SolidWorks 2010- P9

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SolidWorks 2010- P9

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SolidWorks 2010- P9: Whether you are a new user of SolidWorks or a professional who wants to improve your skills, this book was written for you. Learning any software can be difficult at times. You launch the software for the first time, and you feel overwhelmed, not knowing how to even start a new document. In 3D CAD programs, it can be especially difficult. Many times a whole new vocabulary and a whole new creative environment are introduced.

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Dimension Sketches with Centerlines 209 Dimension Sketches with Centerlines By now you have surely become comfortable with adding dimensions to fully define sketches. Now it is time to introduce another cool dimensioning trick with sketches. As you know, clicking two points or sketch segments will define the distance between the two entities. But since your sketch has a centerline that represents the axis of revolution for the part, you can use that centerline to define the diameter of the part even though only half is shown in the sketch. This is a great way to control the design intent of the part since you are probably more apt to require the diameter controlled rather than the radius. Specifying the diameter of a sketch feature is extremely easy if you already know how to add a dimension, as you will see in the following steps: 1. Select Smart Dimension in the shortcut bar. 2. Select the vertical centerline, and then select the short vertical seg- ment at the bottom of the sketch. 3. The dimension placement is important for how you want to define the sketch. On one side of the centerline, the dimension will be the distance from the centerline to the sketch segment or the radius of the shaft (see Figure 5.9). F I g u R e 5 . 9 Defining the radius of a part 4. Move the mouse pointer to the other side of the centerline, and the dimension changes to show the diameter of the shaft. With the
210 Chapter 5 • Creating a Revolved Part dimension showing the diameter, click and release the left mouse button to place the dimension (see Figure 5.10). F I g u R e 5 . 1 0 Defining the diameter of a part 5. In the Modify window, make the diameter 1.000, and click the green check mark. 6. Making a dimension a diameter also works with points on the sketch. With the Dimension tool still active, select the centerline again, and select the undefined endpoint of the small arc, as shown in Figure 5.11. F I g u R e 5 . 1 1 Defining the diameter from a point on the sketch 7. Move the mouse pointer to the opposite side of the centerline again to make the dimension a diameter dimension, and accept its location. 8. In the Modify window, add the value .900 for the diameter of the shaft at the end of the arc. 9. In addition to lines and points, you can also specify the diameter for an arc at the tangency. Select the centerline again, but this time press and hold the Shift button on your keyboard while selecting the large arc (see Figure 5.12).
Mirror a Sketch 211 F I g u R e 5 . 1 2 Defining the diameter for an arc at the tangent point 10. Move the mouse pointer to the other side of the centerline, and accept the dimension once it changes to a diameter dimension. In the Modify window, specify the value 1.100, and click the green check mark. Rather than specifying the radius of the arc, this approach specifies the diam- eter of the shaft at the largest part of the arc, allowing the radius and length of the arc to float depending on the other dimensions in the sketch. Mirror a Sketch O A centerline rep- Mirroring a sketch or part of a sketch is a great time-saver when areas of the resenting the axis sketch are symmetric. Using a centerline as the mirror point, items that you of revolution for a select can be mirrored so they take on the relations and dimensions specified in part can be used to the original section. If you haven’t used another CAD package that has a mirror define the diameter function, the length of the mirror line does not matter; instead, the actual angle of the part. used is important. This should become clear as you use the Mirror tool in the next few steps. 1. Before mirroring the sketch, you need to finish dimensioning some items. Select the small vertical segment that makes up the 1.00 diam- eter, and place the dimension to the side. In the Modify window, add the value .250.
212 Chapter 5 • Creating a Revolved Part 2. Next, select the horizontal line at the bottom of the sketch. Then select the under-defined point at the end of the short arc, and place the dimension so that it is shown as a vertical dimension. In the Modify window, make the value .350. 3. Press Esc on the keyboard to exit the dimension mode. 4. Double-click the scroll wheel or press F on your keyboard to fit the entire sketch into the graphics area. 5. Select the Sketch tab on the CommandManager, and click the Mirror Entities button. 6. Select all the sketch entities that are not centerlines. The easiest way to do this is to window over the sketch selecting all the items. Then while holding the Ctrl key on the keyboard, deselect the centerlines. 7. Ensure that Copy is selected in the Mirror PropertyManager. 8. Next click the Mirror About field in the Mirror PropertyManager. 9. In the graphics area, select the horizontal centerline. A yellow pre- view will show what the mirrored entities will look like in the graph- ics area (see Figure 5.13). 10. Click the green check mark in the PropertyManager to accept the mirror sketch entities. The sketch now contains the mirror image of the lower half of the shaft above the mirror line with the same size and relations defined in the original section (see Figure 5.14).
Mirror a Sketch 213 F I g u R e 5 . 1 3 Preview of mirrored entities F I g u R e 5 . 1 4 Part of a sketch created through mirroring
214 Chapter 5 • Creating a Revolved Part Trim Sketch entities Even the most perfectly planned sketch will require segments to be trimmed. As you build your sketch by adding sketch entities, you will often be required to trim a segment using an existing sketch entity as the trimming plane. Even the small- est line that is not properly terminated will cause issues when you attempt to cre- ate a feature. In your sketch, you will be adding one last sketch entity that will be used to complete the profile, and you will need to trim all the segments to create one continuous profile. But first you need to add the last entity. Here’s how: 1. Select the Circle command in the shortcut bar. 2. Move the mouse pointer to the middle of the sketch, onto the point where the two large arcs merge, and click the left mouse button. 3. Move the mouse pointer away from the point selected until the radius of the circle is about .150, as shown next to the mouse pointer in Figure 5.15. Click and release the left mouse button to create the circle. F I g u R e 5 . 1 5 Using the Circle command 4. Open the shortcut bar, and select Trim Entities. In the Trim PropertyManager, you will notice there are five different ways to use the Trim tool. Each has its strengths and weaknesses, and rather than show you how to use each of them at this point, we’ll just briefly touch on each of them. Power Trim The Power Trim option allows you to trim multiple sketch enti- ties by dragging the mouse pointer across the segments to be trimmed. This is
Tr i m S k e t c h E n t i t i e s 215 extremely helpful when you have many items that would be too tedious to indi- vidually select. Corner Trim The Corner Trim tool trims or extends line segments to create a corner. If a selected segment is too short to meet where the obvious corner should be created, the segment will extend. Trim Away Inside The Trim Away Inside tool allows you to select two sketch entities and then trim away nonclosed sketch entities that intersect with both of the selected entities or none of them. An example of a closed sketch entity would be a circle. That means even if a circle crosses both of the selected items, it could not be trimmed with the Trim Away Inside option. Trim Away Outside The Trim Away Outside tool acts the same as the Trim Away Inside option except sketch entities that fall outside the two entities selected can be trimmed. Trim To Closest The Trim To Closest option is my most frequently used trimming option. We find that this option is the most useful since it trims anything to the nearest sketch entity without the need to preselect a trimming entity. In fact, in this particular sketch, it will be the option that will be used to clean up the profile. To perform the trim, do the following: 1. Select Trim To Closest in the Trim PropertyManager. 2. Select the two arc segments that fall inside the circle to trim off the segment. 3. Then, select the two segments of the circle that fall inside the sketch profile to remove them, making one continuous profile.
216 Chapter 5 • Creating a Revolved Part 4. Click the green check mark in the PropertyManager to exit Trim. 5. Since the ends of the large arcs were trimmed back, the relationship to the original endpoint was lost. You need to ensure that the arcs are still connected to the endpoint of the horizontal centerline to maintain the integrity of the sketch. While holding the Ctrl key on your keyboard, select one of the large arcs and the endpoint of the horizontal centerline. 6. Release the Ctrl key, and select the coincident relation in the context toolbar. 7. Add the coincident relation to the second large arc as well. 8. Select Smart Dimension in the shortcut bar, and click the remaining section of the circle at the middle of the sketch. 9. Place the radius dimension, and enter the radius value of .100 in the Modify window. 10. Now, select the vertical centerline of the sketch, and hold the Shift button on the keyboard while selecting the middle arc segment. 11. Place the dimension, and set the value to 1.250 in the Modify window, as in Figure 5.16. 12. The sketch should be fully defined, as you will be able to tell by all the sketch segments shown in black and the words Fully Defined in the status bar. If the sketch is not fully defined, recheck your sketch for all relationship and dimensions.
Revolve the Sketch 217 F I g u R e 5 . 1 6 A trimmed sketch segment Revolve the Sketch Now that you have fully defined the sketch that makes up the profile for the lamp shaft, you can create the revolved part. All that is required in the sketch is that a centerline be present to use as an axis of revolution and that all the sketch entities be on one side of the centerline only. The profile that will be used must also be a closed profile, but since you created the sketch with an obvious divid- ing line, SolidWorks will be able to place a line along the centerline to close the sketch. To revolve the part, do the following: 1. Select the Features tab on the CommandManager, and click the Revolved Boss/Base button. 2. A SolidWorks message box will prompt you stating that the sketch needs to be closed and asking whether you would like to automati- cally close the sketch. Since you do need it to be closed, click Yes. N O t e Depending on how the sketch was created, SolidWorks will not always be able to properly determine how to close the sketch. This sketch is fairly simple, and it will have no problem, but if there is any doubt, it would not be a bad idea to close the sketch manually with a line connected to the two open ends of the sketch. 3. Since there is more than one centerline in the sketch, the Revolve tool doesn’t know which one will be used to revolve the sketch. This can be seen by the lack of a selected axis of revolution in the Revolve PropertyManager. This means that you must select the vertical center- line that makes up the axis of the sketch manually (see Figure 5.17).
218 Chapter 5 • Creating a Revolved Part F I g u R e 5 . 1 7 Selecting a centerline around which to rotate the sketch The preview in the graphics area will show what the revolved part will look like when created. 4. In the Revolve PropertyManager, the only options that you need to be concerned with are Revolve Type and Angle Of The Revolution. The Revolve Type setting should already be set to One-Direction, and the angle should be set to 360°. If that is the case, click the green check mark to create the revolved part. The base feature for the lamp shaft has been created! See Figure 5.18. F I g u R e 5 . 1 8 Preview of a revolved part
Add a Threaded Boss 219 Now you need to add a few more features to complete the model. Add a Threaded Boss In lieu of adding separate fasteners to assemblies, it is often advantageous to build the fastening feature directly into the part. In this instance, a threaded boss is needed to attach the lamp shaft to the lamp base that would be held in place with a nut. Some designers enjoy modeling threads on a part because they want to show how the threads actually look on the part. Although this approach is very pleasing to look it, it is often still a waste of system resources, not to men- tion time in modeling the threads. Instead of taking the time to model threads onto a part, we always encourage designers to use the Cosmetic Thread option. Using the Cosmetic Thread option in SolidWorks, a simple representation of the thread is shown in the part and assembly. The information also transfers well onto the drawing, giving the reader a representation of the thread that adheres to common drawing standards and that also displays the pertinent thread information for the manufacturer. N O t e Although it is not the case for this project, there will be times when modeling a true thread is required. In those times, the advantages of the actual thread geometry far outweigh the disadvantages. For example, if your part model is to be used for injection-molded parts, using a cosmetic thread may not work with your process, and you would be forced to actually make the thread. Before you can add the threads to the lamp shaft, you first need to add a boss to the bottom of the shaft. This is the portion of the shaft that goes into the hole in the top boss of the lamp base. The next few steps should be pretty straightforward to you at this point since we have covered this process before. 1. Rotate the part around to give you access to the bottom view of the part. 2. Select Extruded Boss/Base in the shortcut bar. 3. Select the bottom face of the revolved part to insert a sketch for the threaded boss. 4. Select the Circle tool in the shortcut bar, and select the origin of the sketch that corresponds to the center point of the circular face. 5. Create a circle and add a diameter dimension of .750 using the Smart Dimension tool selected in the shortcut bar (see Figure 5.19). 6. Click the Exit Sketch button in the confirmation corner to initiate the Extrude command.
220 Chapter 5 • Creating a Revolved Part F I g u R e 5 . 1 9 Sketching a boss 7. In the Depth field in the Extrude PropertyManager, set the depth of extrusion to .375, and click the green check mark. 8. Click or hover over the SolidWorks logo on the menu bar. Select Insert ➢ Annotations ➢ Cosmetic Thread. 9. Select the top circular edge of the boss (see Figure 5.20). F I g u R e 5 . 2 0 Specifying an edge for a cosmetic thread
Add a Threaded Boss 221 10. In the Cosmetic Thread PropertyManager, select the Standard field to display a list of available thread standards. From the list, select Ansi Inch. After you specify the standard, two additional fields that pertain to the Ansi Inch thread standard will appear below the field. In the first of the two new fields, the Type field, ensure that the Machine Threads option is specified. 11. Below the Type field, the second new field is used to specify the thread. In previous versions of SolidWorks, you were required to manually enter the thread size. Unless you already knew the size of the thread you were going to specify, you would need to look up the thread that worked with the diameter of the boss selected. In SolidWorks 2010, based on the diameter of the selected edge, the Size field should already be set to the most thread callout. Many times the coarse thread is considered the most common, but for this design, you require a fine thread since the length of the boss is only .375″. To select the fine thread, click the Size field, and select the 3/4-10 thread size, as shown in Figure 5.21. F I g u R e 5 . 2 1 Specifying the thread size in the Cosmetic Thread PropertyManager 12. Make sure that the End Condition setting, near the bottom of the Thread Settings section, is set to Up To Next. This will make the
222 Chapter 5 • Creating a Revolved Part cosmetic thread end at the next feature, which is where the boss ends on the shaft. Th r e a d S i z e The callout that you used here is a standard thread callout that can be inter- preted by most manufacturers in the United States. Each part of the callout gives the machinist the information necessary to create the thread. The first part, ¾, refers to the actual nominal size of the thread displayed in fractions. Next, the -10 tells the machinist that the thread will have 10 threads per inch. 13. Click the green check mark to create the thread on the boss. A circle shown in a dash line will be added to the part to represent the minor diameter of the thread, and the shaded thread will be shown on the cylindrical face of the boss, as in Figure 5.22. F I g u R e 5 . 2 2 Minor diameter of a thread N O t e If you do not see a shaded thread as shown in Figure 5.22, you’ll need to update your document properties. In the Document Properties tab of the Options window, click Detailing in the left pane, and then select the Shaded Cosmetic Thread option in the Display Filter section.
Add a Revolve Cut 223 Add a Revolve Cut The next feature you need to add to the lamp shaft is a revolved cut that will be used to create a thread relief at the base of the threaded boss. A thread relief is often preferred by machinists since it makes it easier for them when they cut the threads to remove the material that comes off the cutting tool. A thread relief can be done a few different ways, but we like to make the smallest diameter of the relief slightly smaller than the minor diameter of the thread. The relief does not need to be very large, just large enough to allow the machinist to remove the material. To create the thread relief, you need to create a profile of the cutout that will be revolved around the axis. The profile is different from the one that you used for the shaft itself since the profile is not connected to the axis. That and being a cut are the only two things that are different about this revolve feature for this part. But first, you need to add a couple of features to the boss to complete it prior to creating the revolve cut; follow these steps: 1. Select the Chamfer tool in the shortcut bar. 2. Select the bottommost circular edge of the boss. 3. In the Chamfer PropertyManager, set the Distance value to .025, as shown in Figure 5.23. F I g u R e 5 . 2 3 Adding a chamfer to the boss 4. Accept all the other defaults and select the green check mark to cre- ate the chamfer on the threaded boss.
224 Chapter 5 • Creating a Revolved Part 5. Open the shortcut bar, select the downward-pointing arrow next to the Extruded Cut tool, and select Revolved Cut. 6. In the upper-left corner of the graphics area, the flyout FeatureManager can be accessed by clicking the plus (+) next to the model name. After expanding the FeatureManager, select Front Plane to insert a sketch for the revolved cut. 7. Press Ctrl+8 on the keyboard to change the view to normal to the Front Plane. 8. Zoom in closer to the threaded boss since you will be creating a sketch in that area. 9. Select the Centerline tool in the shortcut bar. Draw a centerline from the origin of the part down, creating a vertical centerline through the threaded boss, as shown in Figure 5.24. 10. Open the shortcut bar, select the downward-pointing arrow next to the Convert Entities button, and click the Intersection Curve button. The Intersection Curve tool is one of the most used tools in our arsenal. The tool creates a sketch segment where the sketch plane and a select face intersect. It is extremely handy, such as in this case, when you require a point or line to reference in your sketch that is based on the surrounding geometry. Even though the tool will result in a single straight line in this instance, you can also use the tool can to create a complex line, such as a spline, that traces the contours of a complex face.
Add a Revolve Cut 225 F I g u R e 5 . 2 4 Adding a centerline for thread relief 11. Select the cylindrical face of the boss (Figure 5.25), and then click the green check mark in the Intersection Curves PropertyManager. O You can use the Intersection Curve tool to create a line or spline that traces the contours of a face. F I g u R e 5 . 2 5 Selecting a curved face on which to use the Intersection Curve tool 12. Click the red X in the PropertyManager to exit the Intersection Curve command. 13. Since you need only one of the lines drawn, select the other line and press Delete on your keyboard to remove the line from the sketch (see Figure 5.26). Two separate lines were created when you selected the cylindrical face of the threaded boss since the face is one continuous face that intersects the sketch plane in two places. If you had instead chosen a face that intersects the sketch plane only once, then only one line would be created.
226 Chapter 5 • Creating a Revolved Part F I g u R e 5 . 2 6 Deleting a line where the cylindrical face intersects the sketch plane 14. Select the Line tool in the shortcut bar, and begin the line at the upper endpoint of the line created in the previous step. Click and release the left mouse button to begin drawing the line (see Figure 5.27). F I g u R e 5 . 2 7 Drawing a line to define the trim 15. Draw the line horizontally toward the center of the shaft until the line extends beyond the vertical dashed line that represents the minor diame- ter of the thread. Click and release the left mouse button to draw the line. 16. While the Line tool is still active, draw a short vertical line downward to a length of approximately .050 inches. 17. Next, draw another segment that is approximately 135° from the last segment with the endpoint of the line coincident with the line that was created with the Intersection Curve tool (see Figure 5.28). 18. Press Esc or click the green check mark in the PropertyManager to exit the Line command. 19. Select the Trim tool in the shortcut bar, and ensure that the Trim To Closest option is selected in the Trim PropertyManager.
Add a Revolve Cut 227 F I g u R e 5 . 2 8 Drawing another line to define the trim 20. Trim the excess length of the line that was created using the Intersection Curve command, as in Figure 5.29. Then click the green check mark in the PropertyManager to exit the command. F I g u R e 5 . 2 9 Executing the Trim command 21. Select the Smart Dimension tool in the shortcut bar, and add a diam- eter dimension using the centerline and the short vertical line. Make the diameter .625. 22. Select the leftmost vertical line to add a vertical dimension of .050. 23. Select the leftmost vertical line and the angle line to make the angle between the two 135° (see Figure 5.30). 24. With the sketch fully defined, click the Exit Sketch button in the con- firmation corner to initiate the Revolved Cut command. 25. Since there is only one centerline in the sketch, it is automatically selected in the Cut-Revolve PropertyManager. Accept the defaults by clicking the green check mark. The thread relief is now created by cutting away the material from the threaded boss (see Figure 5.31).
228 Chapter 5 • Creating a Revolved Part F I g u R e 5 . 3 0 Defining the angle for the revolved cut F I g u R e 5 . 3 1 Thread relief Finish the Shaft You are just a few steps away from finalizing the lamp shaft. First you need to cre- ate a hole that extends through the length of the part that will allow the wiring to Now that you’re familiar with many pass from the lamp base up to the shade assembly. In addition to the through hole, of the tools you have you also need to add a threaded hole at the other end of the shaft that will be used been using, the steps to mount the lamp shade assembly. This will help you reinforce the knowledge you will be less detailed. have by allowing you to review the steps that you take. If at any point in the next few steps you forget how to do any of the task, we recommend returning to where the function is described in this or earlier chapters. 1. Select the Extruded Cut tool in the shortcut bar, and select the bot- tom of the shaft on the face of the threaded boss to add a sketch.

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