Cylinder d1 d2 vs r1 r2 are inverted.

[se5a]

this creates one cone pointing up and one cone down:

cyl1 = new Cylinder( { d1: 10 d2: 20 h: 30 center:[10, true, false] })

cyl2 = new Cylinder( { r1: 5 r2: 10 h: 30 center:[-10, true, false] })

assembly.add(cyl1) assembly.add(cyl2)