PCB Cube - desk calendar or completely unviable idea

    Not so long ago on Geektimes there was an article by Sergey Gryshchenko about the line of amateur radio and crowdfunding on Vkontakte . His experience encouraged me to implement the idea of ​​a desktop calendar in the form of a textolite die. First of all for myself, and trying to smash crowdfunding was the tenth case.

    I'll go ahead and say that the crowdfunding did not work out in principle and the article is not even about that. It turns out too expensive for a trinket serving as a podium for a rubber duck. The article turned out about some aspects of turning ideas into life that may be useful to a random habrauser. Who cares, I ask under the cat.

    The idea
    Honestly, even the idea itself does not belong to me. I saw a similar cube on one of the stands of ExpoElectronic 2016 in March. I don’t even remember from which company this stand was, perhaps little-known Chinese manufacturers of printed circuit boards, the cube was in English.
    I liked the idea. The cube has 6 faces, in a year of 12 months, I love textolite. It all fits. You can put on a work computer under the yellow duckling and twist in your hands, dreaming about vacation.

    Elaboration of the idea
    First of all I began to think about the construction of the cube itself. There were three options.
    Let's call them "children", "on the screws" and "hedgehog."

    The variant of the children's cube seemed unreliable due to the fact that the thickness of the PCB is several times smaller and it is not so plastic. A small error in the production and the cube will fall apart.
    I still like the idea of ​​the variant on the screws, but the problem was to find the inner corner inserts to which these same screws can be screwed.
    The option of a hedgehog I saw at that very exhibition, I stopped at it. Began to work out all sorts of options. I got three different faces, the contours of which look like this:

    Hidden text
    I am ashamed to admit, but I modeled the design in a furniture editor ... What ?! Very easy and looks visually.

    Preparation for production.
    So, in order to assemble a cube, it is necessary to order faces of various types. I got three such faces. We draw them bilateral (January-July), (February-August) and (March-September). See photo above.
    The size of the cube is selected 5x5x5cm due to the fact that it is the cheapest option for the Chinese. Resonit was not considered due to the cost of preparation for production, it is not profitable on a mock-up sample.
    Wiring done in Eagle Cad. The first thing that I encountered was the absence of the vector font of the Russian language, and sending the Russian Proportional font to the Chinese themselves can understand a bad job. The output was:

    Ie, we write the Proportional text of the desired size, and then simply draw it around with the Wire tool on the layer we need (in this case, it is a screen-printing layer). You can also create a library of elements, where a separate element will denote its letter, and then simply collect text from them. Crutches, and what to do? Who knows the solution better, I will be very happy to hear it. The change of CAD is not considered.
    The second point that I noticed is the mounting holes. The fact is that if you leave the holes and the outline of the board with right angles, then you will hardly be able to assemble the cube:

    And this is why. By production the mill which has a certain diameter is used. Moreover, in different places mills of various diameters are used. From here we get that we will never succeed in a right angle, and in life we ​​will get something like this:

    To prevent this from happening, in the corners we add the drilling of holes, and the diameter of the drill will be different, depending on the size of the cutter. I communicated with the support and found out the diameters of the cutters with which they will make my order. It is logical that the main circuit of the board is made a big cutter, and the holes in the board are already smaller. On itead, the minimum cutter diameter is 0.8mm.

    For three different orders of 10 boards 5x5cm, along with the delivery, I got about $ 40. Thus, in order to collect 10 dice, you have to lay out $ 80. It turns out a little more than 500 rubles apiece. The verdict is expensive. We look in the direction of Rezonita:

    At least some substantial gain in price can be obtained when ordering from 40pcs.
    And still it is necessary to take into account the cost of sending a small package by Russian Post, you can’t put six boards just like that into a mail envelope, as you could do with a PCB ruler.

    Results I

    am pleased with the result; it is pleasant to hold the cube in my hand. He has no practical value other than a desk calendar and a duckling stand.

    First reviews For the
    first time I decided to show the cube to people in the already familiar community Goods from China to the Radio Amateur , thanks to which the PCB Ruler line came out. The admin easily made contact, immediately got an idea and agreed to help.

    Created a discussion and post on the wall. Sergei, the author of the PCB Ruler line, was the very first to fit in, but it was not possible to collect the critical mass for the first order. The main argument is that it is expensive for such trinkets, it is cheaper to make plywood, etc.
    Yes, I understood it before.

    Why all this?!
    Sergey in the epilogue of his history expressed the hope that the article will inspire someone to create their projects. Inspired! Let not quite successful project, but for myself.
    Thank you for reading to the end.

    When writing an article, not a single rubber duck suffered.

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