NORMAL AND TANGENTIAL COMPONENTS (Section 12.7) When a particle moves along a curved path, it is sometimes convenient to describe its motion using coordinates other than Cartesian. When the path of motion is known, normal (n) and tangential (t) coordinates are often used. In the n-t coordinate system, the origin is located on the particle.
This functionality is available on Onshape's browser, iOS, and Android platforms.
Mates in Onshape are different than mates in old CAD systems. There is only one Onshape Mate between any two instances, and the movement (degrees of freedom) between those two instances is embedded in the Mate. Mates contain their own coordinate systems, so you ever only need to use one Mate to define the degrees of freedom between two entities. At the time of placing a mate between two entities, Onshape will offer points on each entity to which to align with the mate's coordinate system. The suggested locations are based on the underlying geometry of the part and changing the geometry will change the location of the mate. This can be undesirable in certain situations, but you can also:
Shortcut: m
Use the shortcut key j to hide/show mates in an assembly.
Note that you are able to mate entities to the Origin in an Assembly. You are also able to Fix an entity in order to test the movement of assigned Mates using the context menu or drag.
Entities include: parts, assemblies, subassemblies, sketches, and surfaces.
Mates are defined through the Mate dialog:
You select the type of mate to create, then select the mate connectors (one for each part). You are also able to check the box to apply limits of movement. Other options/action include:
Many mates offer the ability to set an Offset distance for defining a fixed space between the parts being mated, as well as distance Limits for movement.
Limits are visualized in the graphics area as dashed lines with bars at the ends. The dashed lines represent the direction and distance of the movement and the solid lines represent the limit.Offset distances are visualized in the graphics area as dashed lines between the Mates, displaying the value and the axis. Enter the distance in the dialog.
When you click on a Mate, graphics are displayed to indicate the direction of the X, Y, and Z as defined by the Mate along the with the offset and the range of limits dimensions (if any).
Applying an offset should be viewed as moving the entire coordinate system. The offset is relative to the Mate connector selected first.
When the Offset box is checked, many mates also offer an option to specify rotation about a specific axis: Slider, Revolute, Pin Slot, Planar, and Fastened mates include the option, as see below:
Select the axis about which to rotate, above, then enter the degrees of rotation
When you open a Mate dialog and select two Mate connectors, a head-up display appears at your cursor:
Click the checkmark in the head-up display to commit the current mate and start a new Mate. The Mate dialog box stays open, and you are free to continue selecting Mates.
Offset distances are visualized in the graphics area as dashed lines between the Mates, with editable values. Drag the part to a desired position, double-click the distance value and enter a new value. These values are not persisted; you are able to use them to estimate values to enter in the Offset field in the dialog, or place parts in precise positions in order to take measurements. For example:
Mate values for axes and rotational movement (above).
Mate value in edit (above).
Mate context menuUse the Mate context menu to access the following commands:
Once a Mate is created and listed in the Mate Features list, select a Mate (or Ctrl-click to select more than one) and drag/drop to reorder them in the list. This will help put the most important mate features higher and more visible in the list. Onshape solves mates simultaneously so order won't affect a Mate.
You have the ability to specify Mate values of all mates except Ball, Fastened, and Tangent. Onshape provides visual cues for distances, and provides distance values, in default units, from the second Mate connector selected to the first. Specify limits in positive and negative values.
In this example, the Mate connector on the box was the first one selected in the dialog; the Mate connector on the cylinder was the second selected. Notice that the Y value is negative and the X value is positive.
Now, switch the order of Mate connector selection and notice the distance values:
Notice that in this scenario, the Y value is positive and the X value is positive. This is due to the order of measurement from one Mate connector to the other. It's important to remember that the measurement is made from the second selected Mate connector to the first, along the coordinate system.
Use these distance visualizations to estimate the value to enter in the Limits box:
You are able to use expressions and trigonometric functions in numeric fields in Assemblies.
Use the Animate command (found in the context menu for mates and mate indicators) to drive the assembly from a single Mate (or single DOF within a Mate). Other Mates and relations in the assembly are also enforced and honored.
If you have defined limits for the Mate, those values are used as the start and stop points during the animation.
Note that you are able to enter up to 36000 degrees here (100 revolutions), specifically helpful for visualizing degrees of freedom in high-ratio gears and rack and pinion relations.
Current value is a read-only field and is populated during animation as the Mate moves through the degrees of freedom, in your specified units. When the motion stops (either automatically or manually), Current value displays the point at which the motion was stopped.
Animate supports all Mate types but it’s not recommended to use Fastened, Tangent, or Ball as the driving mate.
Offsetting entities from one another during assembly is available for the following Mate types:
You are also able to drag the entities and observe the distance values in the graphics area. These will help determine the specific values to enter in the dialog.
You are able to use expressions and trigonometric functions in numeric fields in Assemblies.
Copying/Pasting assembled entitiesYou are able to copy and paste entities that have been mated in an Assembly:
The entities are pasted directly where the mouse click occurs.
Notice that the entities, mate connectors, and mates are also duplicated in the Assembly list.
Mate indicatorsIn addition to being visible in the Assembly list, mates have indicators in the graphics area as well. You have the ability to hide the entities and mate connectors in the Assembly list in order to see these mate indicators more clearly. These indicators give hints at the type of motion they define as well as the current state: blue/white indicates good Mates, gray indicates suppressed or inactive, and red indicates a problem:
Fastened
Revolute
Slider
Planar
Cylindrical
Pin slot, with an arrow in the direction of the slot
Ball
Tangent
Parallel
Group
More tips for visualizing Mates:
Before Mate | After Mate |
The Mate type then specifies the degrees of freedom behavior.
ExampleIn the example above, only automatic Mate connectors were used. In most mating cases, automatic Mate connectors will work fine. In some less common cases, it may be useful to create Mate connectors ahead of time. You have the ability to create Mate connectors in either the Assembly or in the Part Studio.
Mates: iOSMates in Onshape are different than mates in traditional CAD systems. There is only one Onshape Mate between any two instances, and the movement (degrees of freedom) between those two instances is embedded in the Mate.
Note that you are able to mate an entity to the Origin in an Assembly. You are also able to Fix an entity, in order to test the movement of assigned Mates, using the context menu. Entities include: parts, assemblies, subassemblies, sketches, and surfaces.
Mate dialogMates are defined through the Mate dialog:
Select the type of Mate to create, then select the Mate connectors (one for each part).
Mate type - The Mate type field displays the type of Mate you are using. Tap to open a list of Mate types and tap to select one.
Mate connectors - The next section, Mate connectors, is highlighted in blue. This indicates that a selection from the graphics area is required. Two Mate connectors (one from each instance being mated) must be selected.
Offset - Tap to set an offset distance for defining a fixed space between the parts being mated.
Limits - Tap to set distance limits for movement.
- Flip the primary axis, Z orientation of the instances.
- Reorient the secondary axis; rotate the quadrant orientation (in the XY plane) of the instances by 90 degrees at a tap.
Solve - Tap to solve all assembly Mates including the current one.
You have the ability to specify movement limits of all Mates except Ball, Fastened, and Tangent.
Inside the dialog of a Mate that allows limits (Revolute, Slider, Planar, Cylindrical, and Pin slot) toggle the Limits button on and limit fields appear.
Enter desired limit specifications and tap Solve to visualize the changes.
Offset entities during assemblyOffsetting entities from one another during assembly is available for the following Mate types:
You are also able to drag the entities and observe the distance values in the graphics area. These will help determine the specific values to enter in the dialog.
You are able to use expressions and trigonometric functions in numeric fields in Assemblies.
Mate indicatorsIn addition to being visible in the Assembly list, Mates have indicators in the graphics area as well. You are able to hide the entities and Mate connectors in the Assembly list in order to see these Mate indicators more clearly. These indicators give hints at the type of motion they define as well as the current state: blue/white indicates good Mates, gray indicates suppressed or inactive, and red indicates a problem.
Fastened
Revolute
Slider
Planar
Cylindrical
Pin slot, with an arrow in the direction of the slot
Ball
Tangent
Parallel
Group
More tips for visualizing Mates:
Before Mate
After Mate
The Flip primary axis tool flips the major (Z) orientation.
The Reorient secondary axis tool adjusts the orientation in 90 degree increments.
The Mate type specifies the movement behavior.
Mates: AndroidMates in Onshape are different than mates in traditional CAD systems. There is only one Onshape Mate between any two instances, and the movement (degrees of freedom) between those two instances is embedded in the Mate.
Note that you are able to mate an entity to the Origin in an Assembly. You are also able to Fix an entity, in order to test the movement of assigned Mates, using the context menu. Entities include: parts, assemblies, subassemblies, sketches, and surfaces.
Mate dialogMates are defined through the Mate dialog:
Select the type of Mate to create, then select the Mate connectors, inferred or existing (one for each part).
Mate type - The Mate type field displays the type of Mate you are using. Tap to open a list of Mate types and tap to select one.
Mate connectors - The next section, Mate connectors, is highlighted in blue. This indicates that a selection from the graphics area is required. Two Mate connectors (one from each instance being mated) must be selected.
Offset - Tap to set an offset distance for defining a fixed space between the parts being mated.
Limits - Tap to set distance limits for movement.
- Flip the primary axis, Z orientation of the instances.
- Reorient the secondary axis; rotate the quadrant orientation (in the XY plane) of the instances by 90 degrees at a tap.
Solve - Tap to solve all assembly Mates including the current one.
You are able to specify movement limits of all Mates except Ball, Fastened, and Tangent.
Inside the dialog of a Mate that allows limits (Revolute, Slider, Planar, Cylindrical, and Pin slot) toggle the Limits button on and limit fields appear.
Enter desired limit specifications and tap Solve to visualize the changes.
Offset entities during assemblyOffsetting entities from one another during assembly is available for the following Mate types:
You are also able to drag the entities and observe the distance values in the graphics area. These will help determine the specific values to enter in the dialog.
You are able to use expressions and trigonometric functions in numeric fields in Assemblies.
Mate indicatorsIn addition to being visible in the Assembly list, Mates have indicators in the graphics area as well. You have the ability to hide the entities and Mate connectors in the Assembly list in order to see these Mate indicators more clearly. These indicators give hints at the type of motion they define as well as the current state: blue/white indicates good Mates, gray indicates suppressed or inactive, and red indicates a problem.
Fastened
Revolute
Slider
Planar
Cylindrical
Pin slot, with an arrow in the direction of the slot
Ball
Tangent
Parallel
Group
More tips for visualizing Mates:
Before Mate
After Mate
The Flip primary axis tool flips the major (Z) orientation.
The Reorient secondary axis tool adjusts the orientation in 90 degree increments.
The Mate type specifies the movement behavior.
Was this article helpful?