Grind setting conversion
Eureka Atom 75 vs Rancilio Rocky
Two grinders cross-shopped at the same money. The Atom 75 turns 0–30 rotations; the Rocky is numbered 0–55.
| Atom 75 | Rocky | |
|---|---|---|
| Brand | Eureka | Rancilio |
| Scale | Rotations | Numbered dial |
| Dial range | 0.0 rotations – 30.0 rotations | 0 – 55 |
| Burrs | Flat | Flat |
| Espresso → filter | 7.5 rotations | 20 numbers |
| Filter → coarse | 20 rotations | 23 numbers |
Converting a setting
If a recipe quotes a setting for one of these grinders, read across for the equivalent on the other. Rows are spaced evenly by grind size, not by dial number — on a conical burr those are not the same thing.
| Atom 75 | Rocky |
|---|---|
| 1.5 rotations | 5 |
| 4.6 rotations | 9.4 |
| 7.1 rotations | 13.8 |
| 7.8 rotations | 17.8 |
| 8.5 rotations | 21.8 |
| 9.6 rotations | 25.7 |
| 12.7 rotations | 29 |
| 15.7 rotations | 32.3 |
| 18.8 rotations | 35.7 |
| 21.5 rotations | 38.8 |
| 24.0 rotations | 41.9 |
| 26.5 rotations | 44.9 |
| 29.0 rotations | 48 |
| Rocky | Atom 75 |
|---|---|
| 5 | 1.5 rotations |
| 9.4 | 4.6 rotations |
| 13.8 | 7.1 rotations |
| 17.8 | 7.8 rotations |
| 21.8 | 8.5 rotations |
| 25.7 | 9.6 rotations |
| 29 | 12.7 rotations |
| 32.3 | 15.7 rotations |
| 35.7 | 18.8 rotations |
| 38.8 | 21.5 rotations |
| 41.9 | 24.0 rotations |
| 44.9 | 26.5 rotations |
| 48 | 29.0 rotations |
Side by side, by brew method
Where each grinder lands for the same brew, worked out from its own dial curve.
| Method | Atom 75 | Rocky |
|---|---|---|
| Espresso | 3.3 rotations | 7.7 |
| Moka pot | 7.0 rotations | 13 |
| AeroPress (short steep) | 7.8 rotations | 17.8 |
| Pour over — V60 / cone | 8.8 rotations | 24 |
| Pour over — flat bottom | 10.8 rotations | 27 |
| Drip / batch brew | 12.7 rotations | 29 |
| Chemex | 15.6 rotations | 32.2 |
| French press | 20.6 rotations | 37.7 |
| Cold brew | 25.4 rotations | 43.6 |
The shape of each dial
Where the connectors bunch, that grinder’s dial is compressed and single steps count for more. Comparing the two shapes tells you which gives finer control, and where.
Eureka Atom 75
Rancilio Rocky
Dialing in the Atom 75
A large flat-burr espresso grinder aimed at light commercial and serious home use. Fast, and stepless in the Eureka manner — the settings here are positions to land near rather than detents to count.
Dialing in the Rocky
A stepped espresso grinder that has been the budget recommendation for a very long time. The 55 steps across 50mm flat burrs are its limitation — for espresso you will sometimes want a setting between two of them and there is not one, and a single step can move a shot by seconds. Twenty of those steps cover espresso through filter, which is more resolution than the fine end usually gets at this price. Two things make it an espresso grinder in practice rather than a general one: changing setting means holding the locking lever while twisting the hopper, and it keeps a couple of grams in the chute, so every switch between espresso and pour over costs you both fiddling and coffee. Most owners pick one end and stay there.
Own a different grinder?
Convert between any two of 78 models
The converter runs the same maths for any pair in the catalog.
Open the grind converter →Send me both charts
Every setting for the Eureka Atom 75 and the Rancilio Rocky, side by side in your inbox.
One email with both charts. Nothing else unless you ask.
Switching grinders mid-bag?
Log a brew, say how it tasted, and BrewMark tells you which way to move — in whichever grinder’s numbers you are actually using. Free on iOS.
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