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. In the Definition section of the dialog box, select the two markers between which to create the joint.
    1. Click the From marker box and select a marker in the work area.
    2. Click the To marker box 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 the Axis of Motion options, 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 engineering connection. 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 Lower limit check box to enable a lower bound in a specific direction.
    2. Select the Value check box to enable an initial value.
    3. Select the Upper limit check box to enable an upper bound in a specific direction.

    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.
    • Right-click a joint and select Definition from the object menu.
  2. In the dialog box, edit the joint parameters.
  3. Click OK.

    Note: To modify the general properties or graphical properties of the element, right-click the element in the tree and select Properties. For more information, see Displaying Properties.