WORKBOOK 25

2D COMPUTER AIDED DESIGN WORKBOOKS Level 2

PICTORIAL VIEWS (Isometric)

2D CAD Level 2 using AutoCAD 2013

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Blank Sheet

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2D CAD Level 2 using AutoCAD 2013

OBJECTIVES At the completion of this Workbook you should be able to: 

Appreciate the use of the lsoplane command to produce Isometric pictorial drawings.



Use the Ellipse command to produce Isometric circles.



Substitute the Copy command in place of the Offset command.

************************************************************************************************************** There are two ways that AutoCAD uses to transform a 2D object into a 3D looking image, (i)

drawing a 2D Isometric drawing using the command lsoplane to give the impression of a 3D object.

(ii)

extruding a 2D object into a 3D projection.

Note:

Isometric drawings are created by the lsoplane command, which gives you a 3D visualisation, but not a true 3D image, it will always remain 2D.

This workbook will only cover option (i), 2D Isometric drawing. (i) Isometric drawing ISOPLANE The lsoplane command sets the working plane. There are three working planes, namely: RIGHT plane

(axes 30 - 90)

LEFT plane

(axes 150 - 90)

TOP plane

(axes 30 - 150)

See the illustration below. Only one plane can be worked on at any one time.

Start from Scratch a New drawing using ‘acadiso’ template. Set the drawing limits to 297, 210mm (A4) and Zoom Extents. Create and make current, Layer1, to try out this method of drawing. We shall construct the initial isometric drawing as shown below.

2D CAD Level 2 using AutoCAD 2013

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Before drawing can commence, it is necessary to set the working plane (Isoplane). Like so many AutoCAD commands, the lsoplane working plane can be controlled in more than one way. Consider firstly the Drafting Settings dialogue box. Typed command:

DSETTINGS 

The Drafting Settings dialogue box is displayed.

Ensure the Snap and Grid tab is current. In the Snap type Sector Click on the Isometric snap radio button. Note that both the Grid X spacing: and Snap X spacing: boxes are greyed out, once Isometric snap is picked. What has happened is that the spacing has been modified to accommodate the 30 angle. Click:

OK

The graphic screen displays the cross-hairs, with the horizontal line rotated through 30. If the working plane is not exactly as shown don’t panic.

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2D CAD Level 2 using AutoCAD 2013

Use Function key F5 (or Ctrl+E) to toggle through the three working planes. When you feel confident leave the left working plane as current (Note, the Command: line displays what working plane is current). Ensure ORTHO is ON. Install the Line command. System prompts:

Specify first point

Click a point in the centre of the screen. Stretch out the line in the vertical direction (see below) and,

st

1 point

Type:

80  (using direct entry method for specifying coordinates)

System prompts:

Specify next point or [Close/Undo]:

Move the cursor to change the line direction to the horizontal.

Cursor

and again, Type:

80 

2D CAD Level 2 using AutoCAD 2013

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Repeat the procedure twice (do not use ‘Close’ to complete the box) to produce the left side of the isometric cube.

Line still attached

Now, toggle the lsoplane working plane but this time using the keyboard. Press:

CTRL+E

(Use the Ctrl+E keys together)

Repeat again until the right working isoplane is reached. System prompts:

Specify next point or [Close/Undo]:

Note that the cursor crosshairs have changed to the right working plane. Draw a further 80mm square on the right working plane.

Type:



(to finish the Line command)

Re-install the Line command and finish the top of the cube. Use CTRL+E, (or F5 function key), to toggle to lsoplane Top. You should now have completed the basic cube shape shown on Page 3. ISOCIRCLE Isocircles are a means of creating circles on Isometric planes. In reality they are ellipses, however, they also have a centre point and quadrants like circles. To achieve the ellipse on the top-working plane of the example, select the Top Isoplane, using CTRL+E, or toggle function key F5, if not already there. Install the Ellipse command.

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2D CAD Level 2 using AutoCAD 2013

 Home  Draw  Ellipse

OR

Draw TB

 Axis, End Typed command: System prompts:

Note:

ELLIPSE 

_ellipse Specify axis endpoint of ellipse or [Arc/Center/Isocircle]:

1.

The lsocircle prompt is only offered if Isometric has been previously set to ON.

2.

The Ellipse command ‘Center’ option does not offer Isocircle.

Type:

I 

System prompts:

Specify centre of isocircle:

(for lsocircle)

The ellipse can now be placed at the appropriate position in the middle of the Top working plane. Click the position of the required centre point. Hint:

To find the exact middle of the Top box. Draw a dialogue line between two opposite corner and then select MIDpoint for the centre. Another possibility is to use Polar Tracking with the angles set up (30) as specified previously. System prompts:

Specify radius of isocircle or [Diameter]:

The Isocircle edge is attached to the cursor. Type:

20 

Now toggle to the remaining planes, and draw the same size Isocircle on each plane.

Before we move on, the next objective is to insert centre lines to each of the isometric circles. Create a new Layer called CENTRE LINE, coloured Cyan with a ‘Centre2’ linetype. Make the Layer CENTRE LINE current and draw in the centre lines as shown below.

The next objective is to insert a clevis pin through the cube. 2D CAD Level 2 using AutoCAD 2013

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Take a time out ******************************************************************************************************************************* As the isometric drawing is constructed with 30º angles the best command in AutoCAD (Offset command) is made redundant. Take heart, it can be substituted by the Copy command . Note: Not the windows copy and paste. ******************************************************************************************************************************* On, with the task. Ensure the Isoplane Right is current. Install the Copy command System prompts:

Select objects:

Click on the cube’s left side isometric circle(ellipse) and centre lines. The circle and centre lines are highlighted. System prompts:

Select objects:

Type:



System prompts:

Specify base point or [Displacement] :

Click a point near the isometric circle (this position is not important) and stretch out away from the cube.

System prompts:

Specify second point or [Exit/Undo] :

Type:

40 

The copied isometric circle is position 40mm away from the cube face.

The isometric circle side lines are now to be added. Set the Osnap QUAdrant option in running mode. Install the Line command once again and draw in the two side lines using Osnap QUAdrant.

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2D CAD Level 2 using AutoCAD 2013

The isometric circles and lines now appear as an extruded shaft coming out of the cube. Install the Trim command and remove the hidden parts behind the extruded shaft to get a better picture.

At this point you may be wondering why the centre lines have been added, as they tend to clutter up the drawing. Believe me, they become a very important part of the isometric construction, especially when trying to find hidden centres, etc. The clevis pin we are drawing has a shoulder, position against the back face of the cube. Draw a centre line along the clevis pin. Copy the centre lines from the hole in the left face of the cube 80mm to the back face. It should look like this.

Change the Isoplane to Left (F5 button). Install the Ellipse command (don’t forget to choose Isometric option) and when, System prompts:

Specify centre of isocircle:

2D CAD Level 2 using AutoCAD 2013

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Click on the copied centre lines at the back of the cube. The isometric circle diameter is to be 40 mm Rad.

Change the Isoplane to Right. Install the Copy command to elongate the clevis pin shoulder 15mm and then add the side lines (using QUAdrant Osnap. It should look like this.

Trim the overlapping parts to produce the following.

The next step is to add two 15mm radii to the top two corners. Change the Isoplane to Left. Install the Copy command and copy the vertical line15mm along the left face.

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2D CAD Level 2 using AutoCAD 2013

Change the Isoplane to Right. Repeat the same process with Line 2 to create an intersection for the centre of the radius.

Change the Isoplane to Left. Install the Ellipse command (don’t forget to choose Isometric option) and when, System prompts:

Specify centre of isocircle:

Click on the radii intersection. The isometric circle diameter is to be 15 mm Rad.

Trim the ellipse, corners of the cube and remove the copied lines, to produce the following.

2D CAD Level 2 using AutoCAD 2013

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Change the Isoplane to Right. Copy the radius 80mm back to the cubes back face and trim corners.

Generate the same radius on the other top corner in the same manner as before.

The right and top isometric circles are to be assumed to be holes so part of the pin will be visible. Install the Extend command and stretch the pin to be shown through the holes window. Trim to finish.

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2D CAD Level 2 using AutoCAD 2013

SUMMARY 1.

lsoplane sets the correct working plane (Right, Left, Top) for creating Isometric drawings.

2.

Isometric Snap and Grid Style allows you to use a snap and grid for Isometric drawings.

3.

Ellipse, lsocircle can only be used to draw a circle on an Isometric projection.

4.

The Copy command must be used in preference to the 2D Offset command.

TASKS Task 1 A washer, pin, legs and cap head screws, etc. are to be added to complete the cube assembly.

Save As.. XX25A

2D CAD Level 2 using AutoCAD 2013

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Task 2 Now draw the following and add the text only.

Hint:

Notice that in this example the text is aligned with the Dtext. This is achieved by using two Text Styles in ° ° the dimensioning. One Text Style has 30 rotation while the other has –30 rotation

Save As XX25B.

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2D CAD Level 2 using AutoCAD 2013