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LR observations after adjusting PI pressure
I was surprised after making a change to lower the preinfusion pressure (1.5 turns clockwise from factory setting) that beading began earlier than at higher preinfusion pressure. I was expecting the opposite. With no change to blend or grind setting lower pressure should require more time to fill the chamber and saturate the puck.
Tastewise the espresso is less bitter (it's a darker roast) so I'm confident that CEME is not reversed if that is even possible.
Has anyone else had a similar experience? Why does this happen?
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Tastewise the espresso is less bitter (it's a darker roast) so I'm confident that CEME is not reversed if that is even possible.
Has anyone else had a similar experience? Why does this happen?
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Comments
thank you for your post
what grinder are you using?
are you stirring the grounds before tamping?
kind regards
reiss/
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a very nice grinder by all accounts!
it is clear from your report that the brew temperature has been reduced that the pressure switch is doing its job
i expect the first drip issue is one of distribution - i understand that denis suppliers his grinders with a stirrer - if so i would definitely recommend that you use it to improve consistency
the only thing i can think of that would cause what you are seeing is older/less fresh beans or a machine that has not been allowed to fully warm up; a reduction in the pre-infusion pressure will mean that the machine takes longer to get up to operating temperature from a cold start. put it on a digital timer if you haven't already and have it turn on at least one hour before you need it and ideally 90 minutes
if the brew temperature is too low it is going to race through the beans
i am also surprised that you have had to turn it back a turn and a half - that is more than i have ever gone; is the lever grabbing above 45 degrees now? if so i think you should increase the PI a little - perhaps back up half a turn
let us know
reiss.
The machine is on a timer and had been warmed for about 70 minutes this morning.
I will shoot a video tonight to show the distribution.
Regarding lever catch. At this PI setting it catches a few degrees above the bottom position (<45°) after only 3 seconds!<br />
Somewhere I read one full turn equals 1 bar. Frans' HB post I think.
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The 1.5 turns CW seems to be a great spot for this blend.
http://www.socialcoffee.com/products/people-s-daily-espresso
I will eventually try shots at incrementally higher PI to see what I can learn and report back.
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Frans does indeed say, in his LR has arrived thread that 'One full 360º turn is little more than 1bar difference.'
He also says that his LR arrived with the pre-infusion set at 2bar.
I would be most surprised if Frans did not measure these values?
Reiss however states that the factory setting for pre-infusion is set at 3bar and given that the Ceme stat has a working range 0.2 - 6 bar it would make perfect sense, to me, for the units to ship at that mid range value.
Reiss also comments on how the LR pre-infusion pressure can be adjusted by reference to simple analogue measurements, like -1/2 turn, rather than any pressing need to measure actual pressure. As someone who has neither the equipment nor the inclination to determine actual values, I'm more than happy with that.
However, my question is.... how consistent is the factory setting? Is my factory -1/2 turn the same as Frans'and Michael's* ?
Ultimately, if we all adjust and use taste to home in on a correct setting then it doesn't matter but if, like me you value the guidance of the great and the good such as Frans and Reiss then it is preferable that there is a common point of reference.
1.5 does seem a lot.*
Having heeded Reiss' advice I have dropped my boiler pressure down to 1.0bar.
On my current dark end of medium roast beans I initially backed off -1/2 turn from factory pi but have since revised to only -1/4, with favourable results.
I am keeping a note of where I am relative to my factory setting.
If needed I can measure again to see what one full turn does, but in my view it's best to taste the coffee, sensing the difference between a very early 'catch' just above horizontal and one that 'catches' halfway up for instance.
If you come from an old model L1, you might want to grind a little finer against the higher pre-infusion and there as well you can check out and taste the difference between a nice full creamy mouthfeel and sweet taste (assuming you have fantastic beans) and, if you raise p-i pressure still more and/or grind ever finer, the point where it becomes overwhelming, overdoing it, slamming the taste.
Mine was one of the very first machines and after that first production week, if I understand it correctly I believe the boilers on new production slots were set to 1 bar and the pre-infusion on 3 bar.
this will explain why your machine arrived with a boiler set to 1.3 and why turning the Ceme pressure switch down by half a turn may have been too much (i expect it was set lower than 3 bar to start with)
the Ceme will respond similarly to an adjustment of the same amount, for example, a half turn
i am arranging for portafilters with pressure gauges to be made but i dont want them to have the useless 40mm gauges - something like 60-65mm diameter is necessary to be able to accurately read what the pressure is, as the gauge really needs to have a 0-10 bar range unfortunately. since we are going to the trouble I'm also going to fit wenge handles to them so you dont have a kitchen full of mix & match items
kind regards
reiss.
In order to see what is happening with pressures I’ve mounted a pressure gauge in the port on the back of the group. This gives a record of the pressures up until the lever is released.
The plug is 18 x 1.5MM. I found a tapered blind plug that I taped to take a 1/8 inch BSP nipple.
I’ll probably connect a strain gauge and publish the pressures when time allows along with the complete story of my modifications.
Nice! Maybe there are gauges available that also show the temperature??
Lever catch point at my factory setting would appear to back that up.
Just tried a lighter roast at my factory + 1/2 a turn pi.
Lever catching only a few degrees above horizontal and a very nice extraction.
Also, wouldn't the gauge measure pressure up to the point where the lever catches, rather than when it is released? Although, I guess on a modified old L1 or an LR that would be close to the same point.
Matt
The same group is also used as a dipper group, which is a little bit different at the neck. Then it is possible to put a closing mechanism into this port so that on a multiple group machine just one can be closed and maintained while the other groups can still be used.
Mark
hi matthew
when the group is used in dipper configuration a non return valve can be fitted in the neck of the group
as mark has said bosco fit a valve that can be used to adjust the rate of flow through the group. for servicing this valve can be turned right down to the extent that it closes
kind regards
reiss.
Matt
I aim my roast to be consistently of about the same roast intensity, measured in a roast color acquired over a certain time. Mostly color Tonino #95 with a 15 minute roast.
With a new bean it takes some time to tweak the roast profile and with a Sumatra bean I roasted the first batch rather dark, Tonino #83 even. That's not exceptionally dark compared to many beans sold in shops, they are not oily for instance beyond a tiny spot here and there on a few beans. But these Indonesian semi-washed beans which tend to have lots of 'body' already behave like dark beans, with a faster flow.
Before, I would send these to a friend that I know who finds that really dark beans work best in her automatic coffee machine.
Now I tried them myself and I find it yields delicious spicy earthy coffee with lots of body even when using just the 15g VST basket instead of the 18g basket I mostly take.
This works so well thanks to the variable pre-infusion pressure.
I took off the lid of the L-R an turned the adjustment on the Ceme p-stat so that the pressure is very low but pulling the lever stil activates the pump.
Result: a subtle delightful Sumatra in the cup with lots of body while not bringing too much of it.
Works fantastic as a cappuccino as well. I practically never froth milk but it was yummy.
Same Sumatra Mandheling, now using the original Londinium cup. Like yesterday, the 15g VST basket instead of the usual 18g VST, lower pre-infusion pressure and thus lower extraction pressure / temperature, a faster flow and a delicious treat in the cup.
If not, when might such a beast be available. I am starting to think that it could be useful to get a read of some values and 'calibrate' the Ceme adjustment screw.
In practice I find it much more direct to use my taste and the observation where the lever 'catches' to decide if I want to try a higher or lower pre-infusion pressure.
That way I have a very direct visual and taste gauge.
Using the portafilter with pressure gauge, I must take care to release air and try to make it likely that it's the same amount because that also influences the reading. So it's a reading that is rarely perfectly exact and at best very usefully indicative, but the angle of 'lever catch' is more directly indicative of the pressure and the tamp, grinds etc.
When the spiffy good looking Londinium gauge comes out, I might still get one though as I trust it will be good value for money and an instrument that is not run-of-the-mill, few will have one and they will stay rare, I expect.
But if you assume you *need* one, think again ;-)
hi tony
yes, i haven't forgotten. the factory has been pretty busy to date this year - hopefully things will ease off as the northern hemisphere summer arrives and it will be a nice little project we can slide into production at that point
best
reiss.
More born out of curiosity Frans than thinking I have a desperate *need* for one.
I'm currently keeping a note of how many quarter turns I am away from my initial setting. If it produces the goods then it matters not what the actual pressure is nor how much difference a quarter turn makes but there is a small part of me that is curious.
Let's wait and see if I'm still curious as and when the Londinium gauge becomes available.