Help with La Cimbali Jr.

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SamuraiE

#1: Post by SamuraiE »

Dan, you out there? I have been using my Jr. for about 2 weeks now and have become more familiar with his ups and downs. I have read your article from the Chris Coffee link several times, even though it is a direct pumbed in machine and mine is not (pourover). Questions:

(1) Seems like the boiler pressure was set by the factory at a peek of 1.1 on the gauge on the front of the machine, at least that is the highest it has ever gone....the cooling flushes needed are quite long indeed. I often must draw a full cappa cup worth of water before pulling a shot just to get a nice smooth stream of water coming out of the pf at the end of the flush and this is not after a long idle rest period. This seems to drop the pressure down to 0.8 or so, should I go ahead and pull the shot now at 0.8, or wait for the unit to go back up to 1.0 or 1.1? If I wait it seems to be too hot again.

(2) A friend has told me he played around and adjusted his brew pressure(?) saying brew pressure is different than boiler pressure. Am I correct in thinking that boiler pressure is responsible for the temperature of the water coming out of the machine? What is brew pressure and where can I adjust it on this machine? Is an adjustment needed? Any advice on this subject would be most helpful.

shots are good but should be much better.....grind and tamp are good....extraction time is dead on.....shots taste sour, bitter (honestly can't tell the difference between the two). Crema is good, especially on the Monkey blend which arrived yesterday from SM. I did pull one shot at 0.9 using the Monkey and it was out of this world, but have had trouble matching it.

thank you
I am not worthy!

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HB
Admin

#2: Post by HB »

DISCLAIMER: UNPLUG THE MACHINE BEFORE MAKING ANY ADJUSTMENTS. ELECTROCUTION IS DETRIMENTAL TO YOUR HEALTH.

I tried boiler pressure settings from 0.7 to 1.3 bar and settled on the original factory setting, which was 0.9 bar in my case (measured from the top of the cycle). You can change the boiler pressure and thus the temperature by turning the 7mm nut atop the pressurestat spring (tighter = hotter):

Image

The brew pressure is indeed completely different than the boiler pressure. Since Junior has no brew pressure gauge, you must use a portafilter pressure gauge, similar to the one below:

Image

A brew pressure of 8.5 bar is a good starting point. Your model (S1) has a vibration pump and presumably uses an expansion valve to regulate the maximum pressure. Jim Schulman explained the mechanics of vibe pump pressure regulation that apply to your machine. I'll defer to Chris' technicians for the specifics, since I had the DT1 (rotary) model and thus don't have any pictures.

Begin by lowering your pressurestat setting and then look to the brew pressure. Once you have the pressurestat setting correct, you can pretty much ignore the boiler pressure gauge. Junior's heat exchanger and boiler are large enough that the position of the needle at any given time is inconsequential for the purposes of pulling shots. The flushing regime I detailed in the guide should get you started, then you can fine-tune it to your tastes and blend selections.
Dan Kehn

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SamuraiE (original poster)

#3: Post by SamuraiE (original poster) »

Thank you Dan. I'll send for the gauge and see where it takes me. Will also continue to read through this fine site. Again, thank you for getting back to me so quickly.

Key
I am not worthy!

bobroseman

#4: Post by bobroseman » replying to SamuraiE »

Key,

It seems to me that if your going to measure brew pressure and make adjustments, then you need to know the exact pressure that you have while pulling a shot. Most portafilter gauges measure only the static pressure at the brew head when the by-pass valve has opened. That is not the pressure you are getting when you are brewing espresso. The attached photo is a simple mod I made to the gauge I bought from Chris Coffee. I can adjust the needle valve to allow precisly 2 oz of water to flow in 25 seconds while reading the pressure. On my machine, the resulting pressure is 8 bar, as seen in the inset.

Bob
Image

here it is in use:

Image

cinergi

#5: Post by cinergi »

Bob,

what hardware store did you get all those fittings from? They even had the needle valve?

Thanks.

bobroseman

#6: Post by bobroseman » replying to cinergi »

Hi,

I brought my portafilter to Home Depot and picked up all of the parts, loose fitting them on the spot.
The only thing I brought in was the pressure gauge. Don't forget the teflon tape. :lol:

Bob

cinergi

#7: Post by cinergi »

Bob,

Do you know if this mod will work with Greg Scace's new thermofilter?

Thanks.

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Sponsored by Flair Espresso
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barry

#8: Post by barry » replying to cinergi »




you won't need the needle valve.... and several other connectors.

cinergi

#9: Post by cinergi »

Won't I need the needle valve if I want to control flow? And if so, I would assume I would need to remove the filter.

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barry

#10: Post by barry »

the terminal cap has a restricting orifice in it.

if you remove the filter, your needle valve will likely plug up at some point.