What is the purpose of the recess in the latest Extruder Cover STL ?  

RE: What is the purpose of the recess in the latest Extruder Cover STL ?

It doesn't appear to have any purpose that I can see, other than to reduce material use.

RE: What is the purpose of the recess in the latest Extruder Cover STL ?

Perhaps it's to aid better airflow to the cooling fins by creating a low pressure spot, therefore aiding the Venturi Effect?

RE: What is the purpose of the recess in the latest Extruder Cover STL ?

It is used to improve cooling by using  the effect of venturi effect.
The air moved by fan inside the shroud goes through smaller diameter opening then fan itself. This increases the air speed and lowers the pressure, thus sucking more air via this side hole.

This is how Dyson "bladeless" fan works. (It has blades but hidden in the base). You can watch a YouTube video explaining how it works to learn something new.

RE: What is the purpose of the recess in the latest Extruder Cover STL ?

So its the fact there is a bump on the inside that is required not particularly that recess I ringed. I guess it could have been flat on the outside and still the lump on the inside of the fan duct.
Okay thanks for the replies that explains my curiosity 🙂 

Steve