Position (Height) of Hotend Fan Shroud

Discussion in 'Calibration, Help, and Troubleshooting' started by Old_Tafr, Jun 8, 2016.

  1. Old_Tafr

    Old_Tafr Well-Known Member

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    In the "Step by Step" assembly section of the build WiKi Section 20.3 "Installing the hotends" In the 11th, 12th and 13th picture it shows the blue shroud being fitted to the hotend fan, and then the whole assembly being fitted to the heatsink. This blue shroud is not symmetrical, it has a cutout on one side

    The cutout is shown at the bottom at the same level as the wires going into the fan body. With the cutout at the bottom (not easy to see in the picture) and with the shroud installed as low as possible on the heatsink, the shroud does not come into contact with the heater block, it in effect curves around it.

    Assuming this is correct, and there would seem to be no reason to have the cutout at the top or left or right, the shroud can be placed such that if placed as low as possible (by virtue of the cutout) there is a gap (seen if you fit the shroud as low as possible without the fan) allowing the fan to blow on the heatbreak and the top of the heater block.

    This can only be seen if you fit the shroud first before attaching the fan to the shroud. If you follow the instructions in section 20.3 you will not be able to see exactly where the shroud is fitted.

    The instructions at this stage (maybe later?) didn't mention the orientation of the shroud (cutout) or the height it should be fitted to the heatsink i.e. should the fan blow directly on the heatbreak and therefore on the top of the heater block OR just into the gap in the heatsink above the first (lowest) fin if you fit the shroud a few mm higher.

    Blowing on and therefore cooling (the top of) the heater block itself could mean it is cooled too much, leading to problems reaching or maintaining the correct temperature, it could be the reason why the temperature varies five or six degrees from the set temperature as seen in OctoPrint, (oscillating about the set temperature) with the heater constantly fighting to maintain the right level. There are likely to be other consequences, maybe the heater block never reaching the set temperature if this is particularly high.

    There could of course be no consequences at all? but it would still be worth knowing which is the better position to have the shroud in, both if the cutout should be at the bottom and in what position the shroud should be on the heatsink.
     
    #1 Old_Tafr, Jun 8, 2016
    Last edited: Jun 9, 2016

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