I think we need to get over our tech idolatry here, and look at the facts:
- The 15/18 gram adjustment is much larger than is usual in the day to day, or coffee to coffee, tuning of an espresso grinder. Changing baskets will not change this (the adjustment range is about the same, at least for my grinder, when using kinder and gentler baskets)
- The laser sizer, when testing the same sample twice, does not show exactly same distribution. It has, like all measuring instruments, some built in variability. This variability is miniscule when measuring non-porous and nearly spherical particles. It is much worse as the particles become more porous and more irregular.
- In 15 out of 20 cases, the two very different espresso samples did not show up as more different than the same espresso sample measured and remeasured,
- Therefore, the laser sizer, when used for ground coffee, has a measurement error larger than the range used for almost all espresso adjustments.
- This fact has never been mentioned in the literature. It has also never been denied, except by implication. Either coffee labs never tried this or failed to publish the negative result
If the exact analysis shows that there is an equally large difference between the 15 and 18 gram hopper/single pairs, we will have confirmed the problem is with the laser sizer. If the SEM confirms the laser sizer was accurate, then we were massively incompetent in preparing the samples.
I'll gladly take bets the culprit is the sizer, not us; and am cheerfully willing to fleece anyone who backs the sizer.