Many contraptions in Roblox will use multiple constraints to build more complicated mechanisms. In particular, you can configure several constraints to be actuated, meaning they will move under their own power. This tutorial will show you how to actuate a HingeConstraint to be a motor in order to make a ferris wheel.
Ferris Wheel Setup
Add a ferris wheel into a place using either this model or this pre-built place.
To view constraints and attachments, in the Model tab, toggle on Constraint Details.
Add Attachments
You will need to add attachments to the ferris wheel to determine where it will rotate. When working with attachments, it helps to move the pieces you are working with apart so you can clearly see the position and orientation of the attachments.
In the Explorer, expand FerrisWheel, select the MainSupport model, and move it so you can see the side of the wheel axle as well as the side of the support axle.
Expand MainSupport and select SupportAxle. Insert an attachment and rename it SupportAttachment.
Move SupportAttachment so that it is on the inside edge of the SupportAxle.
In the FerrisWheel, select WheelAxle and add a new attachment named WheelAttachment.
Move the WheelAttachment to the edge of the axle. Make sure this is the side facing the support where you placed the SupportAttachment.
If you hover over the attachments, you'll see yellow and orange arrows appear. Make sure the yellow arrows for both attachments are pointing in the same direction. If they aren't, use the Rotate tool to make sure they are pointed the same way.
Creating a HingeConstraint
Now that both attachments are in place, it's time to add a HingeConstraint to act as the motor for the wheel.
In the SupportAxle, create a new HingeConstraint and name it MainMotor.
In the properties of MainMotor, set Attachment0 to SupportAttachment, and Attachment1 to WheelAttachment.
Select the MainSupport model and return it to its original position.
Changing to Motor
By default, HingeConstraints will only turn if an outside force acts on them, such as a user character pushing in the connected parts. To make a HingeConstraint turn on its own, we have to configure it to be a Motor, set our desired turn rate, and make sure the hinge has enough torque.
Select MainMotor and, in the properties, change ActuatorType to Motor.
Change AngularVelocity to 0.314.
The AngularVelocity property uses radians per second to set how fast its motor turns. Radians are a unit used to measure angles. Most radian values are based on pi, which is approximately 3.14. If you want to precisely configure how quickly or slowly your hinge turns, trying some values related to pi is a good starting point.
- 1 revolution per second = 2 * pi = 6.28
- ½ revolution per second = pi = 3.14
- ¼ revolution per second = pi / 2 = 1.57
- 1/10 revolution per second = pi / 10 = .314
Copy the inf value from MotorMaxAcceleration to MotorMaxTorque so that the wheel can handle any amount of weight.
Test your wheel turning behavior by selecting Play and testing your experience.
Notice that you only need the motor on one side of the wheel; you do not need motors on both sides. When building with contraptions, try using as few constraints as possible. This ensures that your contraptions are stable and reliable.
Now that you have the ferris wheel fully built, try experimenting with more constraints. You can add more cars to the ferris wheel, or you can try building an original contraption.