First Aid: Grinders & Scales

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Grinders are the underrated workhorses of your setup — and most «defects» are cleaning, zero point, or simply new beans. Here are the most common problems with grinders and barista scales, with safe steps according to manufacturer guidance: Varia, Weber Workshops, Comandante, Option-O, Eureka and Acaia.

1. «The espresso suddenly comes out completely different from yesterday»

Most common reason: new or older beans — not a defect.

Try this first:

1. Check bean age: freshly roasted needs finer, older needs coarser.
2. Adjust the grind size in small steps — one change per attempt, going by weight and taste.
3. Note the reference value per bean (clicks/dial).
4. Clear fines from the outlet and chamber with a brush and bellows.

Sources: Comandante — FAQ · Varia — VS3 Manual (PDF)

Stop line: No disassembling "on suspicion", no work on the motor.

Go deeper: Grinder Lab · Gear: brush & bellows in Grinder Accessories

2. «The grinder is clogged — almost nothing comes out, then clumps»

1. Unplug it, empty the bean hopper.
2. Clear the outlet chute from the outside with a brush and vacuum cleaner.
3. Varia: check whether the setting is in the locked 0–1 range — set it coarser.
4. Operate the bellows several times, start a test grind coarser, then step by step finer.

Source: Varia — VS3 Manual ("blocked grind chamber") · Video: Varia — VS3 Gen 2 Deep Cleaning (official channel) · Urnex — Grindz: How to Clean a Coffee Grinder · Eureka doesn't publicly document this — our steps apply analogously; if in doubt, get in touch.

Stop line: Anything on the Eureka grind chamber beyond accessible chute cleaning = a service case.

Gear: brushes from the cleaning range · Burr cleaner: Urnex Grindz (not for super-automatic grinders with a brew chamber)

3. «After cleaning, none of the settings are right any more»

1. Varia: turn the hopper clockwise as far as it goes past "0", then back to "0" — that's the new zero point.
2. Comandante: zero = the first setting where the horizontally held crank no longer falls on its own; count clicks from there.
3. Option-O: after a burr change, carry out the zero calibration according to the official video.
4. Note the new reference values — the first few grinds are a settling-in phase.

Sources: Varia — Manual (calibration) · Option-O — User Guides · Videos: Varia — VS3 Gen 2 Calibration · Option-O — P80 Zero Calibration

Stop line: No disassembly beyond the manual's steps (bearing seat, motor shaft); never force the burr carrier into alignment.

4. «The dose fluctuates — old leftovers from yesterday come out with it»

1. Operate the bellows after every grind — that's part of the single-dose workflow.
2. Weber EG-1: remove the magnetic caps, wipe out the grind chamber — according to Weber a 30-second routine, ideally at every bean change.
3. Weekly, brush and vacuum the outlet and chamber.
4. Compare the weight in and weight out (e.g. 18 g in → 18 g out).

Sources: Weber Workshops — EG-1 Cleaning · Weber — KEY Manual · Video: Weber — EG-1 Daily Cleaning (official channel)

Stop line: The wiper system and bearings only as far as the magnetic-cap opening; electrics are off-limits.

Gear: dosing cups & bellows in Barista Accessories · Puck Prep Workshop

5. «Coffee flies everywhere and clings to the cup» (static)

From our own practice — hardly any manufacturer documents this officially:

1. RDT: 1–2 drops of water on the beans before grinding — via a spray bottle or a damp spoon back. Never spray into a running grinder.
2. Use a metal catch cup instead of plastic.
3. Let the cup sit briefly after grinding, then tap it.
4. Clean the outlet regularly — fines increase static. Dry winter air in Swiss indoor spaces makes it worse.

Stop line: No water in the container or chamber, no anti-static modifications to the electrics.

Gear: metal dosing cups (Varia/Normcore) in Barista Accessories

6. «The grinder no longer starts — or stops mid-grind»

1. Switch off immediately, unplug it, remove the beans.
2. Only open the grind chamber via the officially approved route (Varia: manual, disassembly section) and remove foreign objects — usually a small stone.
3. Vacuum the chamber, choose a coarser setting, test again.
4. Check the outlet and cable against another device.
5. If the motor still won't start: service — don't keep trying.

Source: Varia — Manual (foreign material)

Absolute limit: Motor, capacitor, circuit board, power supply — never yourself. In the case of stone damage, we check the burrs at the same time.

Request service & repairs

7. «My Comandante turns hard, grinds roughly — or the clicks confuse me»

1. With daily use, disassemble weekly and clean with a brush/compressed air — explicitly intended by the manufacturer.
2. Rinsing with water is allowed — but never soak it, never use a dishwasher, dry all parts completely. Never clean the Ironheart steel burr set wet (it's not stainless).
3. Determine the zero point: hold the grinder horizontally — the first setting where the crank no longer falls; count clicks from there.
4. A slight amount of play at the top of the crank is by design — not a defect.

Source: Comandante — FAQ · Video: Comandante — How-To Care & Clean C40 (official channel)

Stop line: Never oil or grease the axle and bearing; a bent axle = service.

Spare parts & Red Clix: Comandante Accessories · Hand Grinders

8. «The Acaia won't connect to the app — or the firmware update is stuck»

1. Switch on the scale, update the app and the smartphone's system.
2. Close all other coffee apps — the scale only holds one Bluetooth connection.
3. Android: enable location services; switch Bluetooth off and back on, keep the phone close to the scale.
4. Stuck update: close the updater app, disconnect and reconnect USB power, do a soft reset, restart the update.

Sources: Acaia — Scale doesn't connect · Acaia — Firmware update failed

Stop line: Never open the scale.

9. «The Acaia switches off mid-shot — or doesn't charge properly»

1. Adjust the sleep/auto-off timer in the settings or via the app (Lunar: 5 to 60 minutes, or off).
2. Check the charging indicator (Lunar: lightning bolt icon bottom left; Pearl S: orange lightning bolt top left).
3. Test the cable on another device — faulty cables are the most common cause.
4. Let a hot scale cool down first — the charge protection blocks charging when it's warm.
5. Charge the battery fully occasionally, don't store it empty for months.

Sources: Acaia — Lunar Manual (German, PDF) · Acaia — Charging

Stop line: Don't replace the battery yourself, don't open the housing.

Scales & accessories: Barista Scales

10. «The display jumps or drifts — the scale isn't weighing accurately any more»

1. Place it on a stable, level, vibration-free surface; eliminate drafts and fans.
2. Lunar: check the base alignment — loosen the hex screws slightly, create an even gap between the base and the tray.
3. Pearl: remove trapped packing-foam residue between the base and housing.
4. Calibrate: weigh-only mode, press the T button 6–7 times quickly until "CAL", place a 100 g calibration weight centred on the scale.

Sources: Acaia — Numbers jumping · Acaia — Calibration guide · Video: Acaia — Pearl S Smart Calibration (official channel)

Stop line: Never touch or adjust the load cell; after a drop or overload = support.

11. «Which RPM setting should I choose on the Varia VS4?»

The VS4 doesn't have a stepless speed dial, but four fixed settings (150/200/250/300 RPM). 200 RPM is a good starting point — but in the end your taste decides, not the number on the dial.

1. Start at 200 RPM as a baseline for most coffees.
2. If you're grinding light, light roasts, switch to 150 RPM — this reduces heat input and static and brings out more aromatic clarity.
3. If you want to grind faster or a coarser grind size, choose 300 RPM.
4. Feel free to experiment across the four settings. The RPM choice affects speed, heat and static — your espresso in the cup decides which setting is right for you.

Source: Varia — VS4 User Manual

Stop line: If the grinder repeatedly stops mid-grind at a particular setting for no apparent reason, don't keep experimenting endlessly — contact Varia support.

12. «Which speed (RPM) suits my burr set on the Varia VS6?»

Flat and conical burrs need different speed ranges: flat runs faster, conical slower. With very dense or underdeveloped beans, a higher RPM setting can prevent a cut-out at 500 RPM.

1. With the flat burr: start at 800–1200 RPM.
2. With the 63 mm conical burr: choose a lower setting, 500–800 RPM — this delivers better results.
3. If the grinder stops at 500 RPM or shows an error, try a higher RPM setting. That's the built-in overheating protection (PTC) kicking in with very dense or underdeveloped beans.
4. Move within these ranges to suit your taste — the RPM number is a starting point, not the goal.

Source: Varia — official FAQ

Stop line: If a higher RPM setting doesn't help either and the grinder keeps stopping, don't keep experimenting endlessly — get in touch with Varia support.

13. «The Varia EVO Hybrid no longer grinds fine enough for espresso — what should I do?»

Usually the lock nut on the conical burr has loosened and the lower burr has shifted slightly outward. This can be corrected by hand without a toolbox.

1. Attach the hand crank or motor head on top so the shaft is fixed.
2. Remove the catch cup and check the lock nut at the base of the conical burr.
3. Loosen the nut slightly, push the lower burr inward and turn it until it seats noticeably.
4. Hold the burr pressed in this position and tighten the nut firmly again.

Source: Varia — official FAQ

Stop line: If the nut doesn't loosen easily or the burr jams, don't use force — contact Varia support instead.

14. «My Varia AKU scale shows an incorrect weight — how do I calibrate it?»

A noticeable measurement error can be fixed yourself on all three AKU models using the built-in calibration function — all you need is a 100 g reference weight.

1. Place the scale on a level, stable surface and zero it.
2. On the AKU and AKU mini: press the tare button 6 times to open the calibration mode, then choose the matching capacity.
3. Place a 100 g calibration weight centred on the scale and wait until "PASS" appears.
4. On the AKU PRO: instead, hold the power button to start the calibration and follow the instructions on the display.

Source: Varia — AKU Scale User Manual · Varia — AKU PRO Scale User Manual

Stop line: If "PASS" doesn't appear even after several attempts, don't keep calibrating on your own — contact Varia support instead.

Order number: #
Device (brand + model):
Serial number (see rating plate):
Purchased on:
Problem since:

What exactly happens:

What I've already tried (steps from the First Aid page):

Attachments: photo of rating plate / photo or video of the problem

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