Qidi Plus 4 Hotend air duct

• 20-5-'26 Update
  
  If you have a Pheatus Conch hot end, there is a new model upload for it of this duct. This will fit without having to force the Conch hot end behind the original duct in this upload. You can find the new Conch version here

• 3-11-'25 Update
  
  I have made a revised version “V5”. This model has a slightly larger recessed area, allowing for a bolt head with 3mm height and 6mm diameter.
  
   

After experiencing another clogged nozzle caused by heatcreep with my new Qidi Plus 4, while printing PETG, I decided to investigate and see if I could find a solution. 

The standard hotend has the fan directing airflow towards the heatsink from a distance, with no airflow being directed specificly at the hotend heatsink. The gap between the fan and the heatsink is enough for hot air, from around the heating cartridge, to be sucked into the flow directed at the heatsink and this is suboptimal for the cooling of the heatsink which helps prevent heatcreep. 

Printing with my ventilated and closeable riser unit open or the lid taken off and the door open made no difference. I had several clogged nozzles with the same PETG printed part. 

I designed this small duct to close the gap between fan and heatsink. Air flows directly from the fan onto/into the heatsink, causing much better cooling. The printer just finished a 22 hour PETG print with this duct attached, printing the same part that had heatcreep clogs earlier, and it finished without any issues or clogs. 

For this duct you will need to remove the 2 bolts holding the fan bracket to the hotend carriage. After you have unscrewed the fan from the backplate, be careful not to damage the wires from the fan. You can use the original screws to secure the fan shroud and fan back on the bracket. I instead of the original self tapping screws, used 2x m3 - 16mm ball head Allen bolts to secure the duct and the fan to the bracket. No need to drill or tap the holes, I was able to simply screw the bolts into the existing holes. 

Re-attach the fan + bracket back onto the carriage and replace the front cover. 

I printed the part in PETG-cf for better heat resistance. While this will hold up well when printing PETG, PLA and most likely ASA and ABS, this is not nearly enough for printing with materials like PPS-cf or PEEK.

Ideally you want this printed in filament with a very high glass transition temperature, since this printer has a hotend that can reach temperatures reaching up to 370C.  

PPS-cf comes to mind as the ideal material for this. 

• First layer 0.2, following layers at 0.12

• nozzle size 0.4 with 0.4 wall thickness 

• 3 walls 

• 5 top and bottom layers

Optional Hardware needed:

• 2x  m3  16mm  ball head Allen bolts

If you want to support my work, feel free to buy me a coffee :)

https://buymeacoffee.com/3dmadmesh