cp10165 joints, so much more than just rigid

CP10165

Joints, So Much More than Just Rigid Joel Palioca Autodesk Inc. Sachlene Singh Autodesk Inc.

Learning Objectives Discover and learn how to implement the best joint type for your workflow

Learn how to maximize your joint capabilities inside of a distributed design

Learn how to capitalize on Joint Origins and Contact Sets to create intelligent models

Learn how to use joints to create animations and motion studies

Description Joints are so much more than just gluing components together. What about creating motion and understanding how it interacts with our designs? Joints are far more than just assembly of components; they also describe motion. This class will provide you with an understanding of joints and how you can implement this motion into your Fusion 360 software workflow. You will learn about the different types of joints and the best places to use them. We will also touch on how to approach joints while you’re in a distributed design, and we’ll give you tips to keep your joints organized. Once we understand the basics of Fusion 360 joints, we will move on to positioning them exactly where we want and we’ll address how we can combine them with contact sets to create realistic motion. Lastly, we will take our joints to the next level by studying the motion of the joints and creating a presentation of the motion using animations, all inside of Fusion 360 software.

Your AU Experts

Joel Palioca has been a Software Quality Assurance Engineer at Autodesk for the past 4 years working on Autodesk Product Design Suite, and currently Fusion 360. His time with CAD has allowed him to experience different perspectives on design, manufacturing, and engineering, as well as visualization of applications. Joel has been using CAD for the past 15 years, across a variety of different solutions. His desire to continue learning, and assisting users is what drives Joel every day to produce quality products.

Sachlene is a Technology Evangelist at Autodesk. This gives her the unique opportunity to work with users of design software and make them successful. With a more recent focus on emerging technology companies, Sachlene has played the role of mentor, design advisor, engineer and team member to help startups bring their products to market. She is a Mechanical Engineer, has a Master’s Degree in Mechanical Engineering and has several years of experience in the industry and at Autodesk.

Discover and learn how to implement the best joint type for your workflow

Why Joints? Why are we using Joints instead of a common CAD practice like constraints? This is a common question we get and it really boils down to a mental shift to focus on what should my components do, instead of what they can’t do. When we look at the idea of constraints, we are focusing on locking down available degrees of freedom or DOF to limit our motion. This requires an understanding of basic physics, and the math involved to make certain our models operate according to our desires. With Joints we relate to the motion desired, and only leave open degrees of Freedom required to create that motion. By doing this we simplify the need to understand the physics, and create an understanding between the motion and the result. As we dive into the different types of Joints I will also talk about the degrees of freedom that will be left open to drive our motion.

Imported hinge from McMaster-Carr quickly ready for use with an As-Built joint

Joints, So Much More than Just Rigid

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Joint Basics As we dive into Joints we need to understand some basic principles about how we can interact with the joints that we create and where they are stored in our designs.

Joints are enacted between components, but are commonly defined by certain features within the component, like a body face or edge. For more advanced scenarios we can also create Joint Origins to help facilitate our connection locations.

Tip: When first starting out with Joints it is helpful to ground one component so that motion is more expected. Trying to animate one component’s connection to another is hard to do when neither component is connected to anything. Grounding a component will lock it in place for us.

In Fusion 360 we have 3 different access points we can interact with the Joints that we create. You can find your Joints in the Timeline, Browser tree under Joints, and in the graphics window with each icon. In the browser each component has its own Joints folder, which is important when understanding where our Joints are located.

3 DIFFERENT ACCESS POINTS FOR OUR FUSION JOINTS


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Joint Origins When we start to create a Joint we will see a white disk appear that will snap to pre-generated points in our geometry. This disk or Joint Origin as we call it is a visual representation that allows us to understand how our Joints will be assembled. When we create our Joints we select a Joint Origin on each component to assemble together.

XYZ OF THE JOINT ORIGIN

When we are working with Joint Origins its best to think of them as a coordinate system. Our Joint Origin plane will act as the X/Y plane, the open side of our Joint Origin shows our Y in the positive direction while the line that separates the open and closed sides is our X Axis. The positive for Z points up from the white face, while the negative side for Z points down from the light yellow side of the Joint Origin.

VISUAL DIFFERENCE FOR POSITIVE AND NEGATIVE FOR Z

Joint Selection Order The selection order affects the positive direction of a joint’s movement. The first selection moves along the joint degree of freedom arrow (the blue triangle in the joint display) relative to the second selection. So when the slider value is 25mm, the first selection will be 25mm in the direction of the joint’s degree


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of freedom arrow. For this reason, it is a good practice to first select the object you think of as moving relative to the other.

Another way to thing about this is if you have a door slider lock, the slider should be selected first and the component attached to the door second.

BLUE DEGREE OF FREEDOM ARROW

Joints will still work correctly if you select in the wrong order, but the joint values will be negative of what you are expecting for your result.

As-Built Joint vs Joint You will notice that we have two different types of commands relating to the creation of a joint. The As-Built Joint and the Joint, both are important and have different uses depending on your scenario. Both As-Built Joint and Joint have 7 different types of Joints that can be created. Leveraging the correct Joint Type and command, As-Built Joint or Joint, can help streamline your process to save you time.

OUR TWO JOINT CREATION COMMANDS

As-Built Joint The As-Built Joint is primarily used in the case of imported geometry or top-down design when the components to be constrained are in the correct positions relative to each other, i.e. they don’t need to be moved. An As-Built Joint maintains the positions, and defines the relative motion.

With an As-Built Joint since we do not move the components, the first selection of a grounded component is allowed.

Joint The (Assembling joint) or Joint as we call it in Fusion 360 is used when our components need to be assembled together, or are not already in the correct positions. With Joint we move the first selected component to the location of the second selected component. This allows us to move our components, as well as define the relative motion.

With a Joint our first component will move, so the first selection will NOT allow a selection of a grounded component.


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Joint Dialog Box In the As-Built Joint or Joint dialog box we have a number of different fields that will help us understand what is occurring with our Joint creation. For every Component selection we make below, we have the ability to select a new component with we so wish during the edit of our Joints.

Below we list out all of the options for both As-Built Joint and Joint, denoted each options relation in the title.

JOINT COMMAND DIALOG

Component 1 - Joint Component 1 is where we choose the component that will end up moving to the second component. We can select any Joint Origin on the component for this selection. Pre-generated snap points will be created for you based on different body faces, or edges.

Component 2 – Joint Component 2 is where we choose the component that component 1 will be moving to. We can select any Joint Origin on the component for this selection. Pre-generated snap points will be created for you based on different body faces, or edges.

Components – As-Built Joint Components is specific to the As-Built Joint since the order we choose the components is not important. We select both components before choosing the position which will be based on the pre-generated snap points.

Position – As-Built Joint Position is only shown when we are leveraging the As-Built Joint command after we have selected our components. This allows us to define the Joint Origin that we will be working with. Unlike Joint we don’t define the position when we select the component, but rather afterwards.


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Angle - Joint With the Angle option we are able to specify an angle to rotate the Joint Origin. Note that the movement is specific to the Joint Origin and not used in defining the movement of the joint we have created. When we change the angle of the Joint Origin it allows us to alter the angle of the connection point that the two components are connected.

Offset - Joint With the Offset option we are able to specify a value to offset the Joint Origin. Note that the movement is specific to the Joint Origin and not used in defining the movement of the joint we have created. When we change the offset of the Joint Origin, it allows us to define the offset of the connection point that the two components are connected.

Flip - Joint Flip is the option to reverse the orientation of the Joint Origin. With the Angle, Offset, and Flip options we are able to position our connection point.

Type We have 7 different types of joints within Fusion 360 and each has a different use. For each type of joint we also have a mix of 6 different options available that help us with our joints. These options are Rotate, Slide, Axis, Normal, Pitch, and Yaw. I will go into more detail on each of these options and how it applies to each joint later when we dive deeper into each Joint Type.

Animate Animate allows us to show the allowed motion by animating Component 1. You have the ability to stop the animation from inside of the dialog if you so wish. When we leverage animate from inside of the Joint dialog box, we are using the Animate Joint command, explained earlier, which animates only the Joint in question. This means that outside factors such as grounded, rigid group, motion link etc. will be ignored.

Joint Types In Fusion 360 we have 7 different types of Joints that we can leverage with both As-Built Joint, and Joint commands. Each Joint Type has a different use, and a different number of allowed degrees of freedom to define our motion. Also note that each joint that is created, and the associated values, will also create a parameter that you can alter when in Parametric Modeling. When working with joints keep in mind that keeping the fewest degrees of freedom possible open will help you test your mechanisms the fastest.


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TABLE OFF THE DIFFERENT JOINT TYPE OPTIONS AND THE MOTION ALLOWED

Rigid Rigid is probably the most commonly used Joint Type when starting out. Rigid locks components together, removing all degrees of freedom. An example of when you might want to use this is when two pieces will be welded together, or you are bolting multiple components together in multiple locations so that no motion will be allowed. With the Rigid Joint Type we don’t have any additional options since there is no allowed motion to control.


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RIGID JOINTS

Revolute The Revolute Joint Type allows the component to rotate around the Joint Origin that has been defined. With the Revolute Joint we only allow motion in 1 rotation that we define. We might consider using the Revolute Joint when we need to allow rotation around a single point, but no additional translation should be allowed. Common cases for this are when you are working with linkages or bolted components together around a single point. With the Revolute Joint Type we are able to use the Rotate option to help define which axis we want to rotate around the Joint Origin. We have the option of choosing the X Axis, Y Axis, Z Axis, or a Custom Axis. X, Y, and Z Axis will allow us to use the predefined Axis around the Joint Origin whereas Custom will give us the capability to choose another Axis not on the Joint Origin.

REVOLUTE JOINTS


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Slider Slider Joint allows us to translate a component along a single axis. With the Slider Joint we only allow motion along 1 translation of an axis. A common use for this joint is when a component needs to have the ability to move up and down a rod without rotation. With the Slider Joint we have the option to change the Slide direction based on the Axis we wish. Very similar to Revolute we can choose the X Axis, Y Axis, Z Axis, or a Custom Axis. X, Y, and Z Axis will allow us to use the predefined Axis around the Joint Origin where Custom will give us the capability to choose another Axis not on the Joint Origin.

SLIDER JOINT

Cylindrical Cylindrical Joints allow the component to rotate and translate along the same single axis. With the Cylindrical Joint we allow motion along 1 translation along an Axis, as well as 1 rotation around that same Axis. Cylindrical Joints are great when we need to thread a component through a hole or show the movement of our rod. With the Cylindrical Joint we have the option to change the Axis that is used. We are able to choose the X Axis, Y Axis, Z Axis, or a Custom Axis. X, Y, and Z Axis will allow us to use the predefined Axis around the Joint Origin where Custom will give us the capability to choose another Axis not on the Joint Origin. While the options inside of the Joint Dialog box may look similar to a Slider Joint, one thing to note is that once you have completed the Joint creation, we are able to rotate around the Axis we have chosen. You can see this behavior if you Animate the Joint as well.


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CYLINDRICAL JOINT

Pin-Slot Pin-Slot Joints allow the component to rotate about an axis and translate about a different Axis. With the Pin-Slot Joint we allow motion along 1 translation along an Axis, as well as 1 rotation around a different Axis. Note that Pin-Slot is very similar in behavior to Cylindrical except we are not able to select the same Axis. The Pin-Slot Joint works great when working with a Pin-Slot just as the name says. We are able to allow rotation, as well as the available space within a slot that the component can move. With the Pin-Slot Joint we have the option to change the Rotate and Slide Axis that are used. We have the same Axis available to us, X Axis, Y Axis, Z Axis, and Custom Axis, the only difference here is that as it is mentioned about we are not allowed to define both Rotate and Slide with the same Axis. When you go to define the Slide you will not see the Axis chosen in the Rotate option available. This is a common occurrence that can trip up users who believe that their Slide options are not consistent.


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PIN-SLOT JOINT

Planar Planar Joint allows the component to translate along two axes and rotate about a single axis. With the Planar Joint we allow motion along 2 translations as well as 1 rotation. The Planar Joint is great when we have two components that need to connect along the same plane, but not be constrained by limited additional degrees of freedom. A great example of this is when we need to move a box on top of a table. We can keep the bottom face of the box touching the top face of the table, but we are able to move the box along the table top and rotate the box about the normal of the table top. With Planar Joints we have the option to define the Normal and the Slide. With Normal we define which Axis is normal to our plane that we will rotate around. For Slide we are able to define the Axis we use for our planar movement. We are able to define the X, Y, Z, or Custom Axis for the normal, and the slide Axis will be deduced based off of our selection. For the Slide if we so choose we can also choose a Custom Axis.

PLANAR JOINT

Ball Ball Joint gives us the ability to rotate the component about all three axes using a gimbal system (three nested rotations). The Ball Joint gives us 3 available rotations, but no translations. The Ball Joint works great when as the name suggests we need to create a Ball Joint, or a Joint where full rotational freedom is required, but the rotate point should never move. With the Ball Joint we have the option to define the Pitch and Yaw. Pitch allows us to define the Lateral Axis we wish to use, whereas Yaw will allow us to define the Perpendicular axis. Pitch and Yaw are not able to use the same axis, and by defining these two options we also define our Roll or Longitudinal axis. We give this option so that you can define how you want to setup the


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orientation of your expected rotation and the values associated with the direction of the movement. Both Pitch and Yaw can be defined by a specific Axis or by a custom Axis. The manner in which you define these is similar to other Joint Types listed above.

BALL JOINT

Avoiding joint conflicts As we begin to create more joints, we may run into a scenario where we get a joint conflict. This is fairly common when we are trying to learn about joints. What this means is that the joint we are trying to create is attempting to limit degrees of freedom that are being left open by another joint. This can be caused by one of two scenarios.

First we have incorrectly selected a component. This is easily resolved by simply changing our component selection, and starting the joint again.

The other scenario is when we want to further limit our degrees of freedom and we are attempting to accomplish this with another Joint. The best way to approach this is instead to edit our existing joint and change our Joint Type to a more suitable Joint Type. Remember that the best practice when creating joints is to use the Joint Type that leaves the minimum number of degrees of freedom while giving the desired motion.


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JOINT CONFLICT ERROR

Editing Options When we right click on a joint from one of our access points we get a number of different options, many of which we will go into greater detail in this handout. While the creation of the joint may seem important, one of the most important pieces to fully leveraging your joints is taking advantage of the options in this menu.

RIGHT MOUSE BUTTON OPTIONS FOR JOINTS

Drive Joints Drive Joints allows us to define specific values for the different degrees of freedom allowed by the joint. We also are able to leverage the manipulator to quickly understand the motion.

Edit Joint Edit Joint gives us the ability edit the work we have already done with the Joint, it also proves as a way to change our component selections.

Edit Joint Limits Edit Joint Limits gives us the ability to edit and define the limits for our Joints. We will dive deeper into this area later in this handout.


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Lock Lock will lock the current values and location of the Joint. We are still able to edit the Joint and its limits, but the current position won’t change until we unlock the Joint. Lock also takes away our ability to drag the Joint.

Suppress Suppress gives us the ability to temporarily remove the Joint from performing its action. The Joint will act as though it has been deleted, and it won’t drive any motion between components. We use this to help troubleshoot joint conflicts. Suppress can also be used when you need to understand the motion of other Joints, and we want to Suppress the Joint so that we keep its values, but temporarily stop it from acting.

Animate Joint Animate Joint will animate the Joint only, and does not take into account grounded, other joints and any external effects on the Joints. Animate Joint works great when you need to understand the movement of a single Joint

Animate Model Animate Model will animate the model as a whole and does take into account grounded, and other joints that effect your model. We use this to understand the relationship between multiple Joints.

Go to Home Position When we move a component that has a Joint assigned to it, we are moving it away from its “home” position or the position where the Joint was initially created related to the linked component. We are able to move the joint back to this position with Go to Home Position. We also have a similar command that allows us to redefine the Home Position with “Set as Home Position”.

Select Components Select Components will select the components that the Joint is linked to. This helps us understand what the joint is affecting. We will go into greater detail around this when we talk about optimizing Distributed Designs.

Joint Limits Joint Limits give us the ability to control the values that our joints are able to travel. By limiting these values we can simulate realistic motion with the definition of minimum and maximum values. Joint Limits are fairly straight forward when we set them up, and leverage a lot of the existing knowledge from our Joint Types section. Each change made in the Joint Limits also has a parameter assigned to it, so you can create expression based limits in a parametric model.

EDIT JOINT LIMITS ACCESS POINT


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EDIT JOINT LIMITS DIALOG

Motion In the motion section of our Joints Limits we are able to apply our limits to each available degree of freedom. Each Joint Type has a different configuration of motion that we are able to limit, and many times the motion is the same available options we have when we first configure the Joint upon creation. Do note that when you are making changes to Joint Limits that each motion option has a different set of values associated with it.

Minimum/Maximum With Minimum and Maximum we are able to define the minimum and maximum value allowed by the Joint’s motion that we have selected. Positive and negative values are based on the way the Joint is setup and created.

Rest We are able to leverage the Rest option to tell the Joint where its rest position will be at. This is helpful because we can check the motion of our design by dragging different components, but when we are done the Joint will return to their rest position. Another benefit of the Rest option is when we dive into animating models, without a rest position animating a model will leave components in their positon until they are acted upon by another component. With a Rest position we can have the component pull back to its resting position instead, this is seen when mimicking springs.

Flip/Animate Similar to the Joint creation dialog we also have the option to Flip and Animate the joint, these actions will take into account the changes you have defined in your Joint Limits dialog.


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Motion Link With Motion Link we are able to specify a relationship between the degrees of freedom of the selected joints. Traditionally we think of a motion between two different joints, but because we focus on the degrees of freedom we can also link a joint to itself, as long as it has more than one degree of freedom. Motion Links help us to coordinate the translation or rotation of joints when linked components move. An example of this would be having linked doors, when you move one door the other door will move as well. This link will persist when you drag a component or when you perform a motion study.

When we start the Motion Link command we first will select the joints we are working with. If we only select a single joint we have the option to “Link with the same Joint.” We then will choose a single degree of freedom from each joint we have selected, and define the ratio for the movement. The below image shows that when Rev2 rotates 360 degrees, Planar1 will Slide in the Y direction .033 ft. If we need to create multiple links, we will do that by using a new motion link for each degree of freedom that requires linking.

MOTION LINK DIALOG

Learn how to maximize your joint capabilities inside of a distributed design

Distributed designs and Joints In Fusion 360 we have the ability to insert one design into another, and maintain the associativity between the two. When the referencing design is modified we can easily update the file to show the changes that we have made. Distributed designs are important because it allows you to work together with other users and it reduces the strain on computing changes when changes occur.

We can start a distributed design by opening up a new design and saving it, or by opening up an existing design. We then go to the data panel on the left and right click on the design we wish to insert. Using Insert into Current Design we will create our linkage, and start our distributed design.

Important differences for Joints in a distributed designs When working in a distributed design, Joints and how we use them change a little. The first important piece to understand is distributed designs allow us to leverage data from existing designs. What we are currently unable to do though is make changes to those designs without editing those designs directly. This impacts joints because it means that joints created in our top


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level design won’t show up in our referenced designs. So what does this mean for Joints and how should we set them up going forward?

When we create joints we want to create them in the lowest level design that has our components in it. One way to think about this is if we are building a robot, we will create Joints to connect all of the arms, legs, body and head together in their own separate designs. We then reference all of these designs into a single design and use Joints to attach the arms, legs, and head to the body. This breaks up our Joints so that we create them in the least common denominator where our components are contained.

Joint Errors after updates Joint errors can and will occurring while you’re working on your design. Sometimes this is caused by not setting up our joints correctly, and other times it is because we have made a design change that requires an update to our joints.

MULTIPLE JOINT ERRORS

When we have an error in our Joint one of the first things we should do is investigate it right away. Too often I see errors scattered in a timeline and ignored, because there was an intent to come back to it later. We get these errors because we have had a change that resulted in a problem for our Joint. We can investigate the problem by taking a look at the errors shown. Sometimes we will see an error icon in the lower right, others the best way to approach it is to dive right into the timeline node that is problematic.

JOINT ERROR MESSAGE – CLICKING GIVES ADDITIONAL INFORMATION The error icon will give us additional information on what Fusion is having problems with, and potentially giving us recommendations, each error message can be different. When we dive into the joint node we can edit the joint and try to solve the problem there.

The most common problem I see is when we make changes to the component that results in a change to the location of the Joint Origin that we created. An example of this is when we create a Joint Origin based off of an edge that we later decide to fillet. I am not telling you to not use edges, but rather that this happens and not to worry. We can easily solve this by editing the joint node, and redefining our Component selection and Joint Origin location.


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While not all examples are this straight forward, many issues can be when you go through the process step by step. As you understand more about Joints, the amount of time it takes you to resolve them will quickly diminish.

Rigid Group Rigid Group is a great tool that allows us to optimize our model. We leverage Rigid Groups when we need to constrain multiple bodies, or components to each other that have no capability of movement relative to themselves. So instead of creating multiple Rigid Joints, we use Rigid Group to easily constrain multiple objects at once. With Rigid Groups we lock the relative position of the selected components. The components contained within the Rigid Group are then treated as a single object when moved or when joints are applied.

Rigid Group is also a great way to improve the performance of your model if you are trying to use multiple Rigid Joints to lock multiple components together.

WE LEVERAGE RIGID GROUP TO LOCK IN THE RELATIVE POSITION OF A LARGE PORTION OF OUR SUBWOOFER

Snapshots A common thing that I see when working with customers who are new to Joints is an abundance of Snapshots in their timeline. So we are going to go over a couple quick tips around Snapshots as I feel it is important to your model health, and it is sometimes because of our Joints that a Snapshot is triggered. Snapshots are important to Fusion because it tracks the position of components within your design, this is especially helpful with position based modeling techniques.


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When you move a component by dragging the component in the graphics window, or you alter the position of a component by pulling on the Joint arrows, Fusion goes into a pending snapshot state. This simply means that some of your components are in a position that is different than what Fusion has captured in the timeline. This can be resolved by capturing the position of your components in a snapshot. Leveraging the move command or editing a joint will not force a pending snapshot since these changes are captured in the timeline already. The current recommendation is to revert your snapshot before making explicit moves. This allows you to explore motion of your model, and then revert yourself back to a known state. You can then follow up with your changes with a joint or move command. Doing this will allow you to reduce any clutter in your timeline by getting rid of extra snapshots, and focusing on the explicit movement that your model needs.

Every time we create a joint we first check to see if you have any pending snapshots in your model. If you do we ask if you wish to continue in the previous position, or capture the current position. This allows us to create the Joint in a state where the position of your components in known.

CONTINUE REVERTS THE POSITION, WHEREAS CAPTURE GENERATES A SNAPSHOT

Tips and Tricks for Joints Here are a number of tips and tricks for how to leverage Joints in your design and what best practices we can use to optimize our design. This will help us when we create a joint with distributed designs and ones without.

Activate Component

CLICKING THE RADIO BUTTON NEXT TO THE COMPONENT WILL ACTIVATE THE COMPONENT


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Activate Component is a critical function to keeping our information in our individual components, such as sketches and bodies. This is also important in the way we create our Joints and Joint Origins because it allows us to make sure that what we create is contained within the desired components and not put into other components. To avoid any confusion of where our Joints are located it is recommended to activate the component of where you are looking to create your Joint or Joint Origin. Activate Component is covered in more detail in the class session CP9991: Fusion 360 Workflows for Design Success: Top Down Versus Bottom Up.

Component Color Cycling and Component Color Swatch Component Color Cycling is an option that applies a different color to each component to help visually differentiate between them. When we pair this together with the Component Color Swatch it allows us to see the colors of the components matched to the colors used in the browser and timeline. This is a major help when you need to have some colors to differentiate your components, without putting appearances on every component. Both of these options are toggles that make it quick and easy to change our choice.

COMPONENT COLOR CYCLING AND COMPONENT COLOR SWATCH

Select Components Select Component is the command you didn’t know existed, but wish you had. When we select a Joint we gain an option in the right mouse button menu that allows us to select the components associated with that specific joint. This will save a lot of time when you are working in a distributed design because we are able to dive quickly into the components associated with our Joints. When your design has potentially hundreds of Joints this is a massive time saver.


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THE COMMAND YOU WISH YOU KNEW EXISTED

Learn how to capitalize on Joint Origins and Contact Sets to create intelligent models

Joint Origins Joint Origins are a core aspect of how we create our Joints, so it is prudent that we understand them in greater detail. There are two different ways of creating Joint Origins, we can leverage pre-generated points derived from faces, edges, and sketches, or we can manually create our Joint Origins based on those pre-generated points.

Tip: When we create or define our Joint Origins one important tip is leverage the snap key to keep the focus on the face you’ve selected so that you can snap to points that may be hard to select. In Windows you can hold the (Control) key or Mac you can hold the (Command).

Automatically generated points When we start the Joint command we are shown the different pre-generated points as we hover over different faces, edges and sketches. We are able to snap to these points to create our first Joint Origin.

The way that we pre-generate these points is based on a couple different aspects. Faces have boundary segments and the face centroid. Each of these segments have vertices, midpoints, and circular boundary points. The face you select will define the direction the Joint Origin is setup, while the segments will help define the position. Edges can be selected by either focusing on the face or the edge itself. You will have similar points to snap to, but the orientation will be different.

With snap points we have different shapes that help you understand the type of snap point you are selecting, this primarily helps you understand the location you are snapping to. Dots are vertices, triangles are mid-point, plus are for circular centers, and a square denotes the face centroid.


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THE 4 DIFFERENT PRE-GENERATED TYPES OF POINTS TO JOINT ORIGIN CREATION

Manual Creation Now you may come across a scenario where the automatically generated points for your Joint Origin may not be good enough. We can always create a sketch and make sure that it is in the correct component and take the time to create a sketch entity to use for our Joint Origin. A better way to approach this is with our Joint Origin command. With the Joint Origin command we can create our own Joint Origin to use for our Joints. We start by leveraging the pre-generated points and from there we can define the location. We are able to control the Angle, the Offset in the X, Y, and Z directions, Flip and Reorient the axis. This gives our Joint Origin creation a lot of power to help us define our connection points.

Manually creating Joints, while not always necessary is a huge timer saver, and adds a lot of power to our Joints system.


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JOINT ORIGIN DIALOG

Contact Sets Contact Sets constrain components so that they cannot pass through each other, and thus behave as they would in the real world. Contact Sets allow us to constrain specific components together without constraining the entire model. We do this so we can understand specific areas of the model and how joints and motion act when the components interact. We have the ability to create multiple contact sets and turn on and off different sets.

If we so choose, we have the ability to Enable All Contact for all of the components in our model. This can be a great way to understand the motion and interactions of your entire model. The more components and interactions you have the more consumption is required from the application.

When not to use Contact Sets Contact Sets are very powerful, but when your design starts to grow, it is very easy to overload Fusion’s compute solver. If you start to notice a performance degradation in your design, it is recommended to leave Contact Sets off. Contact sets are great, but once you understand your motion, it is best to use Joint Limits to simulate the motion and constraints associated with your components. This will help the performance of your design and give you the ability to constantly keep your limits on.

Learn how to use joints to create animations and motion studies.

Taking our Joints to the next level We have spent all of this time working through how to create our Joints and how best to implement them, it is only natural that we find ways to extend them even further.

Animations The Animations environment is a great way for us to showcase our designs and create videos of our motion. While in the animations environment we leverage the Transform Components


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command to define the movement at different time steps for our components. While we are not able to have our joints translate into this environment, many of our principles for constructing our joints are applicable.

The Transform Components command allows us to define a value for each degree of freedom for the component. We can then use Set Pivot to set the pivot point to act as our Joint Origin and move the component. An important note when setting your pivot point is to make sure you complete the setting of your pivot point before attempting to move your model. This will help reduce any confusion on why your components are not moving as expected. Lastly the Transform Component selects at the component level by default in the graphics window. When using subcomponents you can select from the browser to select a higher level component that may contain multiple components.

Motion Study In Fusion 360 we leverage motion studies to help us simulate motion in a design. When we start a Motion Study we choose our Joints that we wish to study. Doing so will show us all of the available degrees of freedom for our selected Joints.

We can now step to each time frame that we wish and define a value for each degree of freedom. Doing this multiple times will give us our expected motion. We can now watch multiple Joints be driven and see how the rest of our model reacts. This is the nature of our Motion Study, understanding how our model will respond to movement in one or multiple Joints over a period of time.

We have the ability to play through the timeline forwards and backwards, loop the motion, and control the speed of the playback.

MOTION STUDY EXAMPLE

cp10165 joints, so much more than just rigid

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