Create realistic motion in assemblies

Explore tools for managing motion between components in a vise assembly: joint limits, motion links, contact sets, and motion studies.

Limit the movement of the jaw slider joint

Use the Edit Joint Limits command to limit the movement of the sliding jaw in a vise assembly.

1. If the Data Panel is not open, click Show Data Panel .

2. In the Data Panel, open 6_Assembly Motion from Projects > Samples > Workshops & Events > Adoption Path > Mechanical Assembly > 6_Assembly Motion. The design appears on the Autodesk Fusion canvas.

3. In the 6_Assembly Motion browser, expand the Joints folder.

4. Under the Joints folder, right-click Slider42 and select Animate Joint to view the motion of the vise jaw's slider joint.

   The movement of the jaw is unrealistic because it passes through solid parts on both ends of the vise. You need to limit its movement to reflect real-world physical laws.

5. Press Esc to stop the animation.

6. Use the ViewCube to position the model so you can view it from the side.

7. Right-click Slider42 again and select Edit Joint Limits.

8. In the Edit Joint Limits dialog, specify the following values:

   • Select the Maximum box and enter 1.20 in.

     Alternatively, drag the left blue flag to the left until it comes close to the fixed vise jaw. Leave enough space for the jaw plate, which doesn't move with the jaw in the animation.

     

   • Select the Minimum box and enter 0.20 in.

     Alternatively, drag the right flag to the right to specify the minimum sliding distance.

9. Click OK. Drag the movable jaw to the left and right. Now, instead of passing through parts on either end of the assembly, it stops at the limits you've set.

   On the left, the jaw slides to the approximate point where the two jaw plates come into contact. (There may still be a small gap between the two jaw plates; later, you'll use a contact set to close this gap.) On the right, the jaw slides to the minimum limit.

10. Choose Position > Revert to re-establish the original position of the assembly.

Link the motion of the handle to the sliding jaw

For the assembly to work properly, turning the handle must move the sliding jaw of the vise. Create this relationship by adding a motion link between the two components.

1. In the Model workspace, choose Assemble > Motion Link.

2. In the browser, expand the Joints folder and select the two joints to be linked: Slider42 (the jaw slider joint) and Rev16 (the handle revolute joint).

   An automatic animation shows the handle and sliding jaw moving together.

3. Click OK to save the motion link.

4. Drag the handle or sliding jaw to see that they now move together.

5. Choose Position > Revert to return the assembly to its original position.

Notice that a Motion Link  added to the timeline and to the Joints folder in the browser.

Refine the accuracy of the jaw slider joint limits

Because the maximum limit you previously set for the slider joint was approximate, the jaw plates might not close perfectly. Use a contact set to make the maximum limit precise.

1. In the browser, right-click the jaw slider joint (Slider42) and select Edit Joint Limits.

2. In the Edit Joint Limits dialog, deselect Minimum and Maximum to remove the limits you previously set.

3. Choose Assemble > Enable Contact Sets.

   A Contact Sets  element is added to the browser.

4. In the browser, right-click Contact Sets and select New Contact Set.

5. Select the two jaw plate components.

   

6. Click OK. The movable jaw now slides until the two jaw plates make contact; then it stops.

   Fusion computes the exact maximum limit from the point at which the jaw plates make contact.

Replace the contact set with accurate joint limits

Because contact sets are computationally intensive, they can degrade the performance of your computer, especially if you employ multiple contact sets in an assembly. Use the contact set you created in the previous step to derive the exact maximum distance for the jaw slider. Then edit the slider joint limits to specify that distance, and remove the contact set.

1. Be sure that the two jaw plates are in contact, so that the jaw slider is at its maximum distance.

   

2. In the browser or on the canvas, double-click the jaw slider joint (Slider42).

   On the canvas, the maximum distance dimension of 1.219 in. appears on the slider joint.

3. In the browser, right-click the slider joint (Slider42) and select Edit Joint Limits.

4. In the Edit Joint Limits dialog, specify the following values:

   • Select the Minimum box and enter -0.20 in.

   • Select the Maximum box and enter 1.219 in.

     Because the maximum joint limit for the slider joint now equals the dimension established by the contact set, you can remove the contact set.

5. In the browser, right-click Contact Sets and select Disable Contact. The contact sets element is removed from the browser.

6. Drag the sliding jaw as far to the left as it can go.

   The sliding jaw now stops at the point where the jaw plates come into contact without the computational load of a contact set.

7. Choose Position > Revert to return the assembly to its original position.

Study the motion of the vise assembly

Set up a motion study to view an animation of the sliding and revolute joints in the vise assembly.

1. In the browser, right-click the revolute joint for the protractor (Rev2) and select Unlock.

   The protractor joint was previously locked to prevent movement. Any joint can be locked and unlocked.

2. Choose Assemble > Motion Study. Then select the Rev2 protractor joint in the browser or on the canvas.

   

3. In the Motion Study dialog, double-click the intersection point of the colored horizontal line for the Rev2 joint and the light vertical line for Step 20.

4. In the text box that appears for Step 20, set Angle to 45 deg.

5. In the Motion Study dialog, drag the playhead from 0 to 20 to see the joint open gradually to 45 degrees.

   

6. Double-click the jaw slider joint (Slider42).

7. In the Motion Study dialog, double-click the colored horizontal line for Slider42 halfway between the light vertical lines for Step 20 and Step 40.

8. In the text box that appears for Step 30, set Distance to 0.75 in.

9. In the Motion Study dialog, drag the playhead from 0 to 30 to see the revolute and slider joints move at the same time. Continue to explore the playback and speed control settings in the Motion Study dialog.

10. Click OK. A Motion Studies folder containing your motion study is added to the browser. From there, you can open, edit, or delete the motion study.