In this Blender tutorial I will show you how to use drivers to animate gears in Blender.
Gears
To quickly add gears to the scene make sure you have the “Add Mesh: Extra Objects” addon activated in your preferences
In top view, add a gear to the scene
In the gear options, change the number of teeth to 24 and leave the radius at 1 meter – this will help us determine the size and number of teeth for the other gears
Add a second gear with 12 teeth and change the radius to 0.5 – this will be the smallest gear
We need a gear with half the radius and half the number of teeth to properly rotate along with the first gear we made
Move the smaller gear along the X- and Y-Axis and align it with the first gear
Add a third gear with 48 teeth and change the radius to 2 – this will be the largest gear
We need a gear with twice the radius and with twice the number of teeth to properly rotate along with the first gear we made
Move the larger gear along the X- and Y-Axis and align it with the first gear
Drivers (1)
Split the viewport and open the drivers editor
Select the smallest gear and open the properties panel (N)
Under the item tab, right-click on the Z-rotation field and choose “add driver”
In the drivers editor, select the added driver and use the N-key to open the properties panel
On the drivers tab, for the expression, write –(var*2) – it must be negative so it rotates in the correct direction
Change the location type to Z rotation
Select the first gear for the object and click on “update dependencies”
When you select the first gear and rotate it around the Z-Axis, both gears should move
The smallest gear should rotate twice for every one-time the larger gear rotates
Drivers (2)
Select the largest gear and right-click on the Z-rotation field and choose “add driver”
In the drivers editor, select the added driver
On the drivers tab, for the expression, write –(var/2) – it needs to be divided since it is twice as large as the middle gear
Change the location type to Z rotation
Select the first gear for the object and click on “update dependencies”
When you select the first gear and rotate it around the Z-Axis, all three gears should move
The middle gear should rotate twice for every one-time the largest gear rotates