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  • Hacking the 101Hero 3D Printer: Control Box, Wiring, Cooling Fan

    Posted on December 18th, 2016 admin 1 comment

    Here  is the second installment of hacks for the 101Hero 3D printer.

    Desired Changes to the 101Hero 3D Printer

    There are a few issues that have come up repeatedly in 101Hero user groups, as people get to know their 3D printers better.

    • Find some way to better locate the control box
    • Cover the exposed contacts on the SD card holder
    • Get rid of the tangle of wires
    • Arrange some kind of filament holder
    • Add a fan for cooling

    The final two are my own suggestions.

    • Illuminate the bed
    • Replace the stationery binder clips that hold down the build platform

    Some of these were discussed previously.

    Locating the Control Box/Tidying the Wires

    Control box mounted on a pylon

    Control box mounted on a pylon.  See how neat the wiring is?

    The control box is evidently designed to sit on the work surface beside the pylons.  But two of the wires from the limit switches are really short and one is twice as long; probably the long one is supposed to wrap underneath with the short ones and the control panel goes on that side.  But once I noticed that, I wasn't interested in disassembling the printer, and neither side seemed particularly good.  (It only occurred to me after I did all this work that I could have put the control box where it was "supposed" to go and simply re-oriented the print head!)  The wires from the limit switches and stepper motors sort of sprawled alongside.  It was functional but unsightly and the wires kept snagging on my tools.

    Control box from the "front" of the printer

    Control box from the "front" of the printer.  Note the LED on the "wrong" side

    My solution was to mount the control box, switch end up, to one pylon with Velcro tape.   I chose the opening that accesses the filament change gate as "front" and put the box on the pylon to the right.  Why the right?  Because it was closest to the wall receptacle; had I put it on the left, the power cord wouldn't have reached!  I opened the control box and re-routed the power LED to the opposite side just above the USB port, so it would be visible.    This required me to extend the two short limit-switch wires so they would reach.

    Pylon-mounted control box from the "back" side.  SD card is still accessible.

    Pylon-mounted control box from the "back" side. SD card is still accessible.  Note the cable ties and blue binder clip securing the wires to the pylon.  Real high-tech.

    The wires from the print head are very long and at first draped all over the place, so one of the first thing I did was to bind them using some gold plastic tape I had on hand from building RC planes.  Others have used spiral wrap;  automotive harness tape is another possibility; both are heavier than the model tape.  Once the control box was mounted vertically, I had even more surplus, and used a zip tie to bundle the excess. For now, a couple of binder clips secure these wires to the pylon.

    The wires are zip-tied together, keeping everything more-or-less out of sight.

    The wires are zip-tied together, keeping everything more-or-less out of sight.

    This keeps the printer footprint small, allows me to easily move the printer, and still allows access to all controls and inputs including the SD card.

    Cooling Fan

    Various 3d printing instructional sites have stressed the value of cooling the layers as filament is laid down.  One usual solution is to mount another cooling fan to the head, with ducting to direct the air at the work.   For the 101Hero, adding mass to the head might increase overshoot and further reduce the print speed of an already slow printer.  As with the LED lighting, this means perimeter cooling.

    LEDs with fan at back

    LEDs with fan at back

    I designed and printed a bracket to hold a 40 mm CPU fan that was sitting in my junk drawers.  The bracket attaches to two of the screws holding down the bottom plate directly in front of the "back" pylon.  This was a quick and easy solution, but as with the LEDs I will have to redo it to move it further back from the print bed.  Having the head whack the fan would probably do neither any good.

    A closer look at the fan bracket mounted

    A closer look at the fan bracket mounted

    Controlling the Lights and Fan

    Although the LEDs and fan draw only 90 mA between them, I didn't want to draw this power from the control board and risk underpowering the hot end or resetting the microprocessor.  If I do use the control box, I'll add a 5V power supply coming off the wall wart, which is 12V @ 3A and probably has a little extra.  Got to grab the ammeter and check.

    Incredibly ugly switch for controlling LEDs and fan.  I'll find a nicer switch but for now it works.

    Incredibly ugly switch for controlling LEDs and fan. I'll find a nicer switch but for now it works.

    The LEDs and fan are powered by a 6V battery pack tucked under the printer base, controlled by an ugly old 2P3T switch that was on hand. It's zip-tied to one pylon to keep it in place.   It gives me three settings - OFF, Lights ON, Lights and Fan ON. Manual control of the fan is clunky but fan control doesn't seem to be part of the 101Hero firmware.  At any rate, I can illuminate the work, then after the first few layers are adhered to the print bed, I can turn the fan on for the rest of the print.  If I feel ambitious, I might build in pulse width modulation for speed control and incorporate the light/fan/speed into the control box.

    Further Reading

     

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