EF101 Analysis & Skills Module 2.3 Engineering Graphics Revolved Features Placed Features Work Features Module 2.1, 2.2 Review What are the three types of operations for adding features to the base feature? What command do you use to change the sketch plane? What shortcut-key do you use to switch the current view to the sketch plane view? How do you start sketching your base feature in AutoCAD s definition of the front view? Right side? What two pieces of information are required to define a new sketch plane? What command must you do before you can add dimensions and constraints to a sketched polyline? On-line Help Two Locations Help AutoCAD Help User Interface 2D drawing Plotting Rendering Help Mechanical Help Topics Profiles Features Parts Assemblies Drawings Sketched Features and Operations Join Cut Intersect Extrude Revolve Sweep Images Showing Examples of Sketched Features with Various Operations 1
Placed Features Holes Fillets (Rounds) Chamfers Revolved Feature Requires a sketched profile Requires an axis of revolution Part Sketched Features Revolve Operation (Base, Cut, Join, Intersect) Termination Options (Angle, Full, etc.) Pattern Shell Images Showing Examples of Placed Features Revolved Feature - Details Revolved feature consists of: simple closed profile revolve axis Revolve axis can be: line of the profile construction geometry (centerline font, part of profile) existing part edge (projected to sketch plane) work axis Restriction: revolve profile cannot cross revolve axis Revolved Feature More Details If the revolve axis needs to be offset from the sketch, you need to be able to draw the centerline and include it in your profile: Sketch the desired axis as a centerline before you profile. Design Centerlines Centerline or Design Line, select line, right click, Properties, change the line type Profile the line AND the cross section with the Part Sketch Solving Profile menu (not Single Profile) If you need to add an axis to an existing profile, you can use Part Sketch Solving Append. 2
Display Variables for Curved Surfaces viewres: controls smoothness of curves range 1 to 20000 (default is 100) larger is smoother facetres: controls smoothness of rendered images range 0.1 to 10 (default is 0.5) larger is smoother to take effect switch to wireframe mode facetres, 10 AMUPDATE, ALL switch to shaded mode dispsilh: controls display of contour boundaries of curved surfaces (silhouette curves) 0 - do not display (default) 1 - display slower display if you have many curved surfaces allows selection of surface extents for dimensioning isolines: Controls the number of equally spaced curves used to represent a curved surface. Range 0 to 2047 (default is 4) Feature Modification Selecting a feature in the browser window causes it to be highlighted in the active view To modify - double click (or right click, Edit) on feature s icon in browser window When modifying a feature: First display is the dialog box with feature options After you finish the dialog box, you are prompted to select dimensions to change Click on a dimension and enter the new value. Press Enter again to end selection. Part should update. If it doesn t, use the Part Update menu Hardest part is finding the right dimension to select. May require zooming and/or rotating. Can NOT add or delete dimensions or constraints this way Sketch Editing To add or delete dimensions or modify constraints, you must edit the sketch Expand the feature tree by clicking the + next to the feature Double click the sketch item associated with the feature. Backs up the part to the time the sketch was made. Make any necessary changes Use Part Update to bring back the later features. If the part fails to update, the easiest way to recover is to use undo to remove the changes just made. If you get an error message about sketch edited state, it means the part hasn't been (or can t be) updated. Other Modification Methods Feature Reordering The order in which features were created can be changed IF there are no dependencies that restrict the reordering. To reorder a feature, just shift-drag and drop the feature in the browser to the desired position. Deleting Features right click on them in the browser window, select delete, indicate Y for OK to delete. may result in the deletion of other (dependent) features. 3
Revolved Feature Try It 1. Sketch the first polyline you ll need to use the A, S, and L options: PL <enter> 0,0 <enter> A <enter> S <enter> 0,0 Click at 2 nd point and 3 rd point L <enter> C <enter> 2. Add dimensions why do you need the 0.0 dimension? 3. Revolve 360 using the horizontal line as the revolve axis 4. Undo back to the point just before you revolved. 5. Draw the centerline, append it to the sketch, and add the 1 dimension between sketch and centerline 6. Revolve again 7. Experiment with facetres, viewres, isolines, and dispsilh variables. You ll need to use the rr command to refresh the display after changing them 2 3 Hole Feature Part Placed Features Hole An intelligent cut Better than extruding a circle Placement The two edges placement option implicitly defines the hole s starting plane. Selected edges must define a plane. Concentric locates the hole along the center of a cylindrical surface. You specify the starting plane. From hole allows the hole to be placed relative to an existing hole To use the On Point option, you must set a sketch plane, define and dimension a work point. We ll cover this later. Watch the preview window in the dialog box for examples. Hole Feature Try It Load 8x8 block 2.0 thick with 1.0 rounded corner from web site Ø 1.0 through hole placed with Concentric option Ø 0.5 x 1.5 deep with Ø 0.88 x 0.38 deep counterbore hole placed with Two Edges option Ø 0.5 through with Ø 0.88 x 45 counter-sunk hole placed with From Hole option Countersunk Thru Hole Counterbored Blind Hole Drilled Thru Hole Rectangular and Polar Patterns Creates an pattern (i.e. multiple identical copies in a regular order) of the selected feature(s). Placed on the current sketch plane Spacing is the total distance between the same point in two different instances. Rectangular Pattern: You specify the number of copies along the rows and columns spaced along the positive X and Y axes of the current sketch plane. Polar Pattern: You specify the number of copies along the rows and columns spaced along the positive X and Y axes of the current sketch plane. The number of instances includes the selected feature. One or more features can be selected for a pattern. Can add or remove features from a pattern after you create it you can suppress one or more elements of the pattern. You cannot pattern the following features: base, shell, pattern, surfcut. 4
Rectangular Pattern Try It Part Placed Features Rectangular Pattern Start with the file from the web site. What is the size of the T? (hint - edit the feature to look at its dimensions) What spacing do you need to have 0.5 in between each copy? Y Y Polar Pattern Try It Part Placed Features Polar Pattern Browser right click on rectangular notch feature, select Pattern Polar Select the large circle to indicate the pattern axis. Browser double click on the Polar Pattern to modify Start With 12 instances full 360 7 instances 180 included angle reverse direction X Rectangular pattern with two rows and three columns. Note the spacing shown is using the incremental spacing option. X ( included spacing) X Rectangular pattern using included spacing and with one instance suppressed. Shell Feature Part Placed Feature Shell Used to "hollow out" an object Envision taking outer surface of an object and adding a thickness to it Can exclude (i.e open up) faces Only one shell feature per part. Will fail if you have features smaller or closer together than the shell thickness. If you have problems, start with a small thickness and then modify Shell Example Try It Start with file from web site (4 x4 x2 block with 2 hole) Part Place Features Shell 0.25 inside thickness Top face excluded Add 0.5 Fillets - easiest way is to select the bottom surface and all four corners during the first fillet command Shell reordered before the hole by dragging in the browser window 5
Work Features There are three types of work features: work planes, work points, and work axes. Work features are special construction features that help you place geometry that is difficult to position parametrically. You can constrain sketched and placed features to a work feature that is constrained to your part. By doing so, you can control the location of the sketched or placed feature by changing the position of the work feature. Use work features to: Build features when the faces and edges of a part are not sufficient for the placement of sketch planes. Establish a plane or an edge from which parametric dimensions and constraints can be placed. Provide an axis or a point of rotation for revolved features and arrays. Work Features Example Try It Create a cylinder or use file from web Ø 2, 5 high Create a work axis at the center of the cylinder Create a work plane parallel to the world XZ plane through the axis. Don t set sketch plane Create another work plane tangent to the cylinder parallel to the previous plane Set sketch plane Create a work point on the tangent work plane Add dimensions to make it 1 below the top, centered on the cylinder Create a hole.25 Ø drilled through hole placed with On Point option Another Polar Pattern Example Part Placed Features Polar Pattern... Selected feature(s) rotated about an axis normal to current sketch plane Incremental, Included, Full, Flip options Try it Set sketch plane to top Part Placed Features Polar Pattern Be sure to select the hole, not the base extrusion Use work axis as rotation axis Use 3 instances, 45 incremental angle Modify hole feature to be 0.5 Ø and blind termination 0.25 deep Add a.05 fillet to one end of the hole Reorder the fillet to be before the pattern Edit pattern feature and add the fillet as a second feature Axial Pattern Example Part Placed Features Axial Pattern... Delete the polar pattern Same as polar pattern, but includes a Z offset Use work axis as rotation axis Use 8 instances, 1 revolution, 0.5 offset Toggle revolution direction and offset direction 6