The periennial problem with single dosing is pop corning, that is to say because there is no weight pushing down on the beans that are being ground they are able to bounce away from the cutting face which results in an irregluar grind, which in turn produces a poor extraction
Much resource has been expended on investigating possible solutions but the only one i know of is large diameter flat burrs
In the image above is 19.4g of beans tipped into my Compak R120; see how the entire dose is effectively lying between the upper and lower burr?
When we switch on the grinder almost immediately the entire dose is thrown sideways into the cavernous space that 120mm burrs give you, and the tiny amount of popcorning that occurs for a second or so at startup in no way affects the grind because the beans at the cutting face are so far away from the open space at the spindle with so many beans between them also being thrown outwards with centrifugal force that the beans at the cutting face are unable to bounce and therefore a poor grind does not result
It is true of course that the larger the diameter of the burrs the more any inaccuracies in machining tolerances and alignment are magnified, but this is purely a quality control issue as opposed to a shortcoming of design
I simply do not see how burrs of a conventional diameter can avoid the popcorning that occurs with single dosing, and for this reason i see the forthcoming Kafatek MAX as setting a new standard in single dosing grinders for the home and my name is most certainly on the waiting list