Well, I was trying to make some cogs spin using the game engine, you know like the ones you see in clocks, but they don’t interact properly. What am I doing wrong?
http://files-upload.com/files/622454/cogs.blend
Thanks in advance
Hello
“What am I doing wrong?”
all! 
Some tips:
add a cylinder as main body.
Make it Actor - Dynamic - RigidBody
Bounds - Cylinder - Compound
Add a “Hinge” constraint ( the pivot and Ax depends on how your object is placed, make some tries)
Now add cubes as teeth’s
Each teeth will be an Actor - Dynamic - Rigid Body, parented to the main body
When done you can duplicate the whole group to make other gears
Select the the cylinder gear that will lead the others and give him some angular velocity:
Always Sensor -> AND -> Motion Actuator - Ang V -x, Y , or Z value
Now try the magic P key…should work…I hope
Bye
Where is this hinge constraint located?
Object buttons window ( F7), Constraint Panel, ADD Constraint - Rigid Body joint
Some docs reading, maybe?
If you made each gear a single object, it would have to be concave. That could be why it didn’t work well.