A question for @DavecUK and anyone else who may have played with non-stock burrs.
I’ve had success with the 3 SSP burrs and the k151H in the Duo.
But others have not ground fine enough for light roast espresso even at the point of chirp.
Following Dave’s lead I’ve used a micrometer and measured the thickness of each burr set at three points. I repeated that three times (a total of nine measures), re-measured any outliers and then averaged the measurements.
Repeat that for 16 × 83mm burr sets.
The common demoninator for burrs that work in the Duo for espresso is that they are thicker than the stock Mazzer 151B espresso burrs.
Every burr set that is thinner, (even as little as 0.033 thinner) won’t grind fine enough for light roast espresso.
Today I tried shimming a set of DF DLC burrs (one of the thinner sets). By my calculations a shim of 0.1mm would have been enough, but so much for my calculutions. I kept adding another 0.1mm to each shim and ended up with an additional 0.5mm but each additional shim seemed to make no difference at all to the grind size. (I added 0.3 to the bottom burr and 0.2 to the top burr).
My question is: has anyone had success in shimming thinner burrr sets? Or is there another method? Or should I simply accept that burrs any thinner than the 151B simply won’t grind fine enough for espresso?
Plan B is to wait for the DF83V. Given the stock burr is likely to be thinner than the 151B (it will be the 83mm DF DLC burr that I mentioned above) some of the burrs that won’t fit the Duo because they are too thin, may fit the DF83V.
_A reminder about why I’m doing all of this: in March I want to run a Burrnament, like a Tournament except with burrs rather than sports teams/players. Knock out rounds, finals, champion burr. Parameters and protocols still being sorted but blind taste tests for sure, mitigation of variables too, and the finals will likely involved mutliple judges.
To date I have 31 burrs in ready to go (16× 83mm and 15× 64mm) and gettings grinders that will accomodate each burr set is part of the preparation. Hence my need to figure out how to get as many burrs of each type working in as few grinders as possible. If shimming would work, that would be very helpful._
