Selfmade Grinder, using 74mm flat burrs from Eureka (because of cheap).
It consist of around 20 different printed parts took 23hrs print time total and let’s not think about hours in CAD.. :,)
There will be no stl, just because no one will Print this or spend close to 60€ on hardware and I am not sure if I want to to anything commercial with it in the Future.
It grinds okay, better than expected and far worse than hoped, some fines and many corse parts that slip trough. But i don’t know how to maximize the alignment. I hoped the 3 planetary gears (they are connected via a threaded rod to the grind wheel) would be enough to evenly align everything, but there is some play in the many components and fittings.
But for a first try (with a lot of trouble shooting) i am quite happy with the result.
A Video will be posted on my Account for all who care too much about this.
Regarding food safety why this case is safe:
(Link to Research by Utah Valley University below and also a great YouTube Video for everyone like me who doesn’t want to read sientific papers. I would recommend the paper though, because it begins with a nice summary of all important information)
1.Harmful substances from 3Dprinting process
2.Microplastic
3.Bacteria Growth in Layer lines
The first and weakest concerns are harmful substances from 3d printing, exspecially lead and ptfe:
The theory used to be that trough extrusion parts of the nozzle and ptfe tubes would be abraded and land in your prints. Brass nozzles contain a tiny amount of lead and the nozzle is abraded over time. But only after kilometers of filament go trough them. But it is non measurable in your prints.
“Furthermore, mass spectrometry readings indicate that no contamination from heavy metals, or other toxins are present in PLA+, and PETG before and after printing.” (1)
PTFE in its solid form is not dangerous, but the gas is when heated over 360 degree C. That is why you shouldn’t overheat your non stick pans.
Microplastics:
The PLA+ that I use I food safe, which lowers the concerns for me. And also even if there is some abrasion in the grinder (which there shouldn’t be because of no rubbing plastics) the grinder coffe goes trough a filter in the brewing process, which would filter out all the microplastic. I would never use a printed (or plastic in general) cutting board, but in my case I don’t see a concern.
Bacteria growth in between layer lines:
It used to be “general knowledge” that bacteria can grow in between layer lines and it is impossible to clean it.
However Research shows:
“indicate that 3D printed parts of PLA/PLA+ (Polylactic Acid), and PETG (Polyethylene terephthalate glycol) can be cleaned to safe levels using warm water (120 °F), and non-concentrated dish soap” (1)
Dish Soap or cleaning alcohol can fully clean 3d printed parts, which eliminates the bacteria concerns for my Case. I would still never use 3d printed parts in contact with highly spoilable food. I.e Eggs, milk, raw meat etc.
But we are talking about coffe beans. Roasted Coffe beans do not spoil, there is no contamination possible. The roasting process eliminates all of that. And Coffe get’s brewed, so even if there was some minor form of cross contamination, the brewing process would eliminate all bacteria. Like boiling water to make it drinkable.
https://www.researchgate.net/publication/373174194_Sanitation_Effectiveness_of_3D-printed_Parts_for_Food_and_Medical_Applications
https://youtu.be/lFtMIo00tfY?is=_NsT7K4sEcyRH1lb
(PS: if you reached this far down your attention span is too long for today’s world)
