Fun Faceted Funnel

As an avid autodidactic homeroaster, I have inflicted almost a quarter of a ton of coffee on many in our immediate circle over the past nine years. (We ourselves consumed slightly more than that in-house, so the half-ton-in-total mark was passed shortly before Christmas.)

The point is that, whether one is pouring freshly roasted beans or freshly ground coffee into a container/grinder/pot/bag, it can get tricky (i.e. messy). Normal narrow-and-long-necked kitchen funnels won't do; they block or clog instantly. For giving coffee away we often re-use wide-necked 1.5 litre polyethylene bottles - these normally take at least 500g of beans, often more, depending on the variety, terroir, and roast. Interestingly the density of (freshly) ground coffee is remarkably similar to that of the unground roasted beans, so it holds essentially the same amount of coffee in either format. But even though the neck of the container is supposedly wide, we still need help - hence the funnel, which was dimensioned to loosely fit over the outside of the thread, so that it does not bottle-neck the access any more than the neck of the bottle already does. But of course the funnel works quite well to direct coffee into other jars, the grinder, the small French press, the Bialetti moka pot, and even into bags, as and when needed. I use it a lot. Every house needs a wide-necked funnel, in fact.

Designed in FreeCad and a jiffy: a single spline curve shaped and dragged on the TLAR* principle, then rotated around the vertical axis. The resulting solid shape was then imported into Prusaslicer, aggressively simplified to obtain the lovely faceted appearance, and then the neck was restored to a smooth round shape by using Prusaslicer to add a cylinder into it, with an OD of 40.5mm. But why 40.5mm? To fit around the 1.5l PET bottle neck we need an ID of about 38mm (one has to assume that would be one-and-a-half freedom units) to which we added 0.5mm for a easy fit, and another 2mm, because we intend to print it with a 1mm wall thickness. Sometimes, albeit not very often, I do think ahead.

Printed in 0.2mm spiral vase mode, with zero top and bottom layers, and an extrusion width of 1mm, squeezed through a normal 0.4mm nozzle. You can go even wider, but do note that the slicer attempts to maintain the outside shape/dimensions, therefore a wider extrusion will result in a smaller inside clear aperture, which may or may not matter. Judicious X-Y scaling can restore it, though.

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In Prusaslicer you can find the extrusion width settings under Print Settings|Advanced as shown above. Just set everything to 1mm, to be safe. The file BeanFunnel.3mf should also have everything configured the way I printed it, including dialing up the printing temperature by 10 or 15°C, to ensure strong layer adhesion. Even with such a wide extrusion, spiral vase prints are still, by definition, single-walled, so you can use all the strength you can get. Doing this we get a lot. When spiral-vasing, go wide and warm for the win.

Use PLA or PETG - both should work just fine. No supports, and I did not need a brim, but YMMV.

* TLAR = That Looks About Right