Designing a 3D printable D6MG plastic box enclosure for custom made circuit board
Summary
D6MG — Plastic enclosure on DIN-rail light gray color, production is made of heat-resistant high-impact ABS plastic. Overall dimensions are; length 106.25mm, width 90.2mm, height 57.5mm. [1]
In this prototype project, we aimed to enclose our custom electric circuit based on Arduino Uno. D6MG box was 3D designed according to its datasheet [2] along with four threaded screw housings severing as Uno adapter, mounted on the box base-part [3]. The prototype manufacturing will be done using a 3D printer. 3D Printing enables us to quickly and cost-effectively get our hands on the prototype and test the design before investing in any costly tooling. The later an issue occurs, the more costly it will be to fix it. 3D Printing Prototypes or rapid prototyping enables us to test the concept idea, check the functionality, and even include a sample part for potential inputs, all without cutting a single element.
Design considerations
The scale of the printed 3D model should be less than the printer building volume. In our case, since we are using Original Prusa i3 MK3S [4] This means the width, the length, and the height must be less than 250 mm, 210 mm, and 210 mm respectively which fits within it D6MG box.
The academic version of Solid Edge 2020 has been used in 3D modeling. Version 2020 has additional features. The key feature is a 3D Print toolbar, with clear wall-thickness and Overhang measurement tools. Wall-thickness, Overhangs, Height, etc. are important criteria for 3D printing as they are directly related to the Printer’s main properties such as nozzle diameter to decide whether the part is printable or not. Solid Edge also offers to export parts in several formats and extensions including “.STL”.
D6MG consist of 5 main parts, after part, is designed according to the datasheet, some optimization took place for the 3D Printing process.
D6MG cover optimization.
Part thickness before optimization
The part after optimization for 1.6mm minimum thickness. “with a 0.4 mm nozzle a minimum 0.8 mm wall can be printed. For the designed enclosure, a 1.6 mm wall thickness is recommended (must be a multiple of 0.4 mm).”
Cut-out at the bottom is removed to make it 3D printable.
Before optimization.
After optimization, Cut-out removed at the bottom
D6MG Guard optimization.
Part thickness before optimization.
Cut-out needs to be removed at the bottom to optimize it for 3D printing.
After optimization when cut-out removed.
Part thickness before optimization.
The thickness of the base is 0.7 mm, that is not possible to print with 0.4 mm nozzle diameter
After optimization for a minimum of 1.6 mm thickness.
D6MG Base.
This part is optimized for 3D printing with minimum wall thickness 1.6mm for 0.4mm nozzle diameter.
D6MG Body
This part is also optimized for 3D printing with minimum wall thickness 1.6mm for 0.4mm nozzle diameter
D6MG wall clip.
This part is very small, and it is not possible to give it a unified minimum of 1.6 mm, however, it is still printable using 0.4mm nozzle diameter as it has a minimum thickness of 0.8, and the details are good.
Exporting the Parts.
After parts are finalized, it is exported in STL format files to be later imported to the different soft
Preparing for printing
We used PrusaSlicer[4] and/or Meshmixer[5] for printing / generating the G-Code. We import all parts to Meshmixer in order to find the best possible orientation and to generate support material. Starting with setting up the printer parameter in Meshmixer;
While we follow a 45-degree rule that restricts, as far as possible, all overhangs of 45 degrees or more with respect to the Z-axis, D6MG box parts have sharp and simple geometry, so finding the best orientation is not a major challenge. This was the reason why we eliminated the base cut-outs of certain parts as we thought about the placement of the part. Since all of the box parts will fit inside the printer volume, adding all of them to print at once would save us time.
Before 3D printing, any part, the designer or engineer should be aware of the printing objective in order to be able to set specific criteria and utilize the resources. In our case, we need to have an industrial enclosure plastic box, so keeping its parameters unchangeable is critical for any mechanical system integration later if any. The box does not have ultra-fine details, so the quality design should be enough for this prototyping. We also have a spare day for printing because we are not limited by company deadlines. Accordance with the above objective, we can exchange time and support material with the D6MG industry-standard dimensions parameters and assembly possibilities.
Slicing trials of varying printing quality took place as shown in the tables below.
TABLE 1: Material usage and printing time using PrusaSlicer support material generation
TABLE 2: Material usage and printing time using Meshmixer support material generation
Conclusion
The tree-structure support provided by Meshmixer is slower to print but uses less filament and is easier to remove. The quality printing “0.20 mm” time between using PrusaSlicer support and support Meshmixer is around an extra 5 hours, although it seems a huge difference, we will go with it as it falls within our booked printing day.
References
- D6MG box: http://www.gainta.com/en/d6mg.html
- D6MG box datasheet: https://docs.google.com/gview?url=http://www.gainta.com/pdf/d6mg.pdf
- Arduino Uno RV3 Board design: https://cc/documents/ArduinoUno.dxf
- PrusaSlicer: https://www.prusa3d.com/drivers/
- Autodesk Meshmixer: http://www.meshmixer.com/
