For those who got similar configurations like me (half circular fan duct - updated carriage)
I wanted to get rid of the IR Mount on the fan for the hotend (e3d V6) because i had problems with instable results.
The second problem was my half-circular fan duct.
So I designed one for this combination.
It should be printable without support an able to fit in the place for the right endstop.
The offsets suiting for my carriage (see photo) are
The probe should send signal at 0.5mm
Code for DuetWifi as an example
G31 P500 X38 Y-9 Z0.5