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  • Hacking the 101Hero: Cooling Fan

    Posted on January 6th, 2017 admin 1 comment

    One weakness of the 101Hero 3d Printer is the lack of a cooling fan.   Most users have compensated for this with document.write(" Wiring, Cooling Fan" href="http://blog.graywriterrv.com/?p=1549">bed-mounted fans.    But wouldn't it be neat to add a cooling fan to the head, to direct cooling air right onto the recently-printed layer, just like on a more expensive printer?

    Where to Mount the Fan

    There are two likely places for such a fan:

    • In "front", under the filament access door.
    • At "back", under the hump of the stepper motor

    I thought the front location might interfere with access to changing filaments, and the shape of the duct would be difficult due to the need to fit in the yoke between the struts.   I also briefly considered mounting a fan on the top, beside the wiring and the filament tube, but thought that would be awkward.  Because of that I chose the "back" position.

    Choosing a Fan

    The 15 mm fan (for Raspberry Pi)

    The 15 mm fan (for Raspberry Pi)

    In either location, there isn't much room.   At the front, there might be space for a  20 mm fan, while at the back, the most likely size is 15 mm.  I got a tiny 15 mm fan on Ebay for $10 plus $7 shipping, and found a 20 mm fan at Aliexpress for $10 with shipping included.

    The little 5V fan came within two weeks from Las Vegas.  It pumps 12 litres/minute at 15.7kPa, a fraction of the amount from the 40 mm fan I have mounted on the print bed.  Still, directed through a duct, that small amount of air might be enough to cool the PLA.

    Besides,  this is just a fun project, intended to help me learn to use 123D Design and to do 3D printing.  It is not expected to produce any really practical result.

    Fan specs.  Sprechen sie Deutsch?

    Fan specs.  Sprechen sie Deutsch?

    Developing the Design

    I wanted something with minimal curves, with minimal interference with the airflow.  I dismounted the head, did some measurements, made some sketches.  The first prototype was made of stiff paper from a 2016 calendar, taped together.   The idea was that the fan, at the top, could blow down through a duct and the air be directed downwards beside the extruder.  I taped the fan into the top, hooked it to a battery, and decided that maybe....

    Crude paper prototype

    Crude paper prototype

    It fit well onto the print head, and it looked like the design might work.  Now all I had to do was turn that paper model and my concept into a 3D print using strange software such as TinkerCad and 123Design.

    Iteration After Iteration

    This part was enjoyable, if a bit tedious.  I would figure out make a design (which often involved a lot of Google work), then print it out.  Then I had to play with the print settings or the part orientation to get a decent print.  Then I'd try it, see what was wrong with it, which also often involved Internet research on "3D printing problems:.  Then repeat.  And repeat.  And repeat.

    A few of the many tries.  I went through five major designs with up to 12 iterations in each.

    A few of the many tries. I went through five designs with up to 12 iterations in each and used many meters of PLA

    One obstacle was that I couldn't really measure or fit with the head mounted in the printer.  With the head off to measure and fit, I couldn't print.  Once I put the head back, it often took hours (in one case a full day) to get it readjusted to print properly.

    fan-concept

    First two-part prototype, joined and sealed with green vinyl tape. Early versions included a screw mount for the fan but a press-in flange worked fine.

    Still, the early printed prototypes snapped securely onto the print head, and were encouraging.   Problems with printing led me to cut the part into two, a motor housing and a duct.

    Early prototype clinging to the print head

    Early prototype clinging to the print head

    v5-6-cooling-fan

    A mid-series Image from 123D. Motor housing at left bottom on plenum; duct at right.

    So, change this, extend that, find that this didn't print properly -- why not?--move this, try again.  I learned about support, orientation, bridging, wall thickness, stringing, retraction.  I switched from Cura 15.02 to 15.04 because the latter gave more accurate slicing (in between two Cura versions, I tested KISSlicer, Repetier Host, Craftware, and ICEsl) .  I changed setting after setting and kept track of all the changes in a spreadsheet, so that eventually I could identify what worked well and what didn't.   One thing that caused problems was support - Cura insists on putting support inside the duct, which was impossible to get out and which left the inside rough instead of smooth.  I wound up using Support "Touching build plate" as it worked the best. printing-v5-12

    The semi-final version was printed using the best quality I could achieve given my limited knowledge and skills.  There may be further modifications to indent the motor housing just under the motor, to allow space for the suspension struts during wide prints.

    Anyone interested in duplicating or better yet improving this project will find the files at the 101Hero forum (101user.com).

    Is it Safe?

    I'm printing in PLA and perhaps having the blower close to the extruder is not a good idea. I am considering sending the part out to be printed commercially, or waiting until I get my Trinus so the duct can be printed in ABS (the blower housing can be PLA).   Though, in point of fact, the thing hasn't melted yet.

    An early version, not quite straight and a bit close to the extruder nozzle

    An early version, not quite straight, not the best print, and a bit close to the extruder nozzle.

     

    In Conclusion

    In the end, I came up with a design that seems to work as well as it's going to work.  I'll print another Eiffel Tower to see the result.  Does it function and adequately cool the part as it's printing?  Probably not.  It seems that 12 L/m of air at 15.7 kPa is not really a lot of movement or pressure. I can feel air coming out the vent, and that's about as much as I can say for it.

    Still,  the project taught me a lot about using design software, principles of good design, and some basics of 3D printing.   Which was, after all,  the main goal.

    Further Reading

     

     

     

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