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Professional CAD/CAM tools built on Inventor and AutoCAD
Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
Professional CAD/CAM tools built on Inventor and AutoCAD
Learn about the different types of joints to position components together and how to have them interact with each other.
Type:
Tutorial
Length:
8 min.
Transcript
00:03
In this lesson you will start building relationships within an assembly in Fusion.
00:08
Working with building blocks for assemblies, known as components,
00:12
you can start building relationships between these components using joints.
00:16
If you have used other CAD software, you might be familiar with constraints or mates to create relationships between models,
00:23
typically achieved by removing degrees of freedom.
00:27
For example, when moving the Connecting Rod component here,
00:30
it moves freely, with no limitations and no relationship to other components.
00:35
In Fusion, you use joints and as-built joints to create these relationships.
00:41
While joints also work by affecting degrees of freedom, the approach in Fusion is a bit different.
00:47
Rather than removing degrees of freedom one by one,
00:50
you start by limiting all degrees of freedom and then unlock specific ones to achieve your intended motion.
00:57
This method enables you to perform multiple types of constraints or mates in a single command and simplifies the process.
01:04
To use the Joint tool in Fusion, on the Design toolbar, Solid tab, expand the Assemble menu and select Joint.
01:13
Fusion prompts you to select a snap point on the first component.
01:17
Start by selecting the first component you want to move, such as the shaft.
01:22
Place your pointer over an edge, and Fusion detects the center point of the edge as a connection point.
01:29
After making your first selection, a small icon indicates the joint origin, which serves as a reference point.
01:36
When you select a second point, Fusion moves the shaft to form a basic rigid joint and shows a representative animation.
01:43
You can open specific degrees of freedom by clicking the Motion tab and selecting a different motion type.
01:50
Here, set the type to Revolute.
01:53
You can also define the axis, set Joint Motion Limits and replay the animation.
01:59
Click OK to create the joint.
02:01
It is important to note that you need a component that is either Grounded to the top-level parent.
02:06
This is because when you drag a component to test the assembly joints, the entire assembly is affected.
02:13
To ground the Gear Housing, in the Browser, right-click it and select Ground to Parent.
02:22
Once you create the joint, you can click and drag to rotate the component, observing the flag to see how much it has moved.
02:29
To build another relationship, use the Joint tool again.
02:33
For instance, you can relate the gear to the shaft using the same process.
02:38
Placing the pointer over different faces and edges, Fusion shows implicit joint origins,
02:44
such as vertices, midpoints, center points, and centroids, based on your model.
02:50
You can lock onto a face by selecting it, and then you are free to select the origin point.
02:55
Or press and hold Ctrl with the pointer over a face, and the pointer snaps to the nearest origin, making it easier to align components.
03:04
Select the top face, then select the center origin point.
03:09
Next, select the top of the shaft, using the center origin point.
03:14
If the part flips when creating the joint, click the Flip option to fix the orientation.
03:20
Use the manipulators to make changes on the canvas, such as Offset Angle, and in X, Y, or Z.
03:27
Since this component is tied to the rotation of the shaft, on the Motion tab, change the Type to Rigid.
03:35
You can also use as-built joints,
03:38
which are available only in the parametric modeling workspace
03:41
and are designed for components that are already in the correct location.
03:45
For example, in the Blade Holder Assembly, the Reciprocating Rod is already correctly positioned.
03:51
Using an as-built joint enables you to define its relationship to other components without moving it.
03:58
On the toolbar, expand the Assemble menu and select As-Built Joint.
04:03
Select the Reciprocating Rod component, and then the Guide Block component.
04:09
Change the Motion Type to Slider.
04:12
To set the axis, select a horizontal edge on the Blade Holder Reciprocating Rod, then select the origin.
04:20
An animation shows the direction of the slider joint.
04:23
Click OK to create the as-built joint.
04:26
This method is also useful for imported geometry that is pre-positioned.
04:31
Again, you can preview the motion by dragging the Blade Holder Assembly component.
04:37
When creating joints, you can utilize advanced options, such as Between Two Faces, when there is no clear geometry to snap to.
04:45
This is helpful for connecting parts like a crank arm to the end of the Reciprocating Arm.
04:50
Click the Joint tool, and for Component 1, select Between Two Faces.
04:57
Select the first face on the Crank Arm, then the second face.
05:01
Next, select the circular edge as the Snap point.
05:05
For Component 2, again select Between Two Faces.
05:10
Select the upper face on the Reciprocating Rod, the lower face, and then the circular edge for the Snap point.
05:18
On the Motion tab, set the Type to Revolute, and then click OK.
05:23
Lastly, click the Joint tool again.
05:27
Now, select the lower center point on the other end of the Crank Arm and the center of the pin hole on the gear.
05:33
Change the Motion type to Revolute, and then click OK.
05:37
By defining relationships through joints, you can establish a functional assembly with open degrees of freedom.
05:44
In this example, the assembly is created with just a few joints.
05:49
Once all components are defined, you can use any of them to drive the open degrees of freedom and see how the assembly performs.
Video transcript
00:03
In this lesson you will start building relationships within an assembly in Fusion.
00:08
Working with building blocks for assemblies, known as components,
00:12
you can start building relationships between these components using joints.
00:16
If you have used other CAD software, you might be familiar with constraints or mates to create relationships between models,
00:23
typically achieved by removing degrees of freedom.
00:27
For example, when moving the Connecting Rod component here,
00:30
it moves freely, with no limitations and no relationship to other components.
00:35
In Fusion, you use joints and as-built joints to create these relationships.
00:41
While joints also work by affecting degrees of freedom, the approach in Fusion is a bit different.
00:47
Rather than removing degrees of freedom one by one,
00:50
you start by limiting all degrees of freedom and then unlock specific ones to achieve your intended motion.
00:57
This method enables you to perform multiple types of constraints or mates in a single command and simplifies the process.
01:04
To use the Joint tool in Fusion, on the Design toolbar, Solid tab, expand the Assemble menu and select Joint.
01:13
Fusion prompts you to select a snap point on the first component.
01:17
Start by selecting the first component you want to move, such as the shaft.
01:22
Place your pointer over an edge, and Fusion detects the center point of the edge as a connection point.
01:29
After making your first selection, a small icon indicates the joint origin, which serves as a reference point.
01:36
When you select a second point, Fusion moves the shaft to form a basic rigid joint and shows a representative animation.
01:43
You can open specific degrees of freedom by clicking the Motion tab and selecting a different motion type.
01:50
Here, set the type to Revolute.
01:53
You can also define the axis, set Joint Motion Limits and replay the animation.
01:59
Click OK to create the joint.
02:01
It is important to note that you need a component that is either Grounded to the top-level parent.
02:06
This is because when you drag a component to test the assembly joints, the entire assembly is affected.
02:13
To ground the Gear Housing, in the Browser, right-click it and select Ground to Parent.
02:22
Once you create the joint, you can click and drag to rotate the component, observing the flag to see how much it has moved.
02:29
To build another relationship, use the Joint tool again.
02:33
For instance, you can relate the gear to the shaft using the same process.
02:38
Placing the pointer over different faces and edges, Fusion shows implicit joint origins,
02:44
such as vertices, midpoints, center points, and centroids, based on your model.
02:50
You can lock onto a face by selecting it, and then you are free to select the origin point.
02:55
Or press and hold Ctrl with the pointer over a face, and the pointer snaps to the nearest origin, making it easier to align components.
03:04
Select the top face, then select the center origin point.
03:09
Next, select the top of the shaft, using the center origin point.
03:14
If the part flips when creating the joint, click the Flip option to fix the orientation.
03:20
Use the manipulators to make changes on the canvas, such as Offset Angle, and in X, Y, or Z.
03:27
Since this component is tied to the rotation of the shaft, on the Motion tab, change the Type to Rigid.
03:35
You can also use as-built joints,
03:38
which are available only in the parametric modeling workspace
03:41
and are designed for components that are already in the correct location.
03:45
For example, in the Blade Holder Assembly, the Reciprocating Rod is already correctly positioned.
03:51
Using an as-built joint enables you to define its relationship to other components without moving it.
03:58
On the toolbar, expand the Assemble menu and select As-Built Joint.
04:03
Select the Reciprocating Rod component, and then the Guide Block component.
04:09
Change the Motion Type to Slider.
04:12
To set the axis, select a horizontal edge on the Blade Holder Reciprocating Rod, then select the origin.
04:20
An animation shows the direction of the slider joint.
04:23
Click OK to create the as-built joint.
04:26
This method is also useful for imported geometry that is pre-positioned.
04:31
Again, you can preview the motion by dragging the Blade Holder Assembly component.
04:37
When creating joints, you can utilize advanced options, such as Between Two Faces, when there is no clear geometry to snap to.
04:45
This is helpful for connecting parts like a crank arm to the end of the Reciprocating Arm.
04:50
Click the Joint tool, and for Component 1, select Between Two Faces.
04:57
Select the first face on the Crank Arm, then the second face.
05:01
Next, select the circular edge as the Snap point.
05:05
For Component 2, again select Between Two Faces.
05:10
Select the upper face on the Reciprocating Rod, the lower face, and then the circular edge for the Snap point.
05:18
On the Motion tab, set the Type to Revolute, and then click OK.
05:23
Lastly, click the Joint tool again.
05:27
Now, select the lower center point on the other end of the Crank Arm and the center of the pin hole on the gear.
05:33
Change the Motion type to Revolute, and then click OK.
05:37
By defining relationships through joints, you can establish a functional assembly with open degrees of freedom.
05:44
In this example, the assembly is created with just a few joints.
05:49
Once all components are defined, you can use any of them to drive the open degrees of freedom and see how the assembly performs.
In Autodesk Fusion, joints define the relationships between components in an assembly.
Fusion defines relationships between components by using joints and as-built joints, and joint movement provides degrees of freedom. With other CAD tools, you use a constraint or mate to limit one or two degrees of freedom at a time, then add constraints or mates until you have enough degrees of freedom. In contrast, with Fusion you begin by limiting all degrees of freedom and then select a joint motion type that specifies degrees of freedom. This approach allows you to obtain the required degrees of freedom all at once, in one command.
A joint allows a component to move translationally (back and forth) along the X, Y, or Z axis or to rotate around one of these axes. Each joint uses the number of degrees of freedom needed for the intended motion. When you insert a joint between two components, you choose one of the following types:
Rigid. A rigid joint fixes two components to one another. It provides no degrees of freedom.
Revolute. A revolute joint has a single rotational degree of freedom, much like a hinge. This joint can rotate around the standard X, Y, or Z axis, or around an edge in the model (a custom axis).
Slider. A slider joint has a single translational degree of freedom. It is used for components that slide along one another. Options are similar to revolute joint options, except that components slide along the selected axis rather than rotating around it.
Cylindrical. A cylindrical joint provides two degrees of freedom: one translational and one rotational. Components joined with a cylindrical joint always rotate around the same axis.
Pin Slot. A pin slot joint also allows two degrees of freedom, but components can rotate around different axes.
Planar. A planar joint allows three degrees of freedom. It allows two directions of translation in a plane and a single rotational direction normal to that plane. It is useful for joining two components so they can rotate while sliding across the plane.
Ball. A ball joint has two degrees of rotational freedom: pitch and yaw. Pitch allows components to rotate around the Z axis. Yaw rotates components around the X axis.
In this step, you use the Joint command to create a Revolute joint between the shaft and body of a gear housing.
If the Data Panel is not open, click Show Data Panel .
In the Data Panel, open 5_Assembly Joints from Projects > Samples > Workshops & Events > Adoption Path > Mechanical Assembly > 5_Assemblies and Joints.
In the Model workspace, choose Assemble > Joint.
In the Joint dialog, set Motion Type to Revolute.
Fusion enables the required degrees of freedom for the motion type. Fusion automatically chooses the Z axis, but you can specify another axis if necessary.
Select the edge of the shaft. The Joint dialog shows the shaft selected for Component 1.
By default, Fusion offers only one point to connect to; in this case, the center point of the edge.
A small icon called the joint origin appears on the shaft. It is the reference point for the joint on this component.
Select a point on the inner rim of the opening in the gear housing. The Joint dialog shows this selection for Component 2.
The shaft moves to the gear housing and is joined in a revolute relationship.
Click OK.
Rotate the base of the shaft. The rotating flag shows the animation.
Learn more about joint origins as you join the gear to the shaft.
Choose Assemble > Joint.
Zoom in on the gear and hover over the top face.
Different faces of the gear offer different points to place a joint origin. These points are called implicit joint origins. They are automatically generated and typically found on a face or edge.
A circle denotes a vertex.
A triangle denotes a midpoint.
A plus symbol denotes a center point.
A square denotes the centroid of a face.
Next, designate a face for the joint origin. Select the face that contains the hole of the shaft without referencing any of the individual points. The face changes color.
Select the center point (plus symbol) to place a joint origin on the hole for the shaft.
Zoom in to the shaft and select the center point on the top to place a joint origin there.
In the Joint dialog, specify the following values:
Set Angle to 0.0 deg.
Set Offset X to 0.00 mm.
Set Offset Y to 0.00 mm.
Set Offset Z to 3.00 mm.
Notice that you can offset the final position of the gear on the shaft in all three axes and revolve around one of the axes. Also, because Fusion automatically flips the gear, you use the Flip option to put the gear in the correct alignment.
In the Joint dialog, set Motion Type to Rigid to remove all six degrees of freedom.
Click OK.
Drag the gear to preview its circular motion on the shaft.
You used regular joints to move the shaft and gear to their correct positions. Now you can use as-built joints between the connecting rod and block guide components, because they are already in their proper locations.
NOTE As-built joints are available only in parametric modeling, not in direct modeling. You typically use as-built joints in top-down design, where components, including imported geometry, are assembled in place.
Choose Assemble > As-Built Joint.
For components, select the connecting rod and the block guide.
In the As-Built Joint dialog, set Motion Type to Slider.
Select an edge of the connecting rod to specify a direction.
Select the end of the connecting rod edge. Once this end reaches the block guide, the connecting rod will slide no further.
Animation shows a preview of the sliding relationship between the two components.
In joining the crank arm to the connecting rod, you learn how to place a joint origin between two faces when snap points aren't available.
Choose Assemble > Joint.
Move the crank arm to view the sides of the two faces on one end.
Right-click and select Between Two Faces.
Select the upper face.
Select the lower face.
Hold down the Ctrl key (Windows) or Command key (macOS) and hover over the area until you see the center point between the two faces. Select that point for the joint origin.
Hold down the Ctrl key (Windows) or Command key (macOS) and hover over the cylinder at the end of the connecting rod until you find the center point. Select that point for the joint origin.
The crank arm moves to the connecting rod in a rigid relationship.
In the Joint dialog, do the following:
Animation demonstrates the revolving movement of the crank arm on the connecting rod.
Complete the linkage between the gear, crank arm, and connecting rod, and then watch the resulting movement demonstrate the open degrees of freedom.
Choose Assemble > Joint.
Alternatively, because you just used the Joint command in the previous step, you can right-click and select Repeat Joint. In Fusion, the previous command is always shown at the top of the Marking menu.
Rotate the crank arm so that you can view the bottom face.
Click the edge of the hole on the bottom face of the crank arm to select the center point.
Click the edge of the hole on the gear shaft to select the center point.
In the Joint dialog, set Motion Type to Revolute.
Click OK to see the joint take effect.
Now that all the components have been joined, the movement of one them causes the rest to move according to the designated degrees of freedom. Notice that the five joints you have created are shown in the timeline.
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