Controlling Screw Hole Locations with Equations

Add equations to control the locations of the screw holes.

Equations create a mathematical relation between dimensions. You can use equations to locate entities instead of setting explicit dimensions.

In this example, you set one screw hole location to be one half the height of the hinge, and the other screw hole to be one third the length of the hinge. If you change the height or length hinge dimension, the screw holes maintain this mathematical relation.

  1. Add an equation to control the location of one of the points:
    1. In the FeatureManager design tree:
      • Expand CSK for M8 Flat Head Machine Screw1.
      • Right-click the sketch that positions the holes and select Edit Sketch.
      • Double-click the large model face in the graphics area to display its dimensions.
    2. Click Equations on the Tools toolbar. In the dialog box, click Ordered View .
    3. Under Name, click Add equation.
    4. Select the 30mm dimension in the graphics area.
    5. Select the 60mm dimension.
    6. Type /2 in the dialog box to complete the dimension.
      This sets the distance between the point and the bottom edge to one-half the height of the hinge.

      Under Value / Equation, appears, indicating a valid equation.

  2. Add an equation to control the location of the other point:
    1. Click in the Evaluates to box for equation 1.
      The value 30mm appears. A new equation line appears.
    2. Click Add equation.
    3. Select the 40mm dimension.
    4. Select the 120mm dimension for the base.
    5. Type /3 to complete the dimension.
      This sets the distance between the point and the side edge to one-third the length of the hinge. Under Evaluates to, the values should be 30mm for equation 1, and 40mm for equation 2.
  3. Click OK, then close the sketch.