Improved MK4 Fan Duct

This fan duct improves the air flow so the overhangs are better (up to 70º with very good quality, 3rd picture)

I recommend to use Prusament PC Blend-Carbon Fiber or PA11-CF, because they are heat resistant and to reduce weight mainly, but other filaments may work just as well.

I also recommend to use my improved fan door (to center better the fan duct): https://www.printables.com/model/621424-improved-mk4-fan-door.

Caution: from version 7.0 sometimes it is necessary to reduce the fan speed a little! A reduction of 5-10% from your previous profile is usually sufficient.

Warning 1: If the fan test fails, please remove this fan duct and pass the test; then reinstall the fan duct. The original fan duct does not need to be installed to pass the test, it is simply left free.

Warning 2: it is recommended to be used together this model (or similar): https://www.printables.com/model/566871-mk4-hotend-fan-shield-eliminates-turbulence-drafts. It prevents air turbulences from extruder fan.

Note: This fan duct can not be used with MK4S because its different fan duct new design.

Printing Parameters:

• 5% infill
• 0.1 layer height 
• 3 or more perimeters

Changelog

V3 (2023/10/21)

• Initial release (removed)

V5 (2023/11/12)

• Better flow air.
• Divider to balance the flow air from left and right.
• Custom supports (can be removed, use split parts on PrusaSlicer).
• Optional: to be used with my improved fan door (https://www.printables.com/model/621424-improved-mk4-fan-door).
• Optional: .3mf file with multicolor version.

V5 (2023/11/13)

• Solved small bug on the fan opening, please reprint again!!
• Removed

V6 (2023/11/14)

• Same fan duct with 5% less weight
• 9.40g printed with PC Blend Carbon Fiber

V6.1 (2023/11/18)

• Fan duct lowered 1.5mm to better reach nozzle tip (less air in nozzle block)

V6.2 (2023/11/28)

• More separation from heatbed (0,5mm)
• Around another 5% less weight

V6.3 (2023/11/30)

• Around another 3% less weight
• Slightly improved air flow
• Pass fan test!

V6.3 Inserts (2023/12/01)

• Variant to use M3 thread inserts (M3x4.6x5.7mm)

V6.4 (2023/12/26)

• I think now air flow is perfectly centered (please, see videos) 
• https://www.facebook.com/groups/1910026672591728/?multi_permalinks=3492081117719601¬if_id=1703616893038356¬if_t=feedback_reaction_generic&ref=notif
• Can be used with thread inserts or without
• Pass the fan test

V6.4 (2024/01/30)

• Removed all the previous versions

V6.4 Wider (2024/03/18)

• I have added a wider (1mm) version, in some cases seems it is not well centered (due to the fan door, mine reduces this)

V6.5 (2024/05/12)

• Increased air flow pressure
• Improved custom supports, easier to print

V7.0 (2024/05/16)

• Even easier to print, it doesn't need supports
• Better air flow distribution
• Slightly increased air pressure
• As v6.5 can be used with or without threaded inserts
• Removed 6.4 versions

V7.1 (2024/06/26)

• Added a small flange ("triangle") to prevent fan angling upwards, all merit to: jaxman smitty by this suggestion