[ODE] Joint instability with small bodys

[Patrick McColgan]

Hello, I'm having difficulties with using the standard ODE joints with 
'small' objects.

Whilst bodies with dimensions around and below 0.2 are fine colliding as 
rigid bodies, creating constraints between them produces constant 
instability.  My basic test has been to have a static body floating in 
midair (using a fixed joint) and then attach another body to it using a 
ball or hinge, the joined bodies do not collide with each other and are 
not close enough to collide with anything else.

Has this come up before?  I searched the archives but found nothing I 
felt was relevant, I know it has been said here before that measures 
should be kept around 1.0, certainly constraints prove to be fine with 
higher values but has anyone come across this before and maybe found 
ways to deal with it?

I'mn using double precision but is this likely to be a numerical 
inaccuracy problem?