Testing a newly arrived 3d printer and getting better tolerances out of the printer was this weeks goal. The original lid has more irregular features than a usual technical part, where geometrical forms are used and sizes seem to adhere to metric round numbers, making it harder to get it right the first time.
Printer calibration and test for the screwing portion.
Full print of the lid, fits nicely on the thermos
More tests with varying printer settings (blue: standard infill and outer layers; green: 5mm infill spacing and 1 outer layer; yellow: standard infill and 4 outer layers)
Annotations for further changes O-ring holder needs higher walls and smaller diameter; screw stop either has to get bigger or moved 2mm; gripping surface will probably loose the flat area and get completely rounded for better printability with less supports.
Three different pumps got a chance to be on this marvelous project, but only one got to prove worthy. Or something like that.
The criteria used for this part were that it had to be embedded inside the lid. All three move enough water for all practical purposes, but not all could lift liquid if the feeding tube had air inside.
My favorite was one labeled food grade on Ali. It is potted with epoxy and looks pretty solid. But this one has to be inside the water or just a few centimeters from the water level to work: This one looks already a bit shady and needs to be submerged to work, so not really a practical solution even though it was really cheap (1€).
And the last one is clunky and sounds like a tractor, but it works. At 5V it needs around 300mA, and there still flows enough water to empty the entire 2,5L in a very short time. For now, this might do: Moving forward there is room for improvement here. Maybe a peristaltic pump works well enough, maybe a 3D printed one?
It closes... almost. Might be the printer or measurement error.
Definitely measurement error... Sometimes the amazing precision of a yardstick won't cut it.
It is obvious that better suited tools were needed. ;D
The lid actually looks quite fine and it had just minor size deviations due to the not so extremely precise carpenters ruler used to get the dimensions for the first print. For a first try I think it is pretty awesome.
After a few difficulties with the printers nozzle clogging, the first iteration of the lid got printed today. It looks pretty good and very much like the original from the inside.
Next steps will include a newly designed outlet that fits the silicone tube and sensor and obtain a variable layer width by using another slicing software than cura (slic3r maybe?) to get a more robust screw, but still acceptable printing time.
The first iteration will use an existing thermally isolating container with a 3D printed lid. Almost every part of this project will be housed inside this lid, so that anyone already owning one of these popular thermal containers could add some fancy new functionality to his terere gear.
Getting the printed lid right and watertight might take a few tries, so this first attempt is just about finding out what parameters to tweak to get a perfect fit.
Clips to hold the pump and electronics are not yet included and the dispensing end has not been designed for now.
megaCell
And the last one is clunky and sounds like a tractor, but it works. At 5V it needs around 300mA, and there still flows enough water to empty the entire 2,5L in a very short time. For now, this might do:
