The Founding Story of Chestnut S5 Pro
We set out to build a better S3
Our starting point was simple. The TIMEMORE Chestnut S3 was our first hand grinder with external grind adjustment. It sold well. People liked it. Which, naturally, made us start wondering what was still wrong with it.
Before setting out to design the S5 Pro, we reacquainted ourselves with the S3. Looking it over, we decided to start with the burr set. One obvious move was to make the burr larger. A larger burr would give us more room to control how the beans entered the cutting geometry, reducing uncontrolled bean-to-bean collisions and improving particle distribution. But widening its diameter would also require more force to grind.
The answer to this quandary was in the pre-breaker, the blades that break apart coffee beans before they hit the main cutting teeth. It isn't that the S3 has none — it's that the pre-breaker wasn't controlled enough. In our testing, we found that beans weren't being broken up thoroughly or consistently before they reached the main cutting geometry.
And when that step is unstable, everything after it is too. A bean that hasn't been broken open gets compressed against its neighbors over a very short distance, and which bean gives way first, and how, comes down largely to chance. Chance produces fines you can't control. The same setting becomes less predictable. A good cup becomes something you found once, not something you can reliably make again.
We wanted to make that step controllable.
Three forces — only one of them is new
You might think Tri-Break sounds like a clean-sheet redesign. It isn't. It's the culmination of several years of incremental development, bringing together the three principal forces that act on a coffee bean before it reaches the main grinding geometry. Hence the name: Tri-Break.
The first is compression. Coffee is drawn into the burr and wedged between the inner and outer burr surfaces. Every burr grinder relies on compression to some degree.
The second is piercing. With our S2C geometry, we replaced a conventional flat-edged pre-breaker with serrated teeth designed to pierce the bean and guide it more deliberately toward the main cutting surfaces.
But then we got to thinking, "With a larger burr, why don't we have both kinds of teeth?"
That led us to the third force: shearing. A serrated tooth opens the bean; a flat edge cuts through it. Running both on the same burr meant we could pierce and shear in the same rotation.
Of course, adding those flat blades meant rearranging the teeth. Where the previous S2C-042-III burr used a six-point structure, the S5 Pro uses a twelve-point star, with six flat teeth added between the existing serrated S2C blades. Why not simply make them all flat? Because then there'd be nowhere for the piercing to happen. Fill the gaps with flat blades and the bean only gets compressed and cut — it never gets opened first. So they alternate: the flat teeth make room and shear what passes them, the bean falls into the gap between them, and a spike opens it there.
None of the three happens in sequence — they happen at the same instant, in the pre-breaker. The three in Tri-Break counts the ways beans are broken up, not the grinding stages.
Together, compression, piercing, and shearing give the S5 Pro a more controlled pre-break and a higher feed rate.
Where 48mm came from
The pre-breaker solved the compression problem. It also created a new one.
Beans that arrive at the main cutting geometry already broken travel through more smoothly, and the feed rate goes up with them. Keep the burr the same size and the output can't keep pace with the intake — what goes into a burr and what comes out of it have to stay in balance.
So we could finally move to 48mm.
The larger burr was first of all a way to match that higher feed rate. But it brought more than that: a greater effective grinding surface and a longer effective grinding path, and with them a tighter grind distribution.
48mm has mostly been a benchtop electric size. The larger the burr, the more beans it takes in per rotation, and the more force it takes to turn — force that usually comes from a motor.
Here the pre-breaker helped a second time. A whole bean entering the main cutting geometry has to be worked through from start to finish; fragments that have already been broken only need to be reduced. Same rotation, noticeably less torque.
So a size that belonged to a motor turned out to be something one hand can manage.
What happens in the cup
The burr changed, and so did the cup — though not in the way people often assume. The pre-breaker doesn't decide whether a coffee tastes sweeter or brighter; that comes down to the main cutting geometry and to how you brew. What it changes is the ground coffee those things have to work with.
Still, put the same beans through both grinders and you'll taste the difference.
The S3 gives you a cup with pronounced sweetness and high clarity, softer acidity, gentler definition — a light, crowd-pleasing rock sugar character that's easy to love. That same character is why espresso has never been where the S3 is most comfortable.
The S5 Pro goes somewhere else. Acidity is more defined and sits in better balance with the sweetness; there's more body, and both the layering and the definition move up a step. Espresso is noticeably easier to work with than it was on the S3.
Which is better? There's no answer to that. If what you love is a clean, transparent, sweet cup, the S3 has always done that beautifully. The S5 Pro is for people who want more structure and more to work with.
The adjustment ring, where we indulged ourselves
Beyond the burr, the second thing we rebuilt was the external adjustment ring. The S3 adjusts externally too — that part hasn't changed. What changed is how it feels in the hand.
A fair number of people at TIMEMORE are serious amateur photographers in their spare time. While we were working on this version of the ring, everyone had the same object in mind: the aperture ring on a camera lens. That sensation of each stop catching cleanly as you turn it. That certainty of knowing where you are by fingertip, without looking at a number.
The new ring was built in that direction. The detents are more defined, each click reads more clearly, and a red dot on the body marks where you are. You can look down at it, or not — your fingers can count.
The firmer resistance brings something else with it: the ring is much harder to knock out of position when you aren't using it. Throw the grinder in a bag, push it to the back of a drawer, hand it to someone to try — it comes back on the setting you left it on.
Which sounds like a small thing, right up until you lose a dial-in to a bumped ring and spend two brews working out why the coffee changed.
Finally, about the missing S4
Anyone paying attention will notice that the S3 is followed by the S5 Pro.
We did skip four. In Chinese, the word for four sounds close to the word for death, and it has long been considered unlucky — elevators in China often have no fourth floor, much as buildings in the West often have no thirteenth.
It isn't a technical decision and it doesn't affect a single bean. But enough people would rather not own a "4" that skipping it needs no further justification.
Specifications
| Product name | Chestnut S5 Pro |
| Burr set | TriB-048-I, 48mm |
| Grind settings | 90 clicks, 15 microns per step |
| Capacity | 30g |
| Weight | 910g |
| Handle | 185mm, foldable |
| Materials | Aluminium alloy, 304 stainless steel, silicone |
Frequently Asked Questions
What's the difference between the TIMEMORE S3 and S5 Pro?
The burr grows from 42mm to 48mm and uses a new Tri-Break geometry with a 12-point pre-breaker. The external dial has been redesigned: the detents are more defined, each click reads more clearly under your fingers, and the ring is much harder to knock out of position when you're not using it.
Is the TIMEMORE S5 Pro good for espresso?
Yes — noticeably more workable than the S3. The finest setting leaves a 75-micron burr gap, and the tighter particle distribution from the Tri-Break burr makes shots easier to dial in and more repeatable.
How heavy is the TIMEMORE S5 Pro?
910g. That weight is deliberate — it's where the stability comes from — but it makes the S5 Pro a home grinder rather than a travel one.
How many clicks does the S5 Pro have?
90 clicks on an external adjustment ring, 15 microns apart, with a defined detent you can count without looking.
Should I upgrade from my Chestnut S3?
The Chestnut S3 is still an excellent grinder and the dial precision is identical. Upgrade if you want more body and structure, or if you pull espresso regularly.