LaCimbali Junior DT1
Espresso Performance


Illy Schwung cup An earlier how-to, How I Stopped Worrying and Learned to Love HXs, focused on managing the brew temperature of prosumer E61 espresso machines like the Andreja Premium by Quick Mill. However keep in mind that most of its observations and suggestions apply only to E61 prosumer machines, not the Cimbali Junior, whose temperature management is considerably less complicated. In fact, I consider Junior an exceedingly civilized heat exchanger espresso machine. Temperature stability is one of Junior's claims to fame and months of use confirmed this to me, although it requires a few extra steps to initially "tame" Junior to a predictable curve after a long idle period. Like all commercial machines, Junior shows its stuff best when run continuously and run hard. If the Cimbali has any weakness in terms of temperature management, it would be when it's used intermittently.

This should come as no surprise for a commercial machine, which generally have heavy groups that need a few flushes and several shots to reach their ideal brew temperature. But for practical reasons, a home barista preparing only an espresso or two will want to get to the same point temperature and stability-wise as they would see on the fifth and sixth shot, but as the first and second. I had the Andreja Premium in-house while researching this article and recognized immediately that the flushing regime for an E61 was quite different than Junior's. The Cimbali Junior still needs to be flushed, but not nearly the same volume as a prosumer E61.

One reason for this difference is the size of their respective heat exchangers. Junior's heat exchanger is much larger and a smaller percentage of its total volume is submerged in the boiler water compared to Andreja's. The deeper a heat exchanger is submerged in the boiler water, the faster the heat exchanger's temperature will rise since water conducts heat much more quickly than steam. If you don't remember your high school physics, think of it this way—you'll sweat profusely in a sauna heated to 140°F, but the consequences of immersing yourself in water at that same temperature for even ten seconds would be gravely serious.

To get a quick feel for the performance characteristics of a new machine, I do a temperature profile test nicknamed "drop off." It involves pulling a shot and continuing to run the pump until the grouphead water temperature falls off, providing a general idea of the HX size and temperature stability without the need to disassemble the machine. In Junior's case, the results were incredible: After the temperature leveled around 12 seconds into the shot, it varied little more than 0.5 degree for another forty-five seconds (the pump auto-shutoff stopped the test at one minute). No prosumer HX machine that I've tested is capable of such lengthy tail-end stability.

How I Learned to Love HXs (Summary)

Managing the cooling flush regime, compared to prosumer heat changer machines, is a snap with Junior. The flush is short and sweet, and with the exception of the first warm-up of the day, only modestly affected by how long the machine has been idle. In that regard, getting fifth shot quality from the first shot of the day on a commercial espresso machine is analogous to parallel-parking an RV: It can be done, but requires extra maneuvers.

The general rules of thumb for Junior are below, including the exceptions necessary to wake Junior from a long slumber for the first espresso of the day:

  • Program the dosing keys (Spritz, Mini Flush, Double, Big Flush).

    See the steps described in Programming the Volumetric Doser Buttons for instructions.

  • If idle for more than five minutes, press Big Flush.

    If it's the very first time of the day (really, really idle), this flush raises the group to temperature, but a few extra flushes help get the big hunk of metal components called the brew group all singing to the same tune. To simulate the heating that naturally occurs over the course of the first half-dozen shots, follow Big Flush with Double three minutes later, and then three Mini Flushes at one minute intervals.

    It's a few extra steps that really improves the first shot of the day. To summarize the early-morning startup routine: Big Flush, pause three minutes, Double (flush), pause one minute, Mini Flush, pause one minute, Mini Flush, pause one minute, Mini Flush, pull your shot. Precisely following the suggested pause times to the second are not critically important and I integrated this into my normal preparation routine of gathering cups, cleaning out the grinder, measuring beans, and so on.

  • If idle for about three minutes, use Mini Flush. If unsure, use Spritz and observe the flow of water; if there's steam, press Spritz again.

Keep in mind that the above suggestions are for those who really, really want to squeak the best shot from Junior straight out of the gate. If you're a "keep it simple" sort of person, the abbreviated routine after five or more minutes of idle time is just one step: Press Big Flush. There's no need to wait more than few seconds for the temperature to rebound before beginning the extraction. After the flush, lock in and press Double for a metered shot, or the Free Pour button to start the pump and a second time to stop.

If you forget to flush over-temperature water from the heat exchanger, the first two-thirds of the shot could be scorching hot, depending on how much you've flushed through the group earlier. Even so, it's worth noting that the same omission on a prosumer E61 will assure blistering-hot boiling water through the entire shot. One of Chris' repair technicians who frequently works on Cimbalis commented that E61s run hot. After you've pulled a half-dozen shots on Junior, the basis of his observation is pretty obvious.

Pulling Shots by the Numbers

Tiger striping The bottomless portafilter highlighted in Perfecting the Naked Extraction dramatically shows the beauty of the extraction process; it reminds me of melted milk chocolate flowing into the cup. The contrasting colors, called tiger striping are excellent visual cues of a good extraction. Once settled in your cup, they form darker brown speckling and reddish-brown splotches on the surface of the crema referred to as mottling.

Below are the steps for pulling your first shots. Because managing the brew temperature is very easy on the Cimbali Junior, your attention can focus on the quality of the extraction. Let's assume that you've adjusted your grinder for a reasonable 25-27 second extraction:

  • Allow Junior at least 90 minutes to warm up.

    An accurate and stable brew temperature relies on the entire brew pathway being up to temperature. If you prefer not to leave Junior on 24/7 and you're rushed in the morning, consider a timer to preheat the machine before you wake (I recommend the heavy-duty programmable Intermatic digital timer model DT17C, available at Home Depot for less than $25).

  • Grind and dose your coffee beans. Remove the portafilter, fill and tamp firmly with about 30 pounds of pressure.

    Generally I measure by volume, but some use a precision scale to weigh out the beans and run the grinder until empty. I found that 15 grams of coffee beans / a small heaping basket full of grinds worked great (a level basket holds around 14 grams before any settling). Smooth out the grinds to an even bed of coffee as described in Dose, Distribute, Tamp. Repeat.

    It is important to have some clearance between the dispersion screen and the top of the puck. This facilitates the even distribution of water over the surface and for the puck to expand upward to meet the dispersion screen as it absorbs water. At the maximum dose, the screw holding the dispersion screen will lightly graze the top of the puck when the portafilter is tightened down, but be aware that if the puck is grated on lock in, side channeling is probable. The optimal weight will vary for the grind setting, beans, and type of grinder. I found for our house favorite, Intelligentsia's Black Cat, the right dose was right around 15 to 15.5 grams; it becomes difficult to lock in the portafilter with around 16 grams of coffee.

    Once tamped down, the coffee will leave the top of the ridge for the basket retention clip exposed. Junior's portafilter is heavy and the bottom of the bowl is made of thick brass. After the first "wake up" flushes have been done through the portafilter, it's at temperature and the Mini Flush can be done with the portafilter out of the group just before locking in. This is more practical than trying to flush, dose, tamp and return the portafilter to the grouphead in the mere 10-15 seconds after the cooling flush before the water reaches your target brewing temperature. Alternatively, if you prefer to keep the portafilter in the group for the maximum time, try removing the retention clip from the portafilter so the basket drops in and removes easily. Then you can tamp at your leisure while the portafilter remains in the grouphead. Once the basket and coffee are ready, a quick turn to remove the portafilter,flush, drop in the basket, then back in the grouphead.

  • Draw water through the group with the portafilter removed.

    Junior's recovery time after the cooling flush is too short for all but Speedy Gonzales. I certainly can't dose, distribute, and tamp all before the water in the heat exchanger goes well over the target temperature.

    I found it easiest to remove the portafilter, prepare the basket, and then do the cooling flush by listening for the hissing of steam and boiling water before locking in. Continue drawing about a half-ounce of water after the stream has settled down (total flush time less than 10 seconds), around 1½ ounces total, especially if you've recently pulled a shot. Depending on the blend and your taste preference, the recovery time after the cooling flush is somewhere between 10 seconds (puck surface temperature briefly peaks about three or four degrees Fahrenheit above target brew temperature) to 30 seconds (puck surface temperature briefly peaks around six degrees above brew temperature).

  • Lock in the portafilter and press the Double button to start the extraction.

    Take a moment after you're done pulling shots to rinse the grouphead by loosely locking in your second portafilter with the backflush disk and running the pump while slowly jiggling the portafilter handle back and forth. This "wiggle-rinse" will wash most of the loose grinds off the grouphead and dispersion screen and over the sides of the portafilter into the drip tray. Be careful not to splash yourself and watch for hot water running down the portafilter handle! Place a bar towel over the front edge of the driptray to catch errant droplets of water.

Remember to relock the portafilter back into the grouphead to keep it warm.

At the end of a session, I also recommend a quick water backflush to clear the pathway from the grouphead to the pressure relief valve that empties into the back of the drip tray. Refer to Espresso Machine Cleaning - Why, How, and When for more details on a cleaning regime that broadly applies to the Cimbali Junior.

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