Hot end assembly
The airflow system
The stacking height of the fan, heatsink duct, fan duct and the heatsink adds to 40mm, which leaves the 40mm screws too short to connect these parts.
A workaround that was employed was to file away part of the fan body such that a few extra thread turns were exposed to the aluminium cooling block
File:Http://mediagoblin.tami.org.il/mgoblin media/media entries/575/IMG 20131220 102740.jpg