In January, we traveled back to Shenzhen to continue refining MOMENTEM — not to rush production, but to make sure the grinder behaves exactly the way we believe it should.
This trip was focused on one thing: testing. Not casual testing, not quick checks, but systematic, repeatable experiments to understand how MOMENTEM’s dual-burr system behaves across real brewing scenarios.
By the end of the trip, we completed more than 40 different grinding tests, covering filter and espresso ranges, different burr interactions, and multiple adjustment strategies. What we learned gave us both confidence — and clarity.
What We Mean by Dynamic Grinding
Most grinders work in a very simple way: you adjust grind size, and the grind profile is fixed. If you want to change the taste, you go finer or coarser and accept everything that comes with that change.
MOMENTEM was designed with a different idea in mind.
With a dual-burr system, MOMENTEM separates grinding into two stages:
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The bottom burr defines the target grind size
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The top burr (pre-breaking burr) conditions the beans before final grinding
This allows us to do something a traditional single-burr grinder cannot: lock the target grind size and reshape the particle distribution around it.
We call this approach dynamic grinding.
Dynamic grinding is not about making coffee finer or coarser. It’s about tuning how coffee extracts — adjusting the balance between fines, core particles, and boulders to influence clarity, body, and mouthfeel in the cup.
Visualizing Dynamic Grinding
During our Shenzhen tests, we used professional particle analysis equipment to study how different burr interactions affect grind profiles.
One simple comparison tells the story clearly.
In the chart below, you see two grind profiles produced at the same target grind size, using the same coffee, but with different pre-breaking settings.
The peak sits in roughly the same place — meaning the grind size is similar — but the shape of the distribution changes. That difference in shape is what leads to different taste expressions in the cup, even when brew recipes remain unchanged.
This is dynamic grinding in practice.
These two profiles represent just two settings. With two burrs and multiple clicks per rotation, MOMENTEM can create hundreds of different grind profiles at the same grind size. What you see here is only a small example.
All tests shown here were conducted using Med-Light Roast – Ethiopia G1 Washed Yirgacheffe.
What We Learned From Our Tests
Looking across all our test data, several clear patterns emerged.
1. The Bottom Burr Sets the Size
When the bottom burr is fixed, the final grind size stays stable — even when the top burr is adjusted across a wide range.
This confirms an important design principle: the bottom burr acts as a size anchor, not just another grinder in series.
For users, this means fewer variables to fight with. You don’t need to re-dial everything just to explore different taste profiles.
2. The Top Burr Shapes the Distribution
With the bottom burr fixed, adjusting the top pre-breaking burr doesn’t dramatically change grind size. Instead, it reshapes the distribution:
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Reducing or increasing fines
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Tightening or widening the particle spread
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Changing how evenly coffee extracts
This is where MOMENTEM becomes a tool for taste tuning, not just grind adjustment.
3. There Is a Sweet Spot — Not “More Is Better”
One important discovery was that pre-breaking has a saturation point.
At moderate settings, the top burr improves uniformity. But pushing it too far can introduce over-fracturing, especially with certain bean sizes.
This reinforced a core belief for us: good design is about control and balance, not maximum aggression.
4. Espresso Plays by Different Rules
Our espresso-focused tests confirmed something we believe in strongly: espresso grinding is fundamentally bottom-burr dominated.
At very fine settings, physics takes over. The top burr cannot magically eliminate fines — and it shouldn’t try to.
What pre-breaking can do for espresso is improve:
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Grinding feel and effort
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Shot-to-shot consistency
One Small Issue We Found — and Why We’re Fixing It Now
Thorough testing doesn’t just confirm what works — it also reveals what needs improvement. During extended use, we identified one specific issue with the latest top pre-breaking burr prototype.
In this version, additional internal spines were added to the inner conical burr. While this helped certain aspects of pre-breaking, it slightly reduced the space that guides whole beans toward the grinding teeth. With very large beans, the last one or two beans could occasionally rest on top of the burr instead of feeding smoothly.
This was the only issue we found in the latest prototype. We chose to redesign the top pre-breaking burr, both inner and outer components, to improve bean feeding while preserving the performance we’re happy with.
What Happens Next
While the top burr is being refined, we can move forward with producing other components that are not affected by this change.
Chinese New Year is approaching, which means the factory will enter a short production pause — an unavoidable and important holiday period. As soon as the team returns, we’re ready to resume full batch production. We expect the redesigned pre-breaking burr to be done before the New Year, fingers corssed, allowing us to move forward without compromising the experience.
Why We’re Sharing This
We believe tools like MOMENTEM should earn trust — not through promises, but through process. Dynamic grinding is not a buzzword for us. It’s the result of careful design, real testing, and a willingness to slow down when something isn’t right.
Thank you for being part of this journey. We’ll continue to share what we learn, and why each decision is made — because MOMENTEM is not just something we’re building for you, but with you.
Missed the Pre-Order or Kickstarter?
If you somehow missed the pre-order or our Kickstarter campaign, don’t worry — there’s still a way to stay connected. You can email us at momentem@notabarista.org to join the waitlist. If any order is canceled or a slot opens up, we’ll reach out to the next person on the list for the upcoming MOMENTEM #3 batch.
Thank you for the continued interest and support — it truly means a lot to us.
