Tree-like (spot) model support in 3D printing

    The article describes the personal experience of creating and applying tree-like supports when printing complex objects on a 3D printer.



    Usually, support is created when 3D printing is done in gcode generation software, for example in Cura, right before gcode generation. The easiest way to print objects in the form of a pyramid is on a 3D printer. Then each next layer lays on the previous one and does not hang over empty space. Supports allow you to print overhanging parts of objects, but standard supports are not always optimal in terms of plastic consumption and the simplicity of their subsequent separation from the object itself, so in this article I will describe my personal experience in creating and using tree-like supports.

    Creating Tree Support

    Supports are created by the graphics program, in the case of MeshMixer in automatic mode.
    For a program for generating code for a 3D printer, the result of MeshMixer will be a continuation of the model itself.
    You can create manually or edit already generated (just).



    Benefits of Tree Support

    1. Full control over the process of creating supports.
    2. Easy to clean model.
    3. Slight traces. With a successful setting, they are completely absent.
    4. Saving plastic in certain cases.
    5. Does not need a “Raft” substrate

    Disadvantages of Tree Support

    1. The probability of failure of the support is relatively high.
    2. Skills are needed to create supports (tasks printed for the first time should not be left unattended. This way you can save plastic on unsuccessful results).
    3. Support for horizontal planes requires a large number of support points, which can negate the savings on plastic.



    Tree Support Perspectives

    1. There is a new feature in printers that allows you to jump over supports without breaking them.
    2. The Slic3r code generator does the same, due to the order in which the extruder moves, bypassing the one already printed in the print plane, without resorting to height movement.

    Areas of use

    The question is not unambiguous, and depends on both the model and the material.
    The main trends that have so far been identified:

    1. Material : PLA support, in the aggregate of all other factors, will show a better result than in the case of ABS. Due to the properties of this plastic, the drop in “strength” of the material between the layers is compensated by flexibility. But if you make the supports too thick, they will break guaranteed. PLA is also characterized by ductility, due to which the part is wrapped in a thin web of such threads, and previously lost support can grow further from the moment of breaking, relying on these fibers from neighboring supports.



    2. By the heights of supports: The greater the height, the greater the effect of tree support can be obtained. From 6 mm the effect grows from “nothing” in increasing dependence to “very much”.
    After a height of 35 mm, the generated supports are better reinforced independently in the program itself with additional trunks.



    3. On the vertical slope : The smaller the angle (ie, the less the overhang), the greater the effect. And in the case of horizontal (for example, ceilings) tree-shaped point supports are inferior to “linearly supporting” (standard supports), since the printer prefers to build “bridges” between two lines rather than a group of support points.



    4. By surface detailing : Spot, it is tree-like support is preferable for a large number of parts (fingers, frames, grids).

    5. In proportion: The ratio of height to width and base plane. Point tree support is preferable in cases of predominance of height.
    Although most of the remarks are speculative, they should be sorted out in the mind, constantly gaining experience in printing, and analyze the degree of their influence on the result, having clearly laid out the directions of dependencies and trends.

    Creating Tree Support

    Tree support is easy to create in any graphics program on its own and without generating the program. But programmatically, this is implemented in Meshmixer. www.meshmixer.com/index.html

    This function in the program itself is implemented in two different modes: with or without the [2] Convert to Solid key.
    Using the Overhands function, you can immediately set up a “tree” by analyzing the model for all compatibility parameters with 3D printing.



    And you can go to "Mode model location in the workspace of the printer" and create support there.
    In both cases, regulatory authorities are more than enough. The influence of some of them on the result has not yet been identified empirically explicitly and conclusively.
    But some regulators can greatly accelerate the processes of generating supports and preparing for printing.
    The first thing to reduce is the number of sides to a minimum = 3, then the supports will become triangular and the experiments will go faster.
    This is done in the “Advanced Support” expanding menu. “Post side” value.

    Creation - support generation occurs only after pressing the button [1]. And new parameters will be applied only after deleting old ones and generating new ones.

    Multiple experiments can give a fairly clear idea of ​​a change in the proposed parameters.

    Such experiments only lose sight of what the printer itself is physically unable to print: these are the sharp ends of the supports. The model will just hang, and the tips of the supports will not reach the target surface.
    In great detail, it makes sense to raise the entire model above the table with supports, this will make it possible to compensate for temperature shrinkage due to the flexibility of the supports. The part, cooling down, will be compressed and will not come off the table during printing.




    This effect is pronounced, mainly in hollow and frame (wireframe) models.

    Conclusion

    This method is a simple but flexible tool in settings, expanding printing capabilities, saving plastic and time for cleaning parts. With the prospect of development. Provides the ability to combine.

    PS Predicting the question of the model in the photo. This is part of plastic plaster for one of the internal projects of the Campus Navigator .

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