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Large cartesian 3D printer with fixed bed

Discussion in '3D printers' started by Robert E. Nee, Apr 1, 2017.

  1. Robert E. Nee

    Robert E. Nee Well-Known
    Builder

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    Robert E. Nee published a new build:

    Read more about this build...
     
    MaryD likes this.
  2. luis felipe barbosa

    Builder

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    Dear Mr. Nee,

    this is a very nice project that you're developing. Currently, the mechanical students from the technical school where I am teaching (Colégio Técnico Industrial de Guaratinguetá from São Paulo State University) are also designing 3d printers, and one of our 3d printers is very similar to yours. Our main doubts is, however, related to the stepper motor selection. Most of 3d printers are built without any estimation of required torque.

    Surely your project stands out in this point, because you carefully selected the stepper motors for each axis. I've just downloaded your documents about the stepper selection, and I'll for sure use them in our projects. In additional, there are some interesting materials about motor selection, and I would like to share them with you. In [1], there is available an online tool to determine the required torque for several cases. In [2], Jonathan W. Valvano from the University of Texas at Austin provided a technical report regarding stepper motor selection. This report seems to be very interesting.

    Good luck with your project!
    Best regards,
    Luís Felipe

    [1] Motor Sizing Tools

    [2] http://users.ece.utexas.edu/~valvano/Datasheets/StepperSelection.pdf
     
    #2 luis felipe barbosa, Nov 9, 2018
    Last edited: Nov 10, 2018
  3. Robert E. Nee

    Robert E. Nee Well-Known
    Builder

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    Thank you for your kind words, however, I wanted to be more scientific in the motor selection than I actually achieved. For instance, I could not obtain the strepper spec sheets for pull-out torque versus stepping rate for either my nema-17 or nema-23 motors. I defaulted to using nema-23 motors. Also, my efforts at heat plate simulation were disappointing as Matlab provided several different methods and their results did not agree. I had a preconceived view of what the results should look like when radiation is enabled and it turns out aluminum emisstivity has two values depending on whether the aluminum is anodized or not. My aluminum plate is non-anodized with emiss = 0.08 versus emiss = 0.85 for anodized aluminum. With such a low value of emmisity, radiation is effectively disabled whether the simulation switch is on or off. I ran simulations later with emiss = 0.85 and as expected the plate temperature plateaued much quicker. Your referenced links are helpful. I rushed into my build and ended up reworking much. My gantry design suffers from the fact that everything must be moved to move the printhead. I did not want to raise and lower or move the heat plate. I would have more confidence for a much smaller effort but I already have 2 3d printers of "normal" size.
    Good luck with your builds,
    Robert E. Nee
     

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