angle, type, andfunction of the graphic cursor.
If you find your cursor jumping around your screen and hard to control,check the status bar. Some commands will toggle the snap mode withoutyou knowing it.
Snap is toggled ON here.
Remember you can toggle the snap with F9 or by clicking the status bar.
Snap is toggled OFF here.
System Variable: SNAPBASEThe SNAPBASE command is used to specify the XY coordinates location for the origin of the gridand snap pixels. This coordinate location is also used by hatch patterns as their origin as you willsee in Module 29.
Ortho ModeAutoCAD has a feature called ortho mode. When enabled, ortho mode locks the graphic cursorso it can only move vertical or horizontal. This can affect most commands and some entereddistances. This is a very important feature and used for many applications as you will see asyou as you work your way through the modules. You can toggle the ortho mode with the F8key or with the status bar.
AutoCAD Command: ORTHOThe ORTHO command is used to lock the graphic cursor to allow it to only move horizontal orvertical. When enabled, it applies to most commands.
Shortcut: F8
Whenever possible, use the keyboard function keys to toggle featuresrather then using the status bar or commands. It is a much faster way totoggle them plus it will save the wear and tear on your mouse arm. Thefunction keys that you have learned to this point in the modules are:
F1 - HelpF2 - Text WindowF3 - AutosnapF6 - Coordinate Location Display (2000-2006)F7 - GridF8 - OrthoF9 - Snap
The Drafting Settings dialogue box can be used to set or check the grid,
18 - 3
snap and snapbase settings for your drawing. To access it, use either theTools pull-down menu or right-click any item in the status bar (exceptModel) and click Settings as shown below.
Using the GRID and SNAP CommandsStep 1 Start a new drawing using the template Module Template A.
Step 2 Save and namethe drawing AutoCAD 2DWorkalong 18-1.
Step 3 Open the DraftingSetting dialogue box. (SeeUser Tip above). In theSnap and Grid tab, set theX and Y snap and gridspacings to 0.5 as shown inFigure Step 3. Check theother settings and changethem if necessary to matchthe figure.
Step 4 Press F7. This will enable the grid display andyour drawing should appear similar to Figure Step 4.
(Note how the grid does not fill the drawing. The reason forthis is the grid will always fill the limits of the drawing.)
Step 5 Change the limits of the drawing by enteringthe following command.Command: LIMITSReset Model space limits:Specify lower left corner or [ON/OFF] <0.0000,0.0000>:
(Leave the lower left corner at 0,0.)Specify upper right corner <12.0000,9.0000>: 8.5,11
(Set the upper right corner to X8.5,Y11.)Command:
(For more information on the LIMITS command, read Module 9. Thegrid will now fill the drawing as shown in Figure Step 5.
Step 6 Press F9. This enablessnap mode. Move your cursoraround the drawing and notice howit will jump from grid to grid. Whensnap is enabled, you will only beable to draw from snap point to snap
Figure Step 4
Figure Step 5
Figure Step 7
..continued on page 18-5
point. Currently the snap spacing and the grid spacing are bothset to 0.5 units.
Step 7 Using the LINE command, draw a 4 unit square asshown in Figure Step 7. Since the grid and snap are set at 0.5units, you will have to count 8 spaces between grid points bothhorizontally and vertically.
The grid will fill the limits of thedrawing. If you want to change thesize and/or area that the grid coverson the drawing, simply change thelimits. You can do that using theLIMITS command. See Module 9.
Step 8 Open the DraftingSetting dialogue box.Change the setting of thesnap spacing to 0.25 forboth the X and Y as shownin Figure Step 8. Click OKto close the dialogue box.
Figure Step 8Step 9 Using the LINEcommand, draw another square inside the first one.On this one, snap to the snap points between the gridrather then the grid points as you did before. SeeFigure Step 9.Step 10 Enter the commands shown below to changethe location of the snapbase.Command: SNAPBASEEnter new value for SNAPBASE <0.0000,0.0000>: (end) P1
(Snap to the left end of the line along the bottom of thetitleblock as shown in figure 10A.)
Command: REGEN(Regen the drawing)
Regenerating model.Command:
Note how the grid has changed the location of thepixels. They now originate from the end of the bottom
18 - 5
line of the titleblock which is the current snapbase.See Figure Step 10B.
Figure Step 10A
Step 11 Press F7 and F9 to disable both the gridand snap functions.
Step 1 Start a new drawing using the template Module Template A3.
Step 2 Save and name the drawing AutoCAD 2D Workalong 18-2.
Step 3 Figure Step 3A is a 3D solid model of an object and Figure Step 3B is a 3Dwireframe model of the same object. In thisworkalong, you will be drawing the front, top and rightside multiviews of this object. Figure Step 3C showsthe 3 multiviews you will be drawing using ortho modeto assist you.
Using Ortho Mode - ContinuedStep 4 Create layers Object,Hidden and Construction. Note thecolor and linetype assigned toeach layer as shown in Figure Step4.
Author's Comments:Figure Step 4
When ortho mode is enabled, you
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can shortcut coordinate input. You are only required to enter the distance along the axis.This will save you time and save you some keyboard input.
Step 5 Enable ortho mode by pressing F8. On layer Object, draw the front view byentering the LINE command shown below.Command: LSpecify first point: 100,100
(Move the cursor in the positive X direction.)Specify next point or [Undo]: 40
(Note how you only have to enter the X distance. As long as orthomode is enabled, you are not required to enter the @.)(See Figure Step 5A)
Figure Step 5A
(Move the cursor in the positive Ydirection.)
Specify next point or [Undo]: 20(See Figure Step 5B)
Figure Step 5B
(Move the cursor in the positive X direction.)Specify next point or [Undo]: 20
(See Figure Step 5C)
Figure Step 5D
(Move the cursor in the negativeY direction.)
Specify next point or [Undo]: 20(See Figure Step 5D)
Figure Step 5C
(Move the cursor in the positive X direction.)Specify next point or [Undo]: 40
Using Ortho Mode - ContinuedSpecify next point or [Undo]: @-25,50
(The cursor position is not important when you enter exactcoordinates. Ortho mode will be ignored when both coordinatesare entered. See Figure Step 5F)
(Move the cursor in the negativeX direction.)
Specify next point or [Undo]: 50(See Figure Step 5G)
Specify next point or[Close/Undo]: CSpecify next point or [Close/Undo]:Command:
Figure Step 5G
The contour of the front view is completeas shown in Figure Step 5H
Step 6A Create the top and right sideviews using the front view you just drew.With ortho mode and osnap modeenabled, draw on layer Construction.Using the LINE command, draw avertical line by snapping the first point to
Figure Step 5F
the end of the bottom line as shown infigure Step 6A.
Figure Step 6A
Figure Step 5H
Figure Step 6B
Step 6B Move the cursor in the positive Y direction and with ortho mode enabled, this willdraw a vertical line. Take a guess at the length of the line. See Figure Step 6B.
Step 6C Repeat the same thing fivemore times to draw a vertical line fromeach endpoint on the front view. SeeFigure Step 6C
Figure Step 6C
Step 6D Draw horizontal lines from
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Figure Step 6D
Step 7A Draw a 45 degree line starting fromthe intersection of the right line and the topline of the front view as shown in Figure Step7A. The line should be a least 200 units long.
Figure Step 7B
...continued on page 18-10
the three endpoints on the front view.Take a guess at the length of the lines.
Figure Step 7A
Step 7B Using ortho mode, draw ahorizontal line as shown in Figure Step 7B.The distance and length of line is notimportant. Try to match the figure as closeas you can using Figure Step 7B as aguide.
Step 7C Using the OFFSET command, offset theline you drew in Step 7B, 50 units upwards asshown in Figure Step 7C.
Figure Step 7C
Figure Step 7D
Step 7D Offset each line in the top view, 17.5 unitstoward the center of the view as shown in FigureStep 7D.
Step 7E From the intersection of the lines inthe top view and where they cross the 45degree line, use ortho mode to draw verticallines as shown in figure 7E.
Figure Step 7E
Figure Step 8A
Step 8A Trim the lines in the top view and rightside view to match the views in Figure Step 8A.
Step 8B Offset the top line of the right side view,10 units down as shown in figure Step 8B.
When you are only given the location for theendpoints and midpoint of an arc and not thecenter or the radius, you can use the 3 pointarc option.
Draw the construction lines as given by thedimensions.
Using the ARC command:
Command: ARCSpecify start point of arc or [Center]: (end) P1Specify second point of arc or [Center/End]: (mid) P2Specify end point of arc: (end) P3Command:
The Key Principles in Module 181. The grid always fills the rectangle or square shape defined by the limits of the drawing.
2. Ortho mode locks the graphic cursor so it can only move along the X and Y axis. Anexact XY coordinate will override ortho mode.
3. The grid display and the snap density do not have to be set to the same size.
AutoCAD 2D Lab 18-1 Module Template C Inches N/A N/A
Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.
Layering Scheme
Objects on Layer Name Color Linetype LineweightConstruction Objects
Object Lines
Hidden LinesInstructions:
Construction
Object
Hidden
253
Red
Blue
Continuous
Continuous
Hidden
N/A
N/A
N/A
1. Setup the layers using the Layering Scheme shown above.2. Draw all construction objects on layer Construction.3. Draw the top, front and right side views of the model below.4. Add the hidden lines where required..5. Space the views 2 units apart to enable you to use the key to
check your drawing.6. Check your drawing with the key.7. Turn layer Key off and freeze layer Construction.8. Save and close the drawing.
Construction TechniqueThe following steps are the construction technique suggested by the author to help you learnhow to construct objects using AutoCAD. It is only the suggested method and if you cancomplete the drawing accurately using a different construct technique, that is what is important.You may want to compare your construction technique with the authors.
Construction HintsDo your best to complete the lab exercise drawing without using the following hint(s). If you getstuck and can't complete it on your own, use the following hint(s) to help you.
Hint 1
Draw the arc in the frontview using the User Tip onpage 18-12.
AutoCAD 2D Lab 18-2 Module Template C Inches N/A N/A
Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.
Layering Scheme
Objects on Layer Name Color Linetype LineweightConstruction Objects
Object Lines
Hidden LinesInstructions:
Construction
Object
Hidden
253
Red
Blue
Continuous
Continuous
Hidden
N/A
N/A
N/A
1. Setup the layers using the Layering Scheme shown above.2. Draw all construction objects on layer Construction.3. Draw the top, front and right side views of the model below.4. Add the hidden lines where required..5. Space the views 2 units apart to enable you to use the key to
check your drawing.6. Check your drawing with the key.7. Turn layer Key off and freeze layer Construction.8. Save and close the drawing.
Construction HintsDo your best to complete the lab exercise drawing without using the following hint(s). If you getstuck and can't complete it on your own, use the following hint(s) to help you.
