Setting Up Your Grinder in Grinder Manager

Worked example: the Kinu M68

Part 1: Describe your grinder

First you describe how the grinder’s dial is laid out, so CoffeeOS knows where every setting sits: its numbers, its clicks, and whether it rotates.

Three terms to know first

Numbers: the whole steps, the figures printed on the grinder itself. Some grinders have only numbers.
Clicks: the lines or partial steps between the whole numbers. Every setting moves forward one click, so the total number of clicks is the same as your total positions. Type a click count into the tool and it works out the matching setting, how many rotations and numbers, and takes you there.
Rotations: whether the dial travels past its last number and keeps going. If the dial hits a hard stop and never comes back around, it has no rotations, and every setting is written with two parts, Numbers and Clicks. Some grinders use all three.

Annotated Kinu M68 dial showing numbers, clicks, start number and highest number — The Kinu M68 dial: the whole numbers, the click lines between them, where the scale starts, and its highest labeled number.

1. Create or select a grinder

Open Grinder Manager
Tap the menu at the top
Choose Template or Blank grinder
If your grinder already exists in CoffeeOS, select it from Template
If not, tap Blank grinder

Grinder Manager menu with Blank grinder highlighted — Open the menu and choose Blank grinder to build a new type.

Grinder Manager supports multiple instances of the same grinder model. Here, we are setting up a new grinder type. You will name individual grinders later. In this example, we are adding the Kinu M68.

Enter the grinder model name
Example: Kinu M68

Naming the grinder type KinuM68 — Name the grinder type.

This name refers to the grinder type, not a specific physical grinder. You will be able to name individual grinders (e.g. Kinu M68 Shop or Kinu M68 Home) later.

2. Define the numbering system

Select whether the grinder starts at 0 or 1
In our case, it starts at 0
Identify the highest labeled number on the dial
For the Kinu M68, this is 9

Close-up of the Kinu M68 adjustment dial — Read the starting number and the highest labeled number straight off the physical dial.

Entering Max Number as 9 — Enter the highest labeled number as Max Number (9).

3. Define clicks between numbers

Check whether there are clicks or lines between whole numbers
These are usually smaller lines between the larger numbered marks
The Kinu M68 has 4 clicks between each whole number

Turning Clicks on and setting Clicks Between to 4 — Turn Clicks on and set Clicks Between to 4.

4. Determine rotation behavior

Some grinders:

Have a hard stop just before 0
Stop randomly after several rotations
Or, like the Kinu M68, keep turning until the burrs fall out

If your grinder keeps rotating, you must decide what the coarsest usable grind setting is.

In my case, grind particles became unreasonably large at 3 full rotations, 5 numbers, 0 clicks
I defined that point as the coarsest setting

Omni and the particle analysis coaster register particles up to 2500 microns. Anything larger reads as noise and is ignored, so there is no value in measuring past it. On a grinder with no end stop, keep opening the grind coarser and testing until the particles are so large you would not reasonably use them even for cold brew, and treat that point as your coarsest setting.

A usable coarse grind next to a grind that is too coarse — A grind you would still brew, next to one that has gone past useful. When the particles look like the right-hand pile, you have found the coarse end.

5. Enter total grind positions

Under Rotations, enter the total number of usable positions so CoffeeOS knows where the grinder should stop.

For this grinder, that value is 175 positions

Entering Total Positions as 175 — Enter Total Positions (175).

Total positions is simply the total number of clicks from your finest setting to your coarsest. Here is how that reaches 175 on the Kinu M68, and how the midpoint maps back to a real setting.

Diagram of how rotations, numbers and clicks add up to 175 positions — Counting positions on the Kinu M68, and finding the middle setting.

The rotations, numbers and clicks wheel selector — Set rotations, numbers, and clicks on the wheel to jump to any position. Typing a click count into the Tool Controller does the same thing.

Part 2: Measure the grind curve

With the grinder described, you measure a few grind settings to build its particle-size curve, then let CoffeeOS fill in the rest.

Measuring the grinder curve

To get the most accurate grinder curve, measure particle size as precisely as possible.

Because particle sizes vary, we use D50:

The point where 50% of particles are larger and 50% are smaller

If all of your measurements are done inside the Particle Analyzer, pressing Done will automatically populate the final D50 value for you.

6. Measure particle size

Starting with the finest setting:

Use DiFluid Omni or a particle analysis coaster
Grind one whole coffee bean
Measure everything that comes out of the grinder, fines and larger particles alike, so you capture the full distribution

Particle Analyzer with the Add Test button — In the Particle Analyzer, tap Add Test to take a reading. The counter tracks how many tests you have added.

How many tests, and why

A single test gives you a quick read on the shape of the distribution, and if your sample is well mixed you will see a sensible spread of particles. The catch is that one test does not capture the full distribution, so its D50 can sit well off the true value. Each additional test tightens the result. For grinder setup, aim for about 10 tests per setting.

Grind enough coffee to cover 10 distinct tests. Measuring the whole of one bean took 11 tests in this example. A grinder that holds several grams in retention will need more coffee ground before you begin.

If you use Omni, keep each test light on coffee. Check the surface of the analysis unit after every test and confirm the particles are spread evenly. Visible clumps push that reading’s D50 higher than it should be. For espresso, break up the clumps with a brush and skip the auto dispersion feature. For very coarse grinds, make sure the large particles are not flung to the edges and out of view, which would leave only the fines in the frame. Omni’s auto dispersion is at its best from medium fine through medium coarse.

Omni auto dispersion spreading grounds across the base — Omni’s auto dispersion spreads the grounds evenly across the base before it measures. Check for clumps after every test.

Omni or the coaster

You do not need Omni for this. The DiFluid particle analysis coaster works just as well: spread the grounds evenly across the coaster, run the Particle Analyzer the same way, and read the same D50. Take about 10 tests per setting on the coaster too.

Particle analysis coaster with dispersed grounds being measured by CoffeeOS — The particle analysis coaster in use: grounds dispersed across the surface, measured with the Particle Analyzer in CoffeeOS.

Record each setting

Finest setting particle distribution result, D50 274 microns — Finest setting result (M68 0,0,0). Record the D50 (274 µm).

The Finest Grind field where the D50 is stored — The Finest Grind field, where the finest setting’s D50 is stored.

Repeat this process for:

Middle setting, position 88

Middle setting particle distribution result, D50 664 microns — Middle setting result (M68 1,7,3). Record the D50 (664 µm).

Coarsest setting, position 175 (3 rotations, 5 numbers, 0 clicks)

Coarsest setting particle distribution result, D50 1083 microns — Coarsest setting result (M68 3,5,0). Record the D50 (1083 µm).

7. Finish setup

Press Done
Your grinder is now set up
Tap Curve to view the grinder’s particle size curve

The finished grind-to-particle-size curve — The grind-to-particle-size curve. This example was filled in over many measured settings, not just the three in this walkthrough.

More points make a truer curve. Coffee does not break evenly as you open the grind, so the real line bends between settings rather than running straight. The three measurements above give you a usable curve right away; each extra setting you measure pins down one of those bends.

Expand the Tool Controller at the bottom to step through every setting and read its particle size.

Tool Controller listing each grind setting and its particle size — The Tool Controller lists each grind setting and its measured particle size.

Using the grinder data

You can now use this grinder in the Grinder Converter tool
This allows you to match equivalent grind settings across different grinders

The grinder listed in the Grind Converter Grinder Manager tab — The grinder appears in the Grind Converter’s Grinder Manager tab, alongside your other grinders.

For higher accuracy

Measure additional grind settings
The more data points you add, the better the curve

Once you have measured several points, tap Auto Update in the Tool Controller at the bottom of the curve view. CoffeeOS recalculates the surrounding settings for you, so you do not have to measure every position by hand.

Auto Update button in the Tool Controller — Auto Update now sits in the Tool Controller at the bottom of the screen.

Auto Update can only fill the gaps when your measured points climb in order from finest to coarsest.

Measure one ordinary coffee throughout. Different beans and roast levels have different densities and fracture differently, which would distort the curve. If you want very high precision, set up a separate grinder profile for each roast level and density you grind, since those change the distribution too.

The order has to make sense. If a finer setting reads 235 microns and a slightly coarser setting a few clicks along reads 230 microns, the values move backwards, and Auto Update cannot calculate the gap between them.

This setup gives you a functional curve immediately, with the option to refine it over time.

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