The Shop Grinder for Espresso and Filter
A Shop Grinder
In recent years, grinders that were developed for more industrial or supermarket applications (or even as high volume spice grinders) have been re-deployed as hybrid coffee grinders. This has allowed cafes to operate their entire service (filter, espresso and bag grinding) with just the one grinder. This has allowed cafes to offer a diverse range of coffees but comes with one significant drawback: it is a much more labour intensive system to use in a busy coffee shop, usually requiring baristas to manually pre-portion doses.
Most grinders in this class have a vertical grinding system (the blades are upright) promoting a low retention of grinds within the grinder itself — less than 1g of grind retention is achievable with this design. This allows baristas to switch between decaf, guest espressos, retail or batch brew coffee, each with a different grind setting, without worrying about purging large quantities of grinds from the throat and barrel. Other espresso grinders will retain up to 90g of coffee grinds, either in the burrs, the grind chamber, or the throat where coffee exits the grinder.
When a grinder performs well in this class, you see a significant drop in boulder production (oversized grinds) helping contribute to an appealing balance for extractions above and beyond 22% extraction yield. The geometry of the blades on the best bag grinder design produces what’s considered to be the most modal grind size distribution of any burr grinder on the market. The more modal the grind size distribution, the higher the target extraction yield — the variance between sizes of boulders and fines has been lowered, while increasing the homogeneity of those particles. For this style of grinder, we suggest the 18–22% target should shift over to 20–24% extraction yield.