Fan duct for RepRapPro Ormerod using dual fans. One cools the hotend heatsink, the other cools the print. The advantage is you can completely disable the "print cooling" for example when printing ABS, and have software-controlled fan speed while still maintaining hotend cooling. As the hotend can be kept cool with quite low airflow, that fan can be slow and silent. This design uses a 5010 50mm 12V radial blower, that can just be glued to the fan duct (I used plain CA glue). The original hotend fan is probably a bit too thick, I replaced it with a thinner, slower one. With these two fans (the "print cooling" fan at 50% which is sufficient for normal use) the printer is much quieter than the stock fan, and with the radial blower at 100% there is a lot more air over the print. The fan duct is based on dc42's fan duct and works together with his sensor board. That is in turn based on iamburnys design. While this was designed for the Ormerod, it might fit other RepRapPro printers that have the same hotend cooling block.The hotend cooling fan (the 40mm axial fan) connects the "normal" way, either wired permanently to 12V, or temperature-controlled via the sensor board. The print cooling fan (the radial blower) connects to the Duet. I'm using a plain 3-wire fan, and control the speed via the FAN0 output header. This requires more cables through the cable loom. Simplest is probably two cables straight to the FAN0 header, but it is sufficient with one for the "-" side (black cable), as the "+" side (red) can be connected to any other 12V source such as the existing fan or the hotend heater.