Creating Screw Joints

You can create screw joints to translate and rotate two bodies about the same axis. A screw joint is a combination of a revolute joint and a prismatic joint.

This task shows you how to:

See Also
About Joints

Specify the Definition Properties

  1. From the Mechanism section of the action bar, click Joint .
  2. In the dialog box, select Screw from the list of joint types.
  3. Select the two markers between which to create the joint.
    1. Click the From marker field and select a marker in the work area.
    2. Click the To marker field and select a marker in the work area.

    Tips:
    • To edit the selected markers, click and select Edit. The Markers dialog box opens.
    • To modify your selection, click and select Clear selection. You can select another marker in the work area or in the tree.

  4. Optional: To create the joint using a new marker:
    1. Click Create a new marker .

      Tip: You can also click and select Create a new marker.

    2. In the tree, select the body on which to create the marker.
    3. In the Markers dialog box, define the marker.

      For more information, see Creating Markers.

    The new marker appears in the tree and the name of the marker appears in the box.
  5. From Axis of Motion, select the axis along which the translation or rotation operates.
  6. From the Motion State list, select one of the following types of movement:
    • Translation state: the state is a distance expressed in mm.
    • Rotation state: the state is an angle expressed in deg.
    The selected motion state appears in the States table.
  7. Enter values for the following properties:
    • Screw tangent: distance along the screw axis covered by a rotation of one radian of the screw.
      Note: For an automatic screw joint, the screw tangent is computed based on the distance value specified in the properties of the screw mate. The screw tangent formula is (distance*360deg)/angle, and the result is expressed in mm/turn.
    • Rotation offset (in deg)
    • Translation offset (in mm)
  8. Optional: In the States table, specify values to control the joint motion. To do so, in each row:
    1. Select the cell corresponding to the value to define.
    2. Select the check box under the table.
      The cell appears in blue and becomes editable.

    3. Double-click the cell and specify the value by entering a value or by using the arrows.

      Note: Cells with values specified manually appear with a yellow background.

    Notes:
    • Each row corresponds to a translation or rotation degree of freedom. The number of rows depend on the joint type.
    • If the lower and upper limits are not applicable, no check box appears in the corresponding row or column.

Edit the Joint

  1. To edit a joint, in the tree, do one of the following:
    • Double-click a joint.
    • Click a joint and select Edit Feature on the context toolbar.
  2. In the dialog box, edit the joint parameters.
  3. Click .