I’ve tried absolutely everything I can think of with this and it still will not work. So I’m hoping someone will know how to fix it. All I’m trying to do is get a ball to roll down a ramp, nothing complicated. When you run the engine all it does is bounce off some invisible bounds that cannot be seen.
Here’s the file:
http://www.blending-online.co.uk/Ballercoaster3.zip
Suggestions anyone?
Have you tried turning off bounds and just using the default bounding sphere?
Sometimes a bounding option requires a lot of space between the object and the static geometry.
Just leave bounds off for the ramp too, it will have per-face collision by default.
Tried this, no effect 
http://blenderartists.org/forum/showthread.php?t=85562
Pretty much the same issue, you just have to increase the overall scale of everything.
When I made the objects bigger, it worked just fine.
Trying to help people, could be a hard job sometimes…30 mn to solve this one
Please, read and follow the “basics”
You’re are working on a too small scale
In the view properties Set spacing to 1
Then add a cube or sphere
Then scale your objects according to the new ones
Then Apply Scale and rotation to both Ctrl-A keys
Then set the sphere size Radius: to 1
Should work now
Thanks everyone. Yes the problem was that the object was too small. Sumo handled objects of this size without any issues so I assumed Bullet would do the same… (kind of ironic having a name like Bullet yet not being able to handle bullet sized objects :p)
–there are bullet tips on the wiki that tell you what scale to use… all physics engines use calculations based on scale… if your objects are to small (as in millimeters long) it’s not going to work… if they are too big it’s not going to work (as in kilometers long) .This has been talked about quite a lot recently on this forum…