When the shape in the "collisions" drop-down menu of my sphere's rigid body settings is set to "sphere" It just drops onto one of the cylinders and stays there perfectly still after the fall. However, it slides off okay when it's set to "convex hull"
Does anybody know what is happening, and whether it should happen?
Hi
SnowChickenFlake ,
The only thing I can think of (without actually seeing your .blend file) is, that your Origin is not exactly in the center of your Sphere.
The Sphere Collision is a sphere around the Origin of the Object (in this case a Sphere). The Convex Hull makes a sphere around the Sphere Mesh, no matter where the Origin is:
Man, this is hard to explain in words; this exaggerated image might help a bit (hopefully):

But this is just a guess, so if it's not this, I would need to see your .blend. (Upload your file to Googledrive or dropbox or so and post a link here)
Sorry, but I can't seem to replicate the issue. Maybe it was an error on my part. Either way, I appreciate the help