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  • 101Hero Cooling Fan: Proof of Concept

    Posted on January 18th, 2017 admin No comments

    The last test has been completed, and I'd say the cooling fan hack is a success!

    Climbing the Eiffel Tower

    One of the earlier prints I did with the 101Hero was a series of Eiffel Tower models, from Thingiverse.   There were tower models I liked better, but this one seemed simple and within the ability of the 101Hero 3D printer.

    The Eiffel Tower model

    The Eiffel Tower model

    They were generally good for the first  30 mm, but after that degenerated into a twisted, molten mess.  The diagnosis was excessive heat.

    101Hero Red PLA; two in Silver RepRap PLA

    101Hero Red PLA; two in Silver RepRap PLA

    • The first treatment, reduced print temperature, was not much better.
    • The second treatment a 2" (40 cm) fan beside the print bed to provide cooling, was more successful.  The print was reasonably good to 50 mm, with less twisting and globbing in the upper tower.
    • The third treatment, using a "cooling tower" to print beside the model, was less successful.  Excessive stringing made one corner of the Eiffel tower a mess, and in all was not as good as the previous print.

      Printed with cooling tower

      Printed with cooling tower.  Best side shown at right.

    Adding the Head-Mounted Cooling Fan

    The final test of this  project was to print an identical tower using only the head-mounted fan for cooling.  I scaled the height of the model to 75 mm, which was the measured height of the earlier series.  However, I did not duplicate the settings of those earlier models (I have learned a few things since then).  Being a bit impatient, I set layer height to 0.2 mm to reduce print time (this also seems to have resulted in the model being 80 mm tall).  I used support touching the buildplate, and a raft, because some of those earlier towers had lost a leg and suffered other detachment errors.

    The print went almost perfectly to about 65 mm.  At that point, the behaviour of the head changed, and instead of printing a bit and waiting, it began running continuously.  I could actually see the head dragging the molten plastic in a small circle.  Five millimeters later, the head went back to printing a side, waiting, printing a side, waiting....   This seems almost to be a setting error, one I might be able to track down in the gCode.

    Test Results:  Left, head-mount fan; center, bed-mount fan; right, cooling tower

     

    Test Results shown above: Left, head-mount fan; center, bed-mount fan (red feet tell you it was done right after the set done in red 101PLA); right, cooling tower.  Dang, it's in sharp focus on my computer, even zoomed in.  Why is it soft-focus here?

    The final proof - identical settings, on left with fan, on right with no fan.

    The final proof - identical settings, on left with fan, on right with no fan.

    Conclusion

    Woohoo!  The head-mounted fan created the best-looking print.  We'll call this a success!

    But this isn't the end.   Ideas for the future:

    1.   I might want to extend the duct to move the vent about 1 mm closer to the extruder nozzle.
    2.  Another possibility is to add a ring-shaped vent to surround the nozzle.  However, my first attempts at this failed, since this project was done at about the limits of accuracy for the 101 Hero.  Doesn't mean it can't be done.  Just means I couldn't do it a few weeks ago.
    3. I might wait until my next printer comes, and print another fan system in ABS
    4. The little rotary fan really doesn't move much air (1.2 litres per minute).   If I can find a small centrifugal "squirrel cage" fan it might improve the cooling.
    5. I'd like to experiment with an aquarium blower, which pipes air through a tube.  I'm thinking a 1/8" metal ring around the nozzle, with holes drilled for the vents.

    Lots of fun still to come.

    Further Reading

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