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Diy Decibel Meter: Moon

My colleague and I had the idea of having some sort of decibel meter in our classrooms. We have seen one shaped as a moon and being able to display various colours.

I then immediately had the idea to create such a decibel meter myself using an Arduino, some electronics and 3d printing.

3D Printing

I wanted the moon to be modelled after the real moon of the earth, so I went to the NASA website in search of some 3d models. They actually provided such models and happy me downloaded them right away.

Though the disappointment was huge as I realised, that these models where just high resolution photographs rendered onto a sphere.

So I started to search for actual models usable for 3d printing and found one on thingiverse.com. The creator stated, that he probably took the images he rendered the 3d model from of the NASA website as well. This claim was good enough for me and I took his .stl file.

In the prusa slicer software I then cut the model in half, reduced its size to 75% (d ~ 150 mm), inserted a hollow sphere with 6 mm less diameter and sliced it using automatically generated, organic supports.

Then I started to figgle with my 3d printer. I had to do some calibrations and ajustments to get it into printing. The things I now can recommend for anyone trying to 3d print stuff are:

These things helped me to get the PLA filament to actually stick to the printing bed without loosening up.

blender hollowing

  1. import .stl
  2. hit z+4 (wireframe)
  3. Add Modifier > Generate > Solidify
  4. Set Thickness to 1 Meter (maybe go up to 1.5 Meters)
  5. Edit Mode, Select Faces
  6. Select and delete all bottom faces (this step may be simplyfied by just subtracting a cylinder (also gives larger glueing area))
  7. Export .stl

Created one with 1.5m thickness and set Normals > Flip to true In slicer subtracted a 130x130 mm cylinder from the base plate

Electronics

Material needed:

Still figuring out stuff.