I was getting errors when printing with Polycarbonate on a fully enclosed UM3 and determined it was a heat issue with the print head circuit board. This part replaces the back cable clamp on the print head on an Ultimaker 3. It attaches with the original screws. A side part cooling blower is used to force air over the circuit board maintaining the temperature about the board on a fully enclosed UM3 near what it is on a fully open UM3. This prevents communication errors from the print head to the main controller. These errors usually look like "print core #2 (or 1) is taking to long to heat up". The errors also prevent the print from restarting after the print has been paused. Some Data: This program prints 4 identical parts. 2 in ABS, 2 in Polycarbonate. Printer open (no cover no door) T=0 32C T=7:00 (minutes) 51C (end ABS) T=11:00 57.6C (end Poly C) T=14:00 59.5C (end ABS) T=16:00 61.1C (end Poly C) T=32:00 65.8C (end ABS) T=49:00 64.8C (end Poly C) Printer fully enclosed (starting about 3 minutes from previous ... printer fully warmed up) T=0 53.7C T=12 76.6C (end Poly C) T=40 86.0C (end Poly C) T=42:30 84.9C (end ABS) T=46:30 85.8C (end Poly C) T=50:00 85.3C (end Poly C) Printer fully enclosed using fan setting on printer (had to reset fan speed every 30s or so) T=10:00 71C fan on 50% T=11:00 65.2C fan off (the fan kept going back to zero) T=21:00 fan on 75% T=23:00 73.0C (end Poly C) T=25:00 74.9C (end Poly C) fan on 100% T=31:00 71.4C Printer fully enclosed, Circuit Board cooling fan on 75% in program from start T=15:00 64.6C T=45:00 66.0C