--- title: "Build a hinged door" url: /docs/en-us/tutorials/use-case-tutorials/physics/build-a-hinged-door last_updated: 2026-06-11T23:12:04Z description: "The process for creating a door using a HingeConstraint." --- # Build a hinged door Roblox's physics system allows you to construct moving mechanisms like doors, rotating platforms, and even vehicles using **constraints**. For instance, a swinging door can be built using the `Class.HingeConstraint`. ## Door setup Start by creating parts for the door and its attachments. **Attachments** are where one object can connect to another. These attachments will later be used to connect the door to its frame with a hinge. 1. Create two parts with names like **Door** and **DoorFrame**.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints-showDoorCreated.jpg) 2. Select **DoorFrame**. In the **Properties** window, enable **Anchored** so it won't move.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_selectAnchored.png) 3. In the **Explorer**, hover over **DoorFrame** and add a new **Attachment**. Repeat the same to add an attachment to the **Door**.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_attachmentsCreated.png) 4. Rename the attachments to indicate what they're attached to, such as **DoorAttachment** and **FrameAttachment**.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_attachmentsRenamed.png) ## Move the attachments New attachments are created in the center of a part. So they can work with the door, the two attachments need to be moved to face each other. 1. To view constraints and attachments, toggle on **Show Constraint Details** from Studio's **View** menu. 2. In the **Explorer**, select **FrameAttachment**.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_selectFrameAttachment.png) 3. Press `F` to focus on the attachment and zoom in if needed. Then, use the **Move** tool to position the attachment on the surface of the door frame, facing the door. > **Info:** It's best to position attachments so they're precisely aligned with one another. In this case, misaligned attachments may cause the door to swing incorrectly. > > For precise positioning, use **Snap to Grid** with increments appropriate for the size of the part. Alternatively, edit the attachment's position in the **Properties** window. 4. Repeat the same to move **DoorAttachment**. Your attachments should be positioned on the surface facing their counterpart. _**Left**: FrameAttachment / **Right**: DoorAttachment_ ## Rotate the attachments The orientation of an attachment affects how a constraint can move. For the door, both attachments must be rotated so the hinge swings left and right, like those on a standard door. 1. On the door frame, hover over **FrameAttachment**. Notice the **yellow arrow**. This arrow, the **axis**, determines the hinge's rotation.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_showAttachmentAxis.jpg) > **Info:** Depending on the **DoorFrame** object, the axis may point in a different direction. For instance, a hinge added to the attachment shown above would pivot around the yellow arrow, like in the video below. 2. For accurate rotation, turn on rotation snapping in Studio's toolbar by checking **Rotate** and setting the value to `90`.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_snapRotate.png) 3. Use the **Rotate** tool to orient **both** yellow attachments to point **upwards**. If your axes are already vertical, no action is needed.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_primaryAxis.jpg) ## Add the constraint Remember, constraints are a way of connecting two attachments to move in a specific way. This door will use a `Class.HingeConstraint`, a common constraint that rotates objects along the axes of two attachments. 1. Under **DoorFrame**, create a new **HingeConstraint**.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_showCreateHingeConstraint.png) 2. In the constraint's properties, find **Attachment0**. Click the empty box right of the property and then, in the **Explorer**, click **DoorAttachment**. 3. Repeat the same process by connecting **Attachment1** to **FrameAttachment**. The properties should appear as below.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_attachmentsConnected.png) 4. Test the project by walking into the door with your character. > **Warning:** You may encounter the following issues when testing: > > **Parts not moving:** - Make sure that your door is not anchored. - Make sure that the door's motion isn't blocked by terrain or nearby parts. > > **Door not swinging as expected:** - Ensure the axis of each attachment is pointed up (see [Rotating Attachments](#rotate-the-attachments)). ## Adjust the door The door is currently able to swing past the door frame. This can be fixed by adjusting the hinge **limits**. 1. In the properties for **HingeConstraint**, find and toggle **LimitsEnabled**. When active, you can set the rotation limits of the hinge.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_limitsEnabled.png) 2. To make sure this is oriented correctly, select **DoorAttachment** and use the rotate tool so the orange arrow points **towards** the door frame, like below.![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_secondaryAxisArrow.png) > **Warning:** Remember that the yellow axis arrows affect the pivot of the hinge. Limits are affected by the orange axis arrows. 3. Under the **Limits** section of the properties, both LowerAngle and UpperAngle to -90 and 90, respectively. This creates a range of motion like the image on the left. 4. Test the door and notice that the hinge is now limited. > **Warning:** If the door limits don't work as expected, it's possible that the orange axis on an attachment isn't correctly aligned. Select DoorAttachment, and make sure that a green plane with an arc points **towards** the door frame, as in the image below. > > ![alt](../../../assets/tutorials/building-a-hinged-door/introToConstraints_showAxisArc.jpg) With the door complete, take some time to explore using hinge constraints in different situations, such as a trap door or a swinging axe trap.