hello kitt,
here my reply to the first of your mails, the other will follow later.
Pressure against a blank,
i've tried different settings, haven't settled definite yet, it was just
a notch above 9, say 9.2. i have set it to 9.5 now, but this might be
too high, i'm not sure here. the previous setting ramped up to 9 bar
(with coffee) and the dropped to 8.5 as soon as the espresso has started
to flow properly.
in the beginning, it was set much higher. that was not good. i've gone a
bit lower than i am at now, but that did not help. i've been testing as
low as 8 bar with coffee, measured after the drop following the ramp up.
i don't think i should go lower, unless the gauge is giving faulty
readings. i suppose that's not very likely the case.
Temperature after a four oz flush and five second pause,
i can't measure with a styrofoam cup, i don't have one but will try to
find it. for the display reading, it does not seem to matter much
whether 4oz is pulled or not. it just behaves the same as when i hadn't
pulled the shot, this time it stayed where it was, at 94.
what i should mention, however, is that the 'heating request' dot is
always flashing, idle or not, in an interval of estimated about 1.5
seconds. it takes all too often (but certainly not always) more than a
minute to get back to normal after an 1 degree celsius drop, even if the
steam boiler is not requesting heat.
these drop occur rather often. i would estimate that the display shows
the requested temperature value for about 3/5 of the time, 2/5 of the
time it is lower than it should be. it seems to be always requesting heat.
is all this normal?
and what do you make of the steam boiler pressure, it gets never above 1
bar. when it heats up it stops around 0.95 bar. i read that i should be
1.2 bar. it has never been 1.2 bar. could this bear a relation to the
difficulty to get to the right temperature of the brew boiler, as these
two are linked? or in any other way contribute to the problems i'm
having? that's just a thought that has occurred to me.
is there a way to adjust the steam boiler pressure?
Shot pour time,
variable, haven't set for anything yet, see my mail from yesterday about
the very long pre-infusion time vs flow rate. what do you think of this
theory?
when i started, i aimed for about 27 seconds. i've experimented with
longer times, up to 35 seconds. i'm still on the fence on what works
best. when i'm not experimenting, i still aim for 27 seconds.
Basket used.
both the standard brewtus basket and one that's exactly the same
(shape,hole density/size), but slightly smaller. with the standard
basket, i think the amount of coffee that worked best was around 15 or
16 grams, not entirely sure (my memory fails me) and the smaller one
just a little over 14 grams (this does depend on the coffee, and the
roast type in particular.)
same faults with either basket.
Presence of channeling
when i started with this machine, a LOT. really, just an awful lot. i
have worked and worked to reduce this. got a new tamper, started to do
the wdt, methodically tuned the fineness of the grind vs the amount of
coffee.
i have been able to reduce it a great deal, but not completely.
i have to admit, the problem i have do taste similar to over-extraction
or channeling. but i wouldn't know what to do about it anymore than i
already did. i've read all i could find on the subject of channeling,
tried every suggestion i could find.
if there's still channeling going on, and this is the cause of my
problems, i wonder what is causing this problem. i don't think this
would be normal.
BTW ... Have you confirmed that the water from each boiler is untainted. I had
that problem once.
i have tasted the water. before, it tasted fine. in time, it has gotten
some *very* subtle tarry accents. i have cleaned the grouphead (taken
the shower screen off.) i clean the showerscreen and it's sides after
every shot. i do backflushes regularly, once in a while with a cleaner
made for this purpose.
I will confess that I am extremely uncomfortable with three of your data
reports:
Baskets
Channeling
Verification of data accuracy
what did you mean with the third part, 'verification of data accuracy'?
First, the change in baskets makes me uncomfortable. There is
nothingsacred about the Expobar filter basket, but using something "smaller"
is a little unnerving.
why is that?
the problem is exactly the same with the bigger basket in any case. no
difference at all.
I use all Gaggia baskets because I dose directly into the filter
basket and tamp before inserting into the portafilter. I do not want the
snap of the Expobar basket passing by the retainer ring. That is just my
particular choice, it gives me more confidence that one more variable is
probably consistent from shot to shot.
i dose directly into the baskets, too, leave the portafilter into the
machine. i have removed the retainer ring to avoid the snapping. this
couldn't be causing any trouble, could it? (i have to look at every
possibility now, every little detail)
How do you determine the weight of your quantity of coffee in the basket?
> ( I weigh every dose.)
just the basket on my scale (a very accurate one) zero it and then
weight the full basket. i always work with the exact same amount for the
same batch of coffee, unless i'm trying something out of course.
What is the color of the shot ... Is it the same for both the Gaggia and the
Expobar?
yes, getting the right shot color is easy. but sometimes with the
brewtus, i see a drop of that all-too-blonde crema in the further fine
colored cup. i assume this is a sign that channeling has occured. i
never noticed that with the gaggia, by the way, and it's not always
there with the brewtus.
Have you measured the water temperature of the pour ... Do you have a Scace ?
do you use the Styrofoam cup technique?
i have neither, but i will find a styrofoam cup sooner or later. there
aren't very commonly used where i live, haven't found a place to buy
them unless i get thousand pieces.
The fact that you can not reproduce the results of your Gaggia unit,
even though you are using the same roast, the same filter basket, the
same tamp, and have no channeling is disturbing.
i agree. very disturbing. it took me a little while to really admit it
to myself that the gaggia works much better than the brewtus, even after
all the effort i have been putting in. months of work, and the first
shots i made on the gaggia were already better than anything on the
brewtus so far.
that's why i called for help. this needs to be resolved, it just can't be.
i want to thank you again for caring. i appreciate it a lot.
all the best,
guido.
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