POCKET DRAWBOT: First approach


Piccolo

After discussing the implications of formal and haptic design in the manufacture of machines and robots together, we agreed on the idea that we could create a small machine - even portable - and that its main function could be to write notes or draw sketches.
We decided to start by fabricating an existing beatiful open source machine called Piccolo: the tiny CNC-bot and thus verify if we could adapt and improve the mechanism of movement in 3 axes.

Here are the ingredients:

  • Laser-cut Parts in 3mm MDF, 2.7mm acrilyc and stockboard
  • 3x Micro Digital Servos
  • M3 Cap Screws and nuts
  • Piccolo PCB with Pro Micro or another Arduino Compatible board


  • And here are the assembly instructions

    After some local adjustment of some parts and joints (we did not get the M3 Cap Screws and nuts in time) we were able to assemble our little drawing bot. The result is good and beautiful but the movement is still not fully fluid on the x and y axes.

    Laser cutting parts

    The laser cutting file was available online so we only had to download it and make sure to have all the materials available in our fablab -which we did-


    First 3mm mdf:


    Then 2.7mm acrilyc:


    Then stockboard:


    This thin layers were supposed to be

    For more info on later cutting you can visit my third weekassignment

    Then the model wasn't parametric, we just found a stl file and a vectorial file meaning adjusting the lasser cuting file can be a lil bit tedious.

    I wonder if there's a way to parametrize slots and joints with a linear ecuation. This means to set the with of the slot for example to 1ex1.005 (being e the with of the material). This means that if were able to know what percentage of the with the machine burns we don't have to fix a value. Or does de machine burns a constant value that's independent of the material width?


    Assembly

    We followed thistutorial which was pretty self-explenatory.

    At first glance, what could be improved here is the assembly between parts. We did not find M3 screws and nuts and the more similar ones were still not the best choice. Also, he pen holder isn't as firm as is should be.

    mdf is cheap and nice but is kind of rigid for manipulation an once cracked or bended there's not really a way back. I rather using cardboard.


    What was carefully designed here was the cable slots. See how pretty?


    Below two servos (x-y) boxed into the mdf parts.

    Also, you are expected to need paper staces made of stock board. This can be thoughtfull but not really precise..I want to rethin this in terms of joints:


    Mechanical manipulation

    There's still some adjustments to be done here. Joints are not as precise for the size, therefore the movement in y is not as fluent as it should be.

    The movement in Z is the only one -almost- fluent.

    NExt week we will def tackle mechanisms: smoother movements and a more stable and if possible more precise joints.


    Here's Santi and my hand doing magic...not really we needed a smaller nut and were trying to fit it (more mentally that pisically) somewhere.


    Board and Programming

    This tutorial was a life saver.As you may see Processingneeds to be downloaded (Arduino too of course) and some Processing libraries (for both programs)


    Quick tips for adding libraries: you need to add the whole zip file here:


    You would then be able to install the library here as I did with attiny in my fourthweek.


    The piccolo design had its own board but could also be both, programmed and used with arduino UNO and basic breadboards connections. Here the breadboard connections


    Each servo is connected to the arduino UNO as it follows:



    POCKET DRAWBOT: Second approach


    We could not make the Piccolo machine work well, the movement on the z axis was the only one we could control with some difficulty. In this second opportunity we decided to go for our pocket drawing machine made with printed 3D parts.

    We did not start from scratch, we took as a base the Mini 3-Axis CNC machine, a collective project in Thingiverse site.

    As we are two people studying at FabAcademy we decided to work simultaneously. So at the time Mercedes was making tests with the servo motors using an Arduino IDE with a UNO board, i was adapting the models that they could receive better the small gears of the servo motors. After some tests These are final Cura settings for the 3d printed parts. After having the pieces printed i performed the assembly (following this tutorial). I had to make some extra manual adjustments by adding a separator to the gears parts to work fluidly, for the realization of second prototype this could be improved with 3d design. We followed the instructions of this site to program our small pocket robot using an existing Arduino Code (You can download it below). Arduino succeeds compiling and uploading the sketch to the board. but the servo motors keep spinning to the same direction all the time ... We have not yet been able to make drawings yet ... We will continue to work on programming to achieve that goal!

    Here are files of our tiny project.

    See our pages for more information:

  • Santiago Vera
  • Mercedes Carriquiry

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