I have a scene with a tall stack of blocks - scaled cubes stacked using a script.
They each have a rigid body applied and are on a passive plane. When I start/run the simulation, they all start to shake, wobble and eventually collapse. I tried changing the friction and margin, but I’m not seeing a way to keep them from falling until something hits the blocks. Any advice?
there are several “fixes” for this… one would be to increase the simulation accuracy via the “scene” tab of the properties window…
depending on the size of the block stack, you could try to increase the steps per second and solver iterations for the rigid body world… values I find myself using are:- 240 steps per second and 120 solver iterations… this may be excessive so you can find a balance between simulation speed and accuracy… the higher the values , the higher the accuracy , and the less “wobble” you will encounter.
another thing you may want to try in this tab is the “split impulse” option , depending on the nature of the “wobble” this can often help stabilize simulations… it can also often have the opposite effect, so try it, and see what happens.
As well as using this method you could make the rigid body objects “sleepable”, on the physics tab (properties window) of each rigid body object, at the bottom there are options for “enable deactivation” and “start deactivated” … there are also a few sliders to manage this property… ticking both of these options will make the rigid bodies “static” up until they are influenced by an outside force or collision.
A mixture of these methods would be best… try to find the balance between speed and accuracy.
one more point i would mention, is the “type” of rigid body can also have an effect… “box” type rigid body objects are a lot faster than convex hulls or triangle meshes, so using BOX collision methods can often be very useful to improve simulation accuracy…
Hope this helps 
In the physics panel at the very bottom (under Rigid Body Dynamics) is a switch for Deactivation. You’ll want to set your blocks to be deactivated at the start (Start Deactivated). This will keep them from moving until something interacts with them. Unless of course, you’re in the Game Engine, disregard since I have no idea.
Not using the game engine. I’m wondering if I need to follow actual design construction of I’m staking blocks 20 pieces tall. I tried the above suggestions, but still have the problem with the blocks falling over without anything hitting them. The settings did improve, but they still eventually fall over. Setting the blocks to deactivate prevented anything from interacting, but they still eventually fall.
edit: I forgot to set the “start deactivated” to true - works great!!! thanks much