utoCAD Tutorial 5:
FOR RELEASE 14

PLEASE READ: ___________

These tutorials were designed to be part of the introductory courses taught by the Graphic Communications Program at NORTH CAROLINA STATE UNIVERSITY. All of the directions used in this, and the other tutorials in this series, assume that you are running AutoCAD Release 14 on an NT system. These directions will only work with Release 14. Other versions may not have the same commands or format.

OBJECTIVES:

After this tutorial you will be able to:

  1. configure a new file;

  2. convert a two-dimensional object to polylines;

  3. use the EXTRUDE command to create a solid from an object made of Polylines; and

  4. use the REVOLVE command to create a solid from an object made of Polylines.

STEP 1

In this tutorial, you will configure an AutoCAD file, use it to create an advanced solid model, and convert the model to a multiview drawing through the Solview and Soldraw commands. FIGURE 1 provides a preliminary view of the model you will construct, with the subparts identified.

FIGURE 1

Until now, you have used a template file, which I formatted for you. In this tutorial, you will format a file.

Configuring a "template" file is an excellent time saver. If you create similar drawings, you do not have to configure each file.

To start a new file, launch AutoCAD by double clicking on the AutoCAD Program Icon.

As the program opens, a dialogue box will appear that asks if you wish to start a file from scratch or open an existing file. In this box, change the Units to METRIC, select Start From Scratch, and click on OK.

With the default AutoCAD file open, you need to configure the DRAWING LIMITS. Read the information on setting Drawing Limits and then set the limits so that they begin at the 0,0 point and end at 559,432 (the equivalent to a 22 by 17 inch or B size sheet of paper).

Next, load the center and hidden line types. If you need to review this operation, read the information on Linetypes.

To help you better visualize the drawing limits, turn on the grid by double clicking on the GRID button on the Status Line at the bottom of the AutoCAD screen. See FIGURE 2. If you feel the grid spacing is to small, use the Grid command to change the spacing between the grid elements to about 10.

FIGURE 2

Now, save your file under the name acadtutor5.

STEP 2

With your file configured, it is time to construct the model. This model will be fairly large, hence the B size drawing limits.

You will begin by creating a series of two-dimensional elements that can be converted to a solid to form the first part of the model, the Base Plate. The first element you need for the Base Plate is a circle. This circle's center should should be located at the 0,0 point and have a radius of 80mm. See FIGURE 3.

FIGURE 3

 

To the large circle, add a 5mm radius circle that is vertically aligned with the center of the larger circle and 65mm above it. See FIGURE 4.

FIGURE 4

 

With the small circle in place, you will use a new command, called Array, to make multiple copies of the small circle. There are two Array commands in AutoCAD, one for 2D elements and one for Solids. Each Array command is capable of producing two types of arrays, Rectangular and Polar.

Read the information on the Array command. Now, use the small circle to create a POLAR Array that has 20 elements, and is a full 360 degrees. The array's basepoint should be the large circle's center.You will not need to rotate the elements since they are circles. See FIGURE 5.

 

 

 

FIGURE 5

Looks like a good time to save!

With the array completed, you will use the Extrude command to convert the circles to solid cylinders.

The Extrude command can only be used with Polyline (plines) objects that have a "closed path." These include objects like circles and polygons, objects constructed as polylines that have a closed path, and 2D drawings that have been converted to polylines that have a closed path. By "closed path" I mean that each element in the figure is linked to the end of another element without any gaps. See the EXAMPLE to the Right. You may recall that it was necessary to explode the hexagon you added in Tutorial 2 before you could remove two of its sides. This was because it was constructed in Polylines.

You can extrude more than one item at a time as long as they should be the same height. Read the information on the Extrude command and then extrude all the elements you have created so they have a positive thickness of 10mm and are NOT tapered.

When you are finished, the figure will not look any different on the screen. To see the extrusion, you need to change your view point. Use the Vpoint command and ROTATE your view to 300 degrees IN the XY Plane and 35 degrees FROM the XY Plane. The image on the screen should now match the one in FIGURE 6.

FIGURE 6

 

To complete the Base Plate, subtract the small cylinders from the large cylinder using the Subtract command. If needed, you can use the link to review the procedures for this command.

Again, the model will not look any different than the one in FIGURE 6. To check your model, use either the Hide or Render command and then convert it back to its normal wire frame appearance with regen.

Your Base Plate is now complete.

 

Have you saved?

STEP 3

The second part of the model is the Bearing Base. Before beginning the construction of this part, change your Vpoint to 270 degrees IN the XY Plane and 90 degrees FROM the XY Plane. The model will again look like FIGURE 5.

Use the Realtime Zoom (if needed) so you have room on the screen to draw this part of the model to one side of the Base Plate.

The Bearing Base will again be created as a 2D object that you extrude; however, this part will begin as a series of 2D elements that will be edited and then converted to Polylines with the Pedit command.

To construct this part, move to a blank region of AutoCAD's drawing area, to the left of the Base Plate, and construct a circle with a 10mm Radius. Use a left mouse click, in a blank spot of the drawing area, to locate the center of this circle.

Now, you will use a new command, Copy, to create a second circle the same size. NOTE: The Copy command can copy single or multiple items. Read the information on the Copy command and make a copy of the last circle you created. Locate the copy to the LEFT of the original, align it HORIZONTALLY with the original, and 96mm away from the original. See FIGURE 7.

FIGURE 7

Add a construction line connecting the centers of the two circles. Use this line to place a 25mm circle at the line's midpoint so that it is centered between the smaller circles. See FIGURE 8.

FIGURE 8

Keep the line used to add the larger circle. You will use it later to place the Bearing Base on top of the Baseplate.

 

Finally, add tangent lines that connect each small circle to the larger circle, as shown in FIGURE 9. Review the Osnap Tangent command before adding these lines.

 

FIGURE 9

 

 

Trim the circles so they match FIGURE 10.

FIGURE 10

PSST! Save

With the circles trimmed, it is time to turn this figure into a closed set of Polylines with the Pedit command. Read the information on the Pedit command and use its Join option to convert the Bearing Base to Polylines (except for the line down the middle). You now have a polyline 2D object with a closed path. The figure will appear the same when you are done, but you can check it by clicking on one line in the figure. If the figure is a polyline, the whole figure should select.

Before you Extrude the figure, change the Vpoint back to 300 degrees IN the XY Plane and 35 degrees FROM the XY Plane so that you can see the figure as a 3D object after it is extruded. See FIGURE 11.

FIGURE 11

With the drawing converted to Plines, use the Extrude command to convert it to a solid that has a positive height of 20mm and no taper. See FIGURE 12.

NOTE: Remember, if you wanted to extrude the figure in the opposite direction, you would use a negative number for the height. Height is always along the Z-axis.

If your object will not extrude, zoom in close to inspect the intersections of the lines. AutoCAD will not extrude a figure, even if you used Pedit, if there are any gaps in the figure's edge or lines that extend past the intersections. Because of the way a computer monitor displays an image, they may not show at a smaller view of the figure. If this is the problem, undo the Pedit, fix the lines, use Pedit again, and try the Extrude command once more.

 

 

 

FIGURE 12

 

 

 

 

 

 

 

FIGURE 13

Now that you have a solid Bearing Base, you need to place it on top of the Base Plate. Read the information on the Move command and use it to move the Bearing Base so that it is centered with the TOP of the Baseplate.

HINT: Use the Midpoint of the horizontal construction line (used to locate the large circle during the Bearing Base's construction) as its basepoint and an absolute coordinate for the Bearing Base's new location. The absolute coordinate should be 0,0,10, since the Bearing Base must sit on top of the Baseplate, and the top of the Baseplate's center is 10mm above the 0,0 point. See FIGURE 13.

 NOTE: You can use a coordinate or an Osnap to select the Basepoint during the Move command. If you use an Osnap, the element you use as the Basepoint does not have to be part of the object you are moving. In the move you just completed, the line at the bottom of the Bearing Base was not part of the extruded part, but was used to locate the center of the bottom of the Bearing Base. When needed, you can temporarily add elements to a figure for this purpose. This is the same as adding construction lines in a manual drawing.

 

STEP 4

For the last part of the model, you will create a cylinder with a chamfered counterbored hole by revolving a 2D Polyline 360 degrees to form a solid. The Revolve command can be used to create a circular or arched shape from any set of closed plines.

First, you need to set your UCS to a FRONT orientation. Because the objects you have drawn are circular, the 3 point option under the UCS command is not practical. So, this time you will use the X option. The X, Y, and Z options under the UCS command allow you to rotate the UCS about one of these axes. You only have to tell AutoCAD the axis to use, how many degrees you wish to rotate the UCS around the axis, and in which direction (Positive or Negative). To know whether to use a positive or negative number, you must remember that COUNTER CLOCKWISE is POSITIVE and CLOCKWISE is negative. In this case, use the X option and rotate the axis 90 degrees.

Use the RIGHT HAND RULE and place your fingers in a WORLD orientation, see the FIGURE to the LEFT. Your thumb is the X axis. To change to a FRONT orientation, you would have to rotate your hand 90 degrees counter clockwise about your thumb.

You can recognize that you have made the proper UCS change by observing the position of the UCS icon, which should match the one in the figure to the Right.

You will begin the construction of the Counterbored Cylinder the same way you began the last one, as a series of lines that you will convert to a Polyline.

Change your Vpoint to 270 degrees IN the XY Plane and 0 degrees FROM the XY plane. You should now be looking directly at the FRONT surfaces of the Baseplate and Bearing Base. This is also a good time to see if the Bearing Base is properly oriented to the Baseplate. If they are not correctly aligned, use the Move command to reposition the Bearing Base.

Look at FIGURE 14, which shows a diagram of the 2D figure you will create and provides the dimensions to create it. Again, construct this figure in blank space on AutoCAD's drawing area. It will be moved into place after you convert it to a solid.

 

FIGURE 14

Using the diagram in FIGURE 14, create this structure. If you need to review the Relative Rectangular or Relative Polar coordinates, use the LINKS in the LEFT PANEL. See FIGURE 15 for a view of the 2D figure when you are done.

FIGURE 15

Notice that you were asked to add a line to the right side of the "closed" figure, which was 5mm from it. This is a construction line you will use as the axis of rotation when you rotate the figure. This will create an opening through the Chamfered-Counterbored Cylinder.

Once the figure is complete, convert it to a "closed" Polyline path with the Pedit command.

Read the information on the Revolve command and follow the directions below.

 

  1. Activate the Revolve command.

  2. Select the figure you just converted to Polylines.

  3. Use the default option for the Axis of revolution of <Start point of axis> and an Osnap to select one end of the construction line that is 5mm away from the structure.

  4. When asked for the End of the Axis:, use an Osnap to select the opposite end of the same construction line.

  5. When asked for the Angle of revolution:, use the default of <full circle>.

 

Your figure should now look like a cylinder with a counterbored hole and a chamfered edged as it would appear from a FRONT view (see FIGURE 16).

FIGURE 16

To see the Counterbored Cylinder as a 3D object, change your viewpoint to 300 degrees IN the XY plane and 35 degrees FROM the XY plane (see FIGURES 17).

FIGURE 17

 

STEP 5

In this step you will combine the Counterbored Cylinder, the Bearing Base, and the Baseplate into one model. When placing the Counterbored Cylinder on top of the Bearing Base, you will need to be sure you are selecting the correct basepoint on the solids so they will be correctly aligned.

See FIGURE 18.

Use the Move command and select the Center of the BOTTOM of the Counterbored Cylinder as the basepoint for this move. When asked for a second position, select the Center of a TOP EDGE of one of the larger arcs on the Bearing Base. See FIGURE 18 to view the Counterbored Cylinder placed correctly in relationship to the other two solids.

HINT: To select the center of these features, you must place your cursor on the circle's edge. Be careful to place the cursor on the correct circles. It can sometime be tricky to select the correct circle when the model is in wireframe. You can always use the Hide command first to make sure you are selecting the correct elements.

FIGURE 18

To check the placement of the Counterbored Cylinder, change your viewpoint to 270 degrees IN the XY plane and 0 degrees FROM the XY plane (a front view). If the Cylinder is not correctly placed, you can see that it either sits above the Bearing Base or extends down into it. It should look like FIGURE 19.

Because you are viewing the solids as wireframes, which saves computer resources, it is not always easy to tell where the solids intersect with each other. Changing your viewpoint is one strategy you can use to check this. Accuracy counts, and it pays to "measure twice and cut once" before you combine the parts into a single model.

 

FIGURE 19

If the parts are correctly aligned, change your Vpoint back to 300 and 35, and use the Union command to merge the three parts into one.

NOTE: Notice that you were not told to combine the three solids until they were all complete. If you union or subtract parts of a model and later discover that the placement of some features are incorrect, they can be hard to fix. Keep things as individual items and union or subtract them after you are sure that all the elements of the model are correctly constructed and positioned.

With one solid to work with:

  1. Change the UCS back to a WORLD orientation.

  2. Use the Cylinder command to create two 5mm radius cylinders, concentric with the smaller arcs on each end of the Bearing Base, that have a height of 20mm. See FIGURE 20. HINT: Use the Center Osnap to locate the cylinders; however, if you select the arcs at the top of the figure to locate the cylinders, you must use a negative height.
    FIGURE 20

  3. Now, subtract the cylinders from the Bearing Base.

  4. Add another cylinder that continues the smaller center hole in the Chamfered-Counterbored Cylinder through the rest of the model. This cylinder should start at the BOTTOM of the existing small hole in the Counterbored Cylinder, have a radius of 5, and have a height of 30. See FIGURE 21.
    Should you use a positive or negative height in this case?

FIGURE 21

In the last step, you could have used a height that was more than needed. Since you will be subtracting this cylinder, a larger height does not matter.

Use the Subtract command to remove the cylinder you just added to create a through hole.

 

STEP 6

With the model complete, you need to use Solview to create a front, top and right side multiview orientation of the figure, followed by Soldraw to extract the 2D images.

Below is a brief list of things to help you remember the steps for this conversion. You can also refer to the list of AutoCAD Commands Explanations in the area to the LEFT of this screen if the hints are not enough to get you through this process. I would suggest you first try to proceed on your own, since you learn more that way. If you need more help, you can refer to Tutorial 4 to complete these tasks.

Solview & Soldraw:

  1. Change to a FRONT UCS before beginning the Solview command.

  2. Use Realtime Zoom to zoom out before you use Solview. THIS PUPPY IS BIG!

  3. The Solview command is activated by typing solview at a Command: Prompt.

  4. You will be moved to PAPER side of Paper Space.

  5. For the FRONT view, use the Ucs option, and a scale of 1.

  6. The View center can be changed until it correctly placed.

  7. When creating a Clip Path, make sure it is large enough to accommodate the addition of center lines. NOTE: If you get the viewports too small, you can stretch them later.

  8. Name the Front view FRONT.

  9. After the Front view is placed, use the Ortho option of Solview to place the other two views. Name the Top view TOP and the Right Side view SIDE.

  10. The hidden lines will not appear until you complete Soldraw.

  11. If you need to ZOOM across all of the views, make sure you are in the PAPER side of Paper Space before you Zoom. If you accidentally Zoom in the MODEL side of Paper Space you will need to use Zoom XP to return the images to the same scale, and Mvsetup to realign the views.

    FIGURE 22

  12. Activate Soldraw, to convert the views on the screen to 2D images by typing soldraw at a Command: prompt.

  13. After Soldraw is completed, you must change the color of the Front-hid, Side-hid, and Top-hid to a color other than white through the Layer command so they will print in the proper line thickness.

  14. Create a Front-cen, Side-cen, and Top-cen Layer. Change their color, to something other than white, and assign the Center Linetype to them through the Layer command.

Have you saved lately????

STEP 7

With Soldraw completed, you need to make a few modifications before inserting the Titleblock.

While in the PAPER side of Paper Space, Zoom into the FRONT View.

Change to the MODEL side of Paper Space. Be careful not to Zoom at this point or you will change the size of the Front view relative to the other two views.

In FIGURE 23, you will notice that only three holes are represented by hidden lines in the Base Plate area of the Front view, the two small holes on the left and right and the taller hole that extends from the bottom of the counterbore. If you examine your drawing, you will see a huge number of hidden lines in the Base Plate that represent the edges of the arrayed holes. Simplifying this type of view is a common practice in technical graphics known as REVOLUTION CONVENTIONS. Removing most of these hidden lines creates a simpler drawing that is easier to understand.

FIGURE 23

To apply the concept of REVOLUTION CONVENTIONS to your drawing, you will erase all of the hidden lines in the Base Plate except the two for the tall center hole, which extends from the bottom of the Counterbored Cylinder, and the hidden lines that form the outside holes on either end.

FIGURE 24

How do you know which they are? I'll tell you.

Erase most of the hidden lines in the Base Plate area of the model except:

--the short lines on the outside edges of the Baseplate,

-- the third short line in from the outside edges of the Baseplate, and

--the two that extend from the base of the Counterbored Cylinder.

Repeat this process for the Right side view. Refer to FIGURE 24 to check your modifications.

 

Now, add center lines where needed. Use Center Marks (under the Dimensioning Menu) for the small holes in the Top view. See FIGURE 25.

FIGURE 25

  1. When adding center lines, you must change the UCS and Layer to match the appropriate view. Use ltscale (Linetype Scale) to change the length of the dashes in the hidden and center lines to a factor of .5.
  2. Use Vplayer for each viewport to freeze the center lines placed in other viewports so they are not displayed. NOTE: If you find that the wrong center lines disappear during Vplayer, undo the last steps, and check to see if they were drawn in the correct layer. This is easy to do through the Layer Status Window (see FIGURE below). Select a line, and the name of the layer on which that line was drawn will appear in the Layer Status Bar window. If you need to move the line to a different layer, select it, and then select the layer name in the Layer Status Window drop-down menu. Press Ecs.
  3. To make the Floating Viewport borders invisible, change to the PAPER side of Paper Space and click on the light bulb located by it on the Layer Status Bar.

Insert the Titleblock in the 0 Layer. You will have to enlarge it as it is inserted to fit around the drawing. Remember the titleblock's enlargement scale factor, so you can reverse the scale factor when printing.

Move the titleblock so that the drawing is centered, Explode it, use ddedit to edit the text, and print.

Well you completed another one!

Pat yourself on the back for a good job.

There is only ONE more AutoCAD Tutorial left on dimensioning.

AutoCAD is a registered trademark of AutoDesk, Inc.

AutoCAD Tutorial 5: For Release 14 was written by:
Dr. Alice Y. Scales, Ed.D.
Graphic Communications Program
Department of Mathematics, Science and Technology Education
NORTH CAROLINA STATE UNIVERSITY
With contributions by Russell R. Downs

This work is copyrighted and the property of Alice Y. Scales and is not to be copied without permission of the author.

10/14/98

Revised 6/28/00

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