Step 2: Start the Modeling application.
Step 3: Activate the sketch.
Double-click on a sketch curve.
Step 4: View the system applied constraints.
Verify the Show Constraints option is set to Explicit.
The system created constraints are now displayed in the list box. The dialog should look similar to the graphic shown below.
Choose the first constraint in the list.
The object referred to in the list is highlighted in the graphics window. There should be one horizontal line highlighted.
Use the UP and DOWN arrow buttons located to the right of the list box to browse through the constraint list.
Cancel the Show/Remove Constraints dialog.
Notice that there are degree of freedom arrows at each of the sketch points. Even though most of the objects in the sketch have constraints associated with them, the sketch points are free to move in all directions. This is because the system cannot locate any of the points relative to model space.
Step 6: Constrain the location of a point.
Select the lower endpoint of the left vertical line.
Select the vertical datum axis.
Choose thePoint on Curve icon in the upper left corner of the graphics window.
The geometry now changes to follow the constraint. The point at the bottom of the left vertical line is now constrained in the horizontal direction.
Select the horizontal datum axis.
Choose thePoint on Curve icon.
The geometry now changes to follow the new constraint. The shared sketch point at the bottom of the left vertical line is now constrained in both the horizontal and vertical directions. The degree of freedom arrows go away and, due to the horizontal and vertical constraints on the lines that share the sketch point, one of the arrows on the opposite end of those lines has disappeared.
Choose MB2 to cancel the Constraints mode.
Fit the view. (MB3→Fit)
Step 7: Move the datum planes and axes to layer 61.
The datums have served their purpose of locating the sketch. You will now move them to ease selection of objects and clean up the screen display.
Choose Edit→Object Display.
Choose the Class Selection icon in the upper left corner of the
Choose Datums and choose OK.
Choose Select All and OK.
Key in61 for the Layer in the dialog and press Enter.
Step 8: Continue adding constraints to satisfy the stated design intent.
Turnon the Constraints icon. (Insert→Constraints) Hold the Ctrl key down and select the two horizontal lines (1) at the top of the profile.
Choose Collinear and Equal Length.
Use the Esc key to deselect all the curves.
(Edit→Selection→Deselect All).
Select the right side of the arc at the bottom of the slot (1).
Select the short right vertical line (2, but not on the end point).
Choose Tangent.
Create anotherTangent constraint on the other side of the slot, selecting the left side of the arc and the left vertical line.
Hold the Ctrl key down and select the bottom horizontal line and the lower endpoint of the line originating from the arc center.
Choose Point on Curve.
Choose Midpoint.
Use the Esc key to deselect all the curves.
(Edit→Selection→Deselect All).
Select the line (1), shown below, between the midpoint and the arc center.
Choose Vertical.
Adding dimensional constraints to satisfy the controlling portions of the design intent will allow the profile to be changed by modifying the numerical values.
Inferred Dimensions icon.
Key in a value of5 and press Enter.
Notice the curves change color as they become constrained.
Fit the view if necessary.
Select the left vertical line and place the dimension for it.
Change the value to 3.75.
Select the top left horizontal line and place the dimension.
Change its value to .5.
Fit the view if necessary.
Select the left angled line (1) and the top left horizontal line (2), avoiding the end points. Place the angular dimension and change its value to 45°.
Select the right angled line and the top right horizontal line, avoiding the end points. Place this angular dimension and change its value to the ’p’ number assigned to the other angular dimension.
Select the arc at the bottom of the slot. Place the radius dimension and change its value to .25.
Select the line connecting the arc center and the midpoint and place this vertical dimension. Change its value to1.5 and choose Enter.
The Status line now informs you that the sketch is fully constrained. Remember that it is not necessarily required to fully constrain the profile if it is updating in the manner desired.
Step 9: Change the constraints on the sketch to alter the included angle in the notch.
Click on the first angular dimensional constraint that was created and change it from a 45° to 30°.
Notice that the depth of the notch is unchanged as a result of this edit. Should that have not been our intent, we would have to constrain the sketch in a different manner.
Choose theFinish Sketch icon.
Step 10: Close the part.
Activity — Sketching and Constraining a Gasket
In this activity, you will create and constrain a gasket. To efficiently capture the design intent, constraints and dimensions will be added progressively.
The center hole is the origin of the gasket. The three holes are located on a horizontal axis. The lines on the outer boundary of the profile are tangent to the arcs.