Source: Roblox Creator Hub · CC BY 4.0 · View source · Code samples: MIT Imported 2026-10-03. Formatting adapted for this site.
JointInstance
Inherits from: Instance → Object
JointInstance is the base class for joints such as Welds and Motors.
Weld, WeldConstraint, Motor, and Motor6D all combine multiple parts into the same assembly. Every assembly has a root part (BasePart:GetRootPart()) and when C0/C1 of a JointInstance is modified, the root part will stay where it was.
Welds do not have any directionality. You can imagine rigid joints forming a tree branching down from the root part. All the parts down the tree from root will move, and their welded "children" in this tree will move with them.
Inherits from: Instance
Descendants: DynamicRotate, Glue, ManualSurfaceJointInstance, Motor, Rotate, Snap, VelocityMotor, Weld
Memory category: BaseParts
Tags: NotCreatable
Properties
| Name | Type / Returns | Description |
|---|---|---|
| JointInstance.Active | boolean | Determines if the joint is currently active in the world. |
| JointInstance.C0 | CFrame | Determines how the offset point is attached to JointInstance.Part0. |
| JointInstance.C1 | CFrame | Subtracted from the C0 property to create an offset point for Part1. |
| JointInstance.Enabled | boolean | Sets whether the joint is active or not. |
| JointInstance.Part0 | BasePart | The first BasePart that the joint connects. |
| JointInstance.Part1 | BasePart | The second BasePart that the joint connects. |
| JointInstance.part1 | BasePart |
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance.Archivable | boolean | Determines if an Instance and its descendants can be cloned using Instance:Clone(), and can be saved/published. |
| Instance.archivable | boolean | |
| Instance.Capabilities | SecurityCapabilities | The set of capabilities allowed to be used for scripts inside this container. |
| Instance.IsInSandbox | boolean | Indicates whether the instance is inside a sandboxed container. |
| Instance.Name | string | A non-unique identifier of the Instance. |
| Instance.Parent | Instance | Determines the hierarchical parent of the Instance. |
| Instance.PredictionMode | PredictionMode | Reflects the client-side prediction mode applied to the instance under server-authoritative physics. |
| Instance.RobloxLocked | boolean | A deprecated property that used to protect CoreGui objects. |
| Instance.Sandboxed | boolean | When enabled, the instance can only access abilities in its Capabilities list. |
| Instance.UniqueId | UniqueId | A unique identifier for the instance. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object.ClassName | string | A read-only string representing the class this Object belongs to. |
| Object.className | string |
JointInstance.Active
This property determines if the joint is currently active in the world.
If the JointInstance is not in Workspace or JointsService, or one of its parts is not in Workspace, the joint will be inactive.
Rigid joints like Weld, Snap, WeldConstraint, Motor, or Motor6D may also be disabled due to conflicts with other rigid joints, such as joints between the same two parts or indirect cycles in the weld graph. Joints disabled this way may be re-enabled later when another joint or part is added or removed.
| Field | Value |
|---|---|
| type | boolean |
| tags | ["ReadOnly","NotReplicated"] |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Behavior |
| serialization | {"can_load":false,"can_save":false} |
| capabilities | ["Physics"] |
JointInstance.C0
C0 is the position aspect of the orientation between two parts in a weld. Part0 and Part1 move accordingly to this value, which denotes their respective positions.
When animating a Motor6D, it's recommended to tween its Transform property instead of C0.
| Field | Value |
|---|---|
| type | CFrame |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Data |
| serialization | {"can_load":true,"can_save":true} |
| capabilities | ["Physics"] |
JointInstance.C1
This property is subtracted from the C0 property to create an offset point for Part1.
When animating a Motor6D, it's recommended to tween its Transform property instead of C1.
| Field | Value |
|---|---|
| type | CFrame |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Data |
| serialization | {"can_load":true,"can_save":true} |
| capabilities | ["Physics"] |
JointInstance.Enabled
This property sets whether the joint is active or not.
When this property is set to true and the joint's Part0 and Part1 properties are set, the joint will ensure that its two parts will be connected and behave according to joint type.
See also Active which determines if the joint is currently active in the world.
| Field | Value |
|---|---|
| type | boolean |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Behavior |
| serialization | {"can_load":true,"can_save":true} |
| capabilities | ["Physics"] |
JointInstance.Part0
This property indicates the first BasePart that the joint connects.
| Field | Value |
|---|---|
| type | BasePart |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Data |
| serialization | {"can_load":true,"can_save":true} |
| capabilities | ["Physics"] |
JointInstance.Part1
This property indicates the second BasePart that the joint connects.
| Field | Value |
|---|---|
| type | BasePart |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Data |
| serialization | {"can_load":true,"can_save":true} |
| capabilities | ["Physics"] |
JointInstance.part1
Deprecated. This deprecated property is a variant of Part1 which should be used instead.
| Field | Value |
|---|---|
| type | BasePart |
| tags | ["Hidden","NotReplicated","Deprecated"] |
| security | {"read":"None","write":"None"} |
| thread safety | ReadSafe |
| category | Data |
| serialization | {"can_load":false,"can_save":false} |
| capabilities | ["Physics"] |
Methods
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance:AddTag | () | Applies a tag to the instance. |
| Instance:children | Instances | Returns an array of the object's children. |
| Instance:ClearAllChildren | () | This method destroys all of an instance's children. |
| Instance:Clone | Instance | Create a copy of an instance and all its descendants, ignoring instances that are not Archivable. |
| Instance:clone | Instance | |
| Instance:Destroy | () | Sets the Instance.Parent property to nil, locks the Instance.Parent property, disconnects all connections, and calls Destroy() on all children. |
| Instance:destroy | () | |
| Instance:FindFirstAncestor | Instance? | Returns the first ancestor of the Instance whose Instance.Name is equal to the given name. |
| Instance:FindFirstAncestorOfClass | Instance? | Returns the first ancestor of the Instance whose Object.ClassName is equal to the given className. |
| Instance:FindFirstAncestorWhichIsA | Instance? | Returns the first ancestor of the Instance for whom Object:IsA() returns true for the given className. |
| Instance:FindFirstChild | Instance? | Returns the first child of the Instance found with the given name. |
| Instance:findFirstChild | Instance | |
| Instance:FindFirstChildOfClass | Instance? | Returns the first child of the Instance whose ClassName is equal to the given class name. |
| Instance:FindFirstChildWhichIsA | Instance? | Returns the first child of the Instance for whom Object:IsA() returns true for the given className. |
| Instance:FindFirstDescendant | Instance? | Returns the first descendant found with the given Instance.Name. |
| Instance:GetActor | Actor? | Returns the Actor associated with the Instance, if any. |
| Instance:GetAttribute | Variant | Returns the value which has been assigned to the given attribute name. |
| Instance:GetAttributeChangedSignal | RBXScriptSignal | Returns an event that fires when the given attribute changes. |
| Instance:GetAttributes | Dictionary | Returns a dictionary of the instance's attributes. |
| Instance:GetChildren | Instances | Returns an array containing all of the instance's children. |
| Instance:getChildren | Instances | |
| Instance:GetDebugId | string | Returns a coded string of the debug ID used internally by Roblox. |
| Instance:GetDescendants | Instances | Returns an array containing all of the descendants of the instance. |
| Instance:GetFullName | string | Returns a string describing the instance's ancestry. |
| Instance:GetStyled | Variant | Returns the styled or explicitly modified value of the specified property, or else the default property value if it hasn't been styled/modified. |
| Instance:GetStyledPropertyChangedSignal | RBXScriptSignal | Returns an event that fires when the given style property changes on the instance. |
| Instance:GetTags | Array | Gets an array of all tags applied to the instance. |
| Instance:HasTag | boolean | Check whether the instance has a given tag. |
| Instance:IsAncestorOf | boolean | Returns true if an Instance is an ancestor of the given descendant. |
| Instance:IsDescendantOf | boolean | Returns true if an Instance is a descendant of the given ancestor. |
| Instance:isDescendantOf | boolean | |
| Instance:IsPropertyModified | boolean | Returns true if the value stored in the specified property is not equal to the code-instantiated default. |
| Instance:QueryDescendants | Instances | Returns an array containing all descendants of the instance that match the selector string. |
| Instance:Remove | () | Sets the object's Parent to nil, and does the same for all its descendants. |
| Instance:remove | () | |
| Instance:RemoveTag | () | Removes a tag from the instance. |
| Instance:ResetPropertyToDefault | () | Resets a property to its default value. |
| Instance:SetAttribute | () | Sets the attribute with the given name to the given value. |
| Instance:WaitForChild | Instance | Returns the child of the Instance with the given name. If the child does not exist, it will yield the current thread until it does. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object:GetPropertyChangedSignal | RBXScriptSignal | Get an event that fires when a given property of the object changes. |
| Object:IsA | boolean | Returns true if an object's class matches or inherits from a given class. |
| Object:isA | boolean |
Events
Inherited from Instance
| Name | Type / Returns | Description |
|---|---|---|
| Instance.AncestryChanged | Fires when the Instance.Parent property of this object or one of its ancestors is changed. | |
| Instance.AttributeChanged | Fires whenever an attribute is changed on the Instance. | |
| Instance.ChildAdded | Fires after an object is parented to this Instance. | |
| Instance.childAdded | ||
| Instance.ChildRemoved | Fires after a child is removed from this Instance. | |
| Instance.DescendantAdded | Fires after a descendant is added to the Instance. | |
| Instance.DescendantRemoving | Fires immediately before a descendant of the Instance is removed. | |
| Instance.Destroying | Fires immediately before (or is deferred until after) the instance is destroyed via Instance:Destroy(). | |
| Instance.StyledPropertiesChanged | Fires whenever any style property is changed on the instance, including when a property is set to nil. |
Inherited from Object
| Name | Type / Returns | Description |
|---|---|---|
| Object.Changed | Fires immediately after a property of the object changes, with some limitations. |