19hertz

ramblings of an electronic engineer.

SatNOGS Build: 3D Printing

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So for the SatNOGS build there are around 21 parts (unless I counted in my head wrong) that are required to be 3d printed for making a ground station with a total print time of somewhere between 45-60 hours depending on which settings you use (guess how I know!). For my build I was fortunate to have access to my work’s Ultimaker 2 3d printer with which I was able to knock over all the parts over in around 2 weeks. IMG_3513 For the majority of the parts I printed them with a layer height of 0.2mm, 30% infill, 0.6mm top/bottom, 0.8 shell thickness and for the majority of the parts there were no problems, except for this part: IMG_3521 This is the worm gear of that drives the larger gear which is connected to each axis and it was a pain to print right. I needed two of them for the project but in the end printed 7 of them. Here are the 5 failures + one of the good ones. IMG_3518 So going from left to right, here is what I learnt from printing each part and the setting I changed till I got a usable print:

Far Left: This was my first attempt with the no support structure, which didn’t take me too long to realise was a mistake as the part started to have issues with overhangs as soon as the print reached the gear section, after which I stopped the print early.

2nd and 3rd from the Left: These were both printed with the same settings. After the first print I added some support material between the parts of the gear thread which worked just fine, except that the slicer (Cura) also added support material in the keyed shaft which was near impossible to remove (you can see my attempt to remove it on the 3rd part.

4th and 5th from the Left: To solve the issue of the slicer I decided to rotate the part by 180 degrees and have it print upside down. This actually worked really well and afterwards I was able to get a really clean looking gear that went onto the stepper motor well. So in I did a fit test with it and connected it to a bearing (which is the round thing) and, well, it got stuck and long story short I broke it. Probably not too surprising since I was printing with 30% infill but still unfortunate. The second part I printed with these setting also fell victim to destruction, this time while i was removing  the support material. I decided it was time to change blades on my knife I was using to remove the material and while working on the piece with the new blade managed to cut straight through it.

Final Print: Learning from my prior mistakes I set the infill for this print to 100% and it turned out very well with no issues.  Hooray! I then too extra care to not repeat cutting through the piece when removing the support material.

Through this process of iterative printing I learnt a lot about the factors that go into a successful print and the importance of orienting each part for optimal printing. Now that I have all that parts done the next step is to start assembling the ground station which will come in the next post of this series!

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