Lucca Atom 75 Espresso Grinder Review

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#1: Post by another_jim »

The Lucca Atom 75 is the Eureka Atom 75 customized for Clive Coffee. The line of Eureka Atom grinders is a compact version of their on-demand cafe grinders, with the Atom 75 using a 75mm flat burr. The Lucca customization includes a broken in and cyrogenically hardened burrset, a sensor based grind adjustment system that is completely repeatable, and a wifi connected database for storing the grind settings and dosing of your different coffees and prep methods.

For the past few months, Dan and I have been looking at two review grinders, provided to us at no cost by Clive Coffee; and we will be posting our impressions here. I will be looking at how good this grinder tastes (spoiler: very good), its ergonomics as an on-demand grinder (spoiler: stellar), and as a single dosing grinder (spoiler: very bad).

Here's a casual cell phone video to give you a taste ...
This topics is for review material only; please post all comments in the comment thread. Thanks.
Jim Schulman

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#2: Post by another_jim (original poster) »

Burrs and Taste

The Atom 75 uses one of the several 75mm burrs made by Eureka, and used in their 75mm grinders as well as in the Mythos line, which they manufacture. Clive coffee advertises this burr as already broken in and as cyrogenically treated, which makes it one of the premium choices normally used in the Mythos series.

In addition, the Lucca version of the grinder has an electronically measured and controlled grind setting. The new user runs the grinder in its calibration mode, tightening the grind until the burrs begin to chirp. The grinder shows this as the zero setting. This works very well. I removed the burrs several times, relaced and rezeroed them, and was able to return to my preferred settings, getting the same dose and timing. The flat panel display of the grind setting allows for very fine adjustments -- my fine espresso settings were around 40, and coarse settings were around 50.

So how do premium burrs and electronic adjustments work? Very nicely indeed. The blind comparisons done in single dose mode with five different light and medium roasted coffees were indistinguishable from the Niche Zero or other large conicals; and the "somewhat blind*" tests done in on demand mode slightly beat them.

What I cannot report is the famed flat burr effect of increased clarity and a smaller sweet for dialing in. Instead, this is one of the friendliest, sweetest, and biggest sweet spot burrs ever. That is especially true when using it in on demand mode. When the Mythos first came out, I spent an afternoon with it being seriously impressed in how fast it dialed in and how nicely it worked to fine tune the taste. Eureka has only improved on the burrs since then.

A close up look on the burr shows that there is a fairly large cut through on the outer edge. This may have something to do with the very conical taste these burrs give.

So, very fast dial in and a sweet, balanced taste yes; but the heavens open and angels sing shot clarity, no.

* Somewhat blind. In on demand mode, the hopper is on, and the grind is set on the Atom, and then I tried to get the same dose and grind on the Niche Zero. The tamping and distribution on the Atom in this mode is so effortless that getting an indistinguishable pour on the Niche was very hard. That made the shots only "somewhat blind," in that is was usually possible to guess which was which by the pour.
Jim Schulman

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#3: Post by another_jim (original poster) »

The Lucca Atom as a Single Dosing Grinder

An on-demand grinder uses a hopper filled with beans to deliver a timed or weighed dose of grounds to a waiting portafilter or basket. It can be designed to "expect" a load of hoppered beans on the intake and a mass of ground coffee inside the grind chamber output. On the other hand, a good single dosing has to work with no extra -- the coffee in either the bean intake or the ground powder output. The Atom 75 is stellar in sucking in even single beans one at a time; but its performance degrades considerably on the output side when delivering single doses of ground coffee.

The secret of the great bean intake is an augur on the burr,

and a cover over most of the burr area to prevent popcorning. There is also a rubber seal between the upper place and the burr chamber

The superb intake engineering along with the large 75mm burr makes for very fast grinding. I use a 1.2 sec setting to get a 7.5 gram single, and simply hit that twice for a double. The pace is slightly slower when not using a hopper and just feeding in a single dose; but not by much.

The grind chamber exit is a different story. There is a long tunnel after the exit, leading down behind the control panel to the portafilter or basket. There is a grate at the exit. If the grind chamber is filled with ground coffee, the coffee squeezes through the grate like whipped cream through a pastry funnel, and there is no static, just a very neat pile in the basket.

If the grate is removed and the grind chamber is kept empty by using a bellows,

the grounds are staticky and come out in a spray. They stick to the the exit tunnel and spray all over the basket and counter, requiring RDT, WDT, and other contortions. Moreover, the grind chamber retains enough loose grinds to make the dosing slightly hit or miss as well.

This is one of the easiest and joyous grinders ever to use in on-demand mode, and it is a PITA to use as a single doser. So I recommend it wholeheartedly for on demand, and don't recommend it for single dosing.
Jim Schulman

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#4: Post by HB »

another_jim wrote:Here's a casual cell phone video to give you a taste ...
Jim has thrown down the gauntlet, challenging me to make a one-handed espresso prep video. :lol:

I accept the challenge, but first I'd like to provide some backstory for the Lucca Atom 75. It's a bit market-y, but this video from Clive Coffee explains the motivation and goals of the Lucca:
As part of the Newbie Introduction to Espresso - Grinders, I demonstrated a method of dialing in a grinder by touch; dialing in a grinder is also discussed in multiple threads:
And that's just a small sample! It's clear that Clive Coffee has accurately identified a common pain point for home baristas. :shock:

The popularity of dedicated single-dosing grinders (i.e., those without a hopper designed to grind enough coffee for just a single/double espresso) has helped reduce waste because the grind setting can be changed without "carryover" from the prior setting. But that really doesn't address one of the key problems, especially for less experienced baristas: What's the best initial grind setting?

I was a bit skeptical that a "smart" coffee grinder could make a decent guess. I've tried several coffees from light-medium to dark, very freshly roasted to 2 weeks out. The estimates from the TrueGrind / Lucca Atom 75 varied from spot-on to off by a few seconds of pour time. If you want to understand how it does it, check out the patent: Coffee grinder that automatically sets grind level. It boils down to an equation:
Patent US20210219782A1 wrote:34. The method ... includes calculating the burr gap setting (G) based on the following equation:

P Offset + W Bias + (W 58Basket × P 58Basket) + (W Capp × P Capp) + (W Latte ×P Latte) + (W DoR × P DoR) + (W Dose × P Dose) + (W Temp × P Temp)
As an aside, the above formula includes temperature, but the app doesn't have that as an input parameter. It does include roast level, roast date, coffee dose weight, target extraction weight/pour time, and beverage type.
another_jim wrote:This is one of the easiest and joyous grinders ever to use in on-demand mode, and it is a PITA to use as a single doser. So I recommend it wholeheartedly for on demand, and don't recommend it for single dosing.
I agree with Jim's assessment; the Lucca Atom 75 isn't a single dose grinder designed for frequently switching coffees. Trying to coerce it into that prep model would waste coffee since you'd have to add enough extra coffee to clear out the "old" grounds from the prior coffee, plus the lack of pressure from the bean column would reduce the accuracy of the timed dosing. On the other hand, as an on-demand grinder, it's ridiculously easy to dial in.

A usage reminder: If you haven't run the grinder in awhile, I recommend tapping the "quick purge" option:

The squiggle icon runs the grinder for 0.2 seconds or about 1.5 grams of coffee.

I've been loading the hopper with 2-3 shots worth of coffee and that's enough for accurate timed dosing. I typically make 3-4 espressos a day, varying in weight from 17 grams to 20 grams if the coffee is fading, so the net loss to purging is around 3% per day. Arguably that can add up if you're buying lots of coffee, but on the other hand, if the Lucca saves you from just one sink shot a week, you're ahead of the game. It will be interesting to see how well this theoretical savings plays out in real life; it's my guess that for an inexperienced barista, the savings in sink shots/aggravation will be non-trivial.

So, who should consider the Lucca Atom 75?

It's an easy answer: If you're the type of drinker who goes through one bag of coffee at a time, the Lucca Atom 75 will fit your preparation model very well and likely save you time/aggravation dialing in when you switch to the next coffee. I suspect it's not coincidence that Clive Coffee, designer of the Lucca Atom 75, is also owner of a personalized coffee subscription service, Mistobox (disclaimer: both are site sponsors).
Dan Kehn

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#5: Post by HB »

A little late, but I'll blame the holidays! Here's a quick video that summarizes my review thoughts to-date and includes a weak attempt at Jim's "one handed espresso" challenge.
Dan Kehn

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#6: Post by RapidCoffee »

Jim and Dan have already covered many of the basics, which I will not repeat here.

Executive summary
After using this grinder daily for the past few weeks: I want one!
Great ergonomics and good grind quality (a flat burr grinder that performs like a large conical).
Not recommended for dedicated single dosers, but an excellent choice if an "on demand" grinder fits your usage pattern.

Dimensions: 7W x 9D x 17H (inches)
Weight: 21 lbs
Voltage: 110V
Watts: 900W
Burr speed: 1400 RPM
Burr size: 75mm flat burrs
Bean hopper capacity: 300g

* "on demand" grinder with small hopper
* timed dosing is reasonably accurate
* fast grinding (16-17g espresso dose in 2.5s)
* electronics provide precise digital settings for grind coarseness and time
* TrueGrind app on phone suggests grind setting for given bean
* grinder has WiFi connectivity for firmware updates, BT connectivity for TrueGrind app suggestions

* Atom 75 ergonomics are excellent. The grinder is fast, relatively quiet, clean (few grinds on counter), and kitchen friendly.

Kitchen friendly form factor of the Atom 75

* Grind quality is comparable to large conicals. Bottomless pours are "pretty", and head-to-head taste comparisons with my Mazzer Robur were inconclusive. General impressions: Atom pours are slightly more fruity, better for straight shots; Robur pours are more balanced, better for milk drinks. But this likely depends on coffee and personal taste preferences. Coffees used for testing included Klatch Belle Espresso, Black Oak Duomo, Olympia Big Truck, Red Bay Slow Burn, Oslo Odin, and several single origins.

* The Atom 75 is designed for "on demand" espresso; i.e., fill hopper with beans and grind away. This fits my usage pattern very well: open a bag of beans (typically a medium roast espresso blend) and burn through it before opening the next bag.

* The timed dosing is reasonably accurate, but not perfect. When grinding for 1.0s at grind setting 48 over a series of 10 trials, weights ranged from 7.0g to 7.4g.

* The Atom 75 can be single dosed, and the auger is very effective at preventing popcorning. However, retention is an issue. The grinder must be pulsed numerous times to expel all grinds. If you generally change beans with every extraction, a grinder designed for single dosing will fit your usage pattern better.

* Although designed for espresso, the Atom 75 also performs well with non-espresso brewing methods. I had no trouble dialing in the grinder for V60 pourovers, which had good drawdown times (~3:30") and nice separation of flavors.

* The TrueGrind app is useful, but leaves room for improvement. The app suggests a grind setting (which must be set manually) for a given coffee (if it's in the database) or roast level (if not). This generally gets you in the ballpark. Then you fine tune the grind setting and dose by trial and error, as usual. There are some quirks (e.g., minimum dose is 17g) but it's a good start.

* The 75mm flat burrs have a large sweet spot, making the grinder easy to dial in for espresso. As Jim notes, there is none of the finickiness associated with flat burrs. In fact, performance is similar to large conical grinders. You can actually see this on extraction graphs produced by the Decent DE1 (green is pressure (bar), blue is flow rate (ml/s), brown is weight rate (g/s), red is temperature (C), yellow is puck resistance). When grinders are dialed in for the same extraction time for a given coffee dose and brew ratio, the Atom 75 exhibits similar extraction characteristics to the Robur (71mm conical burrs):

Spring lever (declining pressure) profile: Atom 75 on left, Robur on right

Here are extraction curves comparing the Ultra Grinder (98mm flat burrs) to the Sette (40mm conical burrs):

Spring lever (declining pressure) profile: Ultra Grinder on left, Sette on right

The Atom 75 extraction characteristics are indistinguishable from the Robur: preinfusion, followed by a rapid rise in pressure and drop in flow rate, then a gradually increasing flow rate that flattens out towards the end of the shot. In contrast, the Ultra Grinder extraction graph shows a greater initial decrease in flow rate, followed by a greater rise in flow rate as the shot progresses (i.e., more rapid puck erosion).

This is even more pronounced with a flat 9 bar profile:

Flat 9 bar profile: Ultra Grinder on left, Sette on right

Once again, the Atom 75 extraction curve is almost identical to that of the Robur:

Flat 9 bar profile: Atom 75 on left, Robur on right

Does this observation (more rapid puck erosion for flat vs. conical burrs) generalize to other burr sets? I don't know, but it seems interesting enough to toss out for discussion.

Thanks to Clive Coffee for providing the LUCCA Atom 75 grinder for review.

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#7: Post by Jake_G »

Ive had the Lucca Atom 75 on the bench for a few days now. Here's what I've got so far.

First Impressions
When the Lucca first showed up I gave it a quick wipe down and powered it up. Being a review unit, I won't comment on packaging nor setup/instructions as this was all handled through emails and is not representative of what a new purchaser would expect to find. The first time I purged the grinder, it spun on my counter. I tipped it over and wiped the feet clean and found two centrally located suction cups in addition to grippy rubber feet at the four corners. After getting the coffee dust that had accumulated during shipping removed, the grinder literally stuck to my counter and moved no more. There was about 5g of retention in the grinder (in addition to what had rattled loose during shipping) between what was accumulated beneath the hopper and what was in the burrs/chute after them. The former I found while cleaning the grinder and the latter I found after calibrating the zero point when I poured a few ounces of Cat & Cloud's Single Origin Democratic Republic of the Congo into the home-friendly small hopper and ran a couple purge cycles. The C&C was notably lighter than the few grams of what was presumably Counter Culter's Big Trouble and the transition was obvious when the new coffee replaced the old.

User Interface
The touchscreen interface paired with a mobile app provides a modern and sleek interface for the user, if not a bit over the top. The grinder itself offers a plethora of options and menus, centered around a home screen, which displays the primary timed grind setting (set in 0.1s increments) a purge button, the selected coffee and recipe, and -perhaps most interesting- the current numerical grind setting. The options menu allows you to select your coffee and edit your coffee recipes. The setup menu has settings for calibration, wifi and other diagnostic tools. The first step after powering on was to select my wifi network and enter the passcode from the settings menu. After that, it is time to calibrate the grind position, following the menu that walks you through the process. Start the grinder, turn the grind adjustment knob until you hear the burrs just start to touch, and then hit the promp to set zero. From there, set the grind to the number that is suggested for your selected coffee and recipe. Easy peasy.

The list of selected coffees is managed through the TrueGrind App, which requires you to connect to your grinder using a unique Grinder ID number that is found in the settings menu. Once connected, you can add coffees to your library from an expansive menu or create your own. The Congo coffee from Cat & Cloud wasn't in the menu, though many other C&C options were. Adding your own coffee involves selecting a coffee name, roaster name (optional), roast date and a roast level, which is a 5 point scale from light to dark. Once your library is set, you can set up to 6 coffees to be "active", which sends them over to the grinder.

Once the grinder receives your coffees, you can select your coffee from the options menu and customize up to 3 recipes for each one. The recipe includes dose, yield and shot time. When you update or select a recipe, the grinder calculates a grind setting based on the coffee and recipe details.

Returning to the home screen, you will find your coffee name displayed underneath the grind setting bar and if your grind setting does not match the TrueGrind calculation, it will be displayed in an orange bubble with an arrow point long the direction you should adjust your grind. Go too far, and the arrow switches direction. When you reach the ideal setting, the orange bubble disappears, letting you know that your grind matches the calculation. Pretty slick.

TrueGrind Experience
I have found the grind calculations to be fairly accurate, and there is a dial-in feature that helps you hone in on the perfect setting, but there is a caveat. The grinder uses time-based grinding to reach your desired dose, which is repeatable enough, save one annoying fact of life. Grind size determines grinding rate. Unfortunately, the TrueGrind system missed a major opportunity to account for this during the dial in process. The Dial-In Assistant (available from the home screen, beneath the purge icon) asks for yield and shot time and calculates a new grind setting, but it assumes that the dose was right-on.

In an example with the C&C Congo, I had a 20g dose dialed in at 3.2s of grind time, but wanted to shorten the shot time to hit my recipe target. The new calculated grind setting probably would have worked fine, but my dose bloated to 21.3g. So now my shot time remained basically unchanged since the added dose countered the coarser grind. Trimming the grind time down to 3.0s corrected the dose and the new grind setting was basically right on, but if I hadn't weighed my dose, I would have entered into a vicious dial-in cycle where the grinder would have calculated an even more coarse grind setting.

I mention this as a missed opportunity because the grinder has everything it needs to know to recommend a new grind time simply by adding actual dose into the dial-in screen. The screen assumes that dose is correct and will be correct after adjusting the grind, and this just isn't the case. Since the timed grind setting is saved in the grinder's firmware, it would be just a quick lookup to see what the actual dose and actual time setting are to recommend a new grind time to go along with the new grind setting to keep dose constant. Maybe Clive can convince Eureka to offer this functionality in a firmware update. This addition would make the user interface really shine and make the most out of all that the TrueGrind system has to offer. The slogan of the Lucca Atom is "So long wasted beans. Hello Lucca". Right now, it is half of a fantastic solution to the dial-in process.

I'll echo the other reviewers' comments. The Lucca Atom 75 is lightning fast, repeatable, and makes good espresso with minimal effort. The workflow is hard to beat. Below is an example of a shot pulled with the grind, tamp, pull workflow.

Taste wise, the Atom Lucca 75 does not disappoint. It is armed with uncoated burrs that appear to share the same geometry of the famed Mythos. The burrs have a wide sweet spot and present the coffee in a very crowd-pleasing way. I have done several comparisons with the 98mm blind SSP High-Uniformity burrs in Ultra and the Lucca was no slouch. Shots from the Lucca are softer, more round and subtly sweeter on the front end with more body than the shots from Ultra. The trade off is in clarity and complexity, with the Ultra shots bringing out the individual fruit character and juiciness on the front end of the DRC coffee from Cat & Cloud that faded into a lasting graham cracker finish that stayed with me. The Lucca shots presented the graham cracker up front with a "mixed tropical fruit" spread, but faded quickly. As the shots cooled, the Ultra shots presented more and more sweetness to go with the juicy acidity, while the Lucca shots became more angular. Funny how things work.

I'll continue testing over the next few weeks with a few more coffees and see how things shift as I become more familiar with the Lucca. I also intend to do some puck prep studies and see if there is any measurable impact on the output when using WDT and/or downward tapping to settle the grounds vs the simple grind, tamp, pull workflow.



Thanks to Clive Coffee for providing the LUCCA Atom 75 grinder for review.
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