Zerno Z1: Frequently Asked Questions

General usage

I’m having trouble adjusting the grind finer with the grinder off.

Do not adjust finer with the grinder turned off. Always switch it on before making finer adjustments to avoid coffee particles becoming trapped between the burrs. See this video for guidance. You can adjust coarser with the grinder off if you so desire.

How can I manage retention and exchange when grinding?

When grinding fine for espresso, some grounds may retain inside. To release them, give the funnel a firm tap with your palm. Flick the chute a few times as well, but hold it steady to prevent it from falling into the catch cup. See this video by Vel.

How do I know if my Z1 has a ionizer? Why was one not included?

Initial batches included a ionizer beneath the stationary burr, but the new chute design removes the need for one, so ionizers are no longer included in newer units.

Why are beans getting stuck before reaching the burrs? I’m using $number RDT sprays to reduce static.

To reduce static without causing bean clumping, use only one or two RDT sprays. Some older Z1 batches were equipped with a non-toothed pre-breaker that occasionally retained beans. The Zerno store now offers a V2 medium-speed auger with a toothed design to address this issue.

What grind setting should I be using for X and Y with burrs Z?

See this spreadsheet for settings used by other owners. Generally speaking:

  • Espresso: anywhere between 50 and 200µm depending on the burr. Most likely 125 to 200µm
  • Filter: most likely 500 to 700µm, with 600µm as a good starting point

Why can’t I find a set screw for my funnel?

The funnel does not require set screws.

How do I swap augers? I’d like to try the Slow-Feeding auger but I have no idea where to start

Swapping augers is a bit more involved than swapping blind burrs and requires the use of the provided tools. For a detailed guide, refer to this video by Vel. If you find yourself swapping augers frequently, consider reaching out to the Customer Service to purchase a “Z1 Prebreaker assembly” with “Prebreaker auger screws.” This will allow you to permanently mount a slow auger to a rotary carrier plate, making hot-swapping a breeze.

Burrs, zeroing, and alignment

How do I remove the stationary and rotary burrs, and where can I find the magnets?

See this video by Vel. To remove the stationary burr, use the two small magnets provided in the box. They look like small, rounded handles. Place the magnets on opposite sides of the stationary burr’s face, and rock them gently; this should loosen the burr enough to pull it out. For the rotary burr, firmly tap the auger against the palm of your hand to release it.

The stationary burr is stuck!

Sometimes, the stationary burr can get stuck after seasoning or grinding espresso for a while without switching them out. Don’t worry, it happens to everyone! Here are a couple of ways to fix it:

  1. Grab the two magnets and put them on the same side next to each other. Gently pull them toward you and then let them go. Repeat this process until the coffee particles loosen and the burr breaks free.

  2. If the burr is still stuck, use a pair of soft gloves to wiggle it axially (try to rotate it left and right). Then, use the magnets as in step 1.

Why does my unit not have radial screws for the blind burrs?

Radial screws were phased out starting with batch 5, so they are no longer needed or included in the newer models.

Positioning the Stationary / Top and Rotary / Bottom burrs

Most burrs don’t require a specific placement (like rotary vs. stationary) because their geometries are mirrored. However, some burrs (HU and CV3) have different geometries and can be installed as recommended by SSP. In the Z1, “stationary” or “top” burrs should be installed on the grinder’s body, while “rotary” or “bottom” burrs should be placed in the rotary carrier.

Seasoning

The necessity for seasoning is debated, and “how much” can vary depending on burr type and its coating. Generally speaking:

  • SSP MPv1 / Unimodal / “Brew” with Silver Knight coating (silver color): up to 5-7 kg (10-15 lbs)
  • SSP MPv1 / Unimodal / “Brew” with Red Speed coating (orange): 2-3 kg (4-5 lbs)
  • SSP MPv2 / Unimodal Espresso / “Multipurpose” with Red Speed coating (orange): 2-3 kg (4-5 lbs)
  • SSP HU / “High Uniformity” with Red Speed coating (orange): 2-3 kg (4-5 lbs)
  • SSP CV2 / “Cast V2” / “Lab Sweet” with Silver Knight coating: up to 5-7 kg (12-15 lbs)
  • SSP CV3 / “Cast V3” / “Lab Sweet” with Red Speed coating: likely 2-3kg (4-5 lbs)

The coating seems to account for the largest difference. Silver Knight Casts seem to benefit from the largest amount of seasoning.

Installing Burrs with Regular Mounts

See this video by Vel. Use the screws from the accessory bag included with your unit, and the two foam pads. You should find all of that in the “goodie bag” that also containins spare parts such as burr screws, an Allen key, spare fuse, and SSP certificates.

What is the purpose of the foam inserts?

The foam inserts are intended for regular (non-blind) burrs (see above), and prevent coffee grounds from building up behind the burrs. Place these inserts between the burr and the grinder body (or carrier) to prevent coffee particles from collecting behind the burrs.

Carrier / Auger positioning

When inserting the rotary carrier/auger, ensure proper alignment. If the auger touches the stationary burr with light pressure, it’s correctly aligned. If it requires force, rotate the auger until it clicks, sinks onto the shaft, and engages properly.

What is the “chirp-to-lock” measurement, and how do I optimize it?

The “chirp-to-lock” refers to the difference in microns on the adjustment dial between two points:

  • The “chirp” point – where the burrs first make contact, producing a characteristic sound. (see this video for “false chirp” vs “real chirp”)
  • The lock point – where the burrs fully touch and lock with the grinder powered off.

This measurement typically ranges from 5 to 50 microns and depends on how tightly the collar is secured past the chirp point.

However, the “chirp-to-lock” distance may vary based on the orientation of the keyed auger on the grinder shaft. To achieve the best alignment:

  1. Follow the steps described previously to lock the keyed auger onto the shaft properly, reassemble the front dial, and determine your current “chirp-to-lock” distance after zeroing the grinder.
  2. Flip the keyed auger 180 degrees and measure the “chirp-to-lock” distance again.
  3. Use the auger orientation that results in the smallest “chirp-to-lock” measurement for optimal alignment.

My zero point seems off. What can I do?

If the burrs chirp, it may indicate either contact between the burrs or trapped coffee particles. The chirp sounds different in each case; refer to this video for guidance.

Is the grinder “permanently aligned”?

The grinder’s alignment is maintained by the middle section, which extends from the metal stand to just behind the bean opening. Provided the burr surfaces are perfectly flat, this design ensures the grinder remains permanently aligned as long as the middle section remains untouched.

The following components can be disassembled, removed, and replaced without affecting the alignment:

And of course, the stationary and rotary burrs.

Maintenance and troubleshooting

I’m trying to remove a screw using the Zerno-branded tools that came with it, but it’s not working. The tool is spinning without applying any torque!

To fix this, you need to extend the bit of the tool and tighten the grub screw on the flat spot of the tool bit. This will lock it into the handle and allow you to use it effectively. If you have a more recent unit, you should not have any issue with the new Wera-branded hex tool.

Where can I find a diagram for lubrication and what type of lubricant should I use?

According to Vel, one component that can be optionally re-greased to mitigate potential knocking and enhance the user experience of the grinder is the slot on the main shaft where the auger key engages. It is advisable to re-grease this component when the factory grease becomes dry or is wiped off. Use Molykote 111 or a comparable food-safe lubricant for this purpose.

My Z1 makes a sound alternating in pitch

Does the sound resemble this? If so, it is possible that the Z1 is drawing power from the same power strip or outlet as your kettle, espresso machine, or another power-hungry appliance. When the kettle or machine heating element turns on, the voltage drops, causing the Z1 to slow down and produce the alternating pitch change. To resolve this issue, you can either move the Z1 to a different outlet or use it between heating cycles.

Why does my Z1 sound noisier than Will’s?

Will received a silent model.