# BOSL2 alignment precision problem in OpenScad

Why my small cuboids are not perfectly aligned with the big one?

include <BOSL2/constants.scad>

diff("remove")
cuboid([1, 0.5, 0.2], anchor=BOTTOM){
attach(RIGHT) cuboid([0.2, 0.4, 0.1], anchor=TOP, $$tags="remove"); attach(LEFT) cuboid([0.2, 0.4, 0.1], anchor=TOP,$$tags="remove");
}


Attached objects will be overlapped into the parent object by a little bit, as specified by the default $overlap value (0.01 by default), or by the overriding overlap= argument. This is to prevent OpenSCAD from making non-manifold objects. You can also define $overlap= as an argument in a parent module to set the default for all attachments to it.