Thanks Ben for this very helpful discussion. You have enhanced my
understanding of espresso brewing by a great deal.
Allen
-----Original Message-----
From: Benjamin McCafferty
Sent: Thursday, March 03, 2011 12:29 PM
To: [email protected]
Subject: Re: Newbie Question #2
Hi Allen (and Pete, some more thoughts for you),
I suppose you have a point there, so I broke out the calipers and did some
measuring. I measured the difference between the bottom of the PF ears at
its thickest (fully engaged) and halfway across the ear (halfway engaged).
I don't consider less-than-halfway-engaged to be very safe, so didn't
measure that.
The casting is not precise, so the differential was anywhere from .2 mm to
.5 mm between those two points. Taking the worst case, that would mean the
puck was .5 mm closer at full lock than at half lock (6 o'clock vs. 7 o'
clock). For reference, a dime is measuring at 1.3 mm thick, so this is a
bit more than 1/3 of that thickness.
Personally, I doubt this makes a ton of difference, as long as you have a
reasonable grind/dose/tamp to begin with. That said, many of us have used
the "dime test" in the past--grind/dose/tamp as usual, then place a dime in
the center of the puck. Load the PF into the group, then carefully remove
it again. Ideally, the dime will be lightly dented into the coffee, but not
submerged below the surface, if that makes sense. So referencing the
numbers above, if the dime is barely denting vs. halfway into the puck, I
doubt you'd be able to taste a ton of difference, but probably someone on
this list could!
Allen, as an aside--I would tend to agree with you regarding pitting on a
thin puck, but I don't see a difference in coffee on the screen--I get that
no matter what. I will say for sure, however, that when I have things
dialed in well, my pucks in the knockbox are firm, somewhat pliable, and
with the dent from the screen center stud visible. They don't crumble and
they're not sloppy wet. They will frequently just stay on the knockbox
crossbar, slight bent around the bar, and not fall into the box. It's a
beautiful thing.
Pete, You can find a lot of past posts on dosing also, but there are two
basic philosophies--dosing by weight and dosing by volume. By weight gives
you precise control over how much grind you put into a puck, i.e. you
measure out 14g or 20g or whatever and then grind it into the PF, distribute
and tamp. Dosing by volume is easier, because you just grind into the PF,
use whatever distribution method suits you, then level off the basket before
tamping. Dosing by volume also accounts for the fact that different roast
levels weigh different amounts for a given volume--i.e. a dark roasted bean
is lighter in weight than a light roasted bean. So by volume you will
always have the puck be approximately the same thickness. By weight will
give you a more "known" starting point when you're trying to dial in a
specific roast or blend that you'll be using again and again. Members of
this list get amazing shots both ways; I dosed by weight for a long time
then switched to volume a couple of years ago, and have been very happy with
both--I'm just lazy and like the convenience of volume. When I really want
to work on a specific coffee, though, I use weight to really split hairs.
Regarding puck thickness, you will also see a dented line in the PF basket
(at least on the double basket), and that is a "dosing line". The puck
should ideally come to about the bottom of that line in order to have a good
dime test and a good pull. Obviously if you dose by weight you will vary
widely from that line, but not to worry--you will be using taste to guide
you, and your main adjustment will be +/- weight, with minor tweaks in
grind. Dosing by volume you will most always hit that line more or less
dead on, and then your adjustment will be the coarseness of the grind
instead.
While I strongly support your efforts to dial in the precision/science
aspects of the machine, I would also suggest that espresso is a dance. You
are dealing with at least five variables at a time, and you usually won't
have perfect control over all of them. I can think of: coffee blend, roast
level, bean age, grind, distribution, tamp, relative humidity, brew
pressure, brew temperature, water hardness, etc. etc. In the beginning, try
to use a single coffee over and over and try to only change one thing at a
time until you understand what that change means. Over time, you will find
that it will become second nature to move with the weather, the roast, the
age of the beans, etc., and you will only waste maybe a shot or two before
you hit a good combination for that day. Just avoid the temptation to start
tweaking everything at once, i.e. "that sucked, maybe I'll drop brew
temperature, grind finer, use more coffee, and tamp harder!" If it ends up
being a great shot, you have no idea what change made the difference.
One other word of caution is to ignore "absolute" advice. There are some
good guidelines out there, but they are just that--guidelines. For example,
the "golden rule" states that a good espresso pull with yield 2-2.5 ounces
of espresso in 25 seconds or so. While this works out very well sometimes,
I will also say that the very best shots I've ever produced have included
some that yielded 1.5 ounces in 40-50 seconds. Does that make the shots
bad? No. They tasted amazing, and so I did something right. The "rules"
will give you an approximate starting point, but your unique set of
variables will be different than anyone else's.
A few things that made immediate, dramatic improvements in my shots:
--Get a tamper made, that fits your PF basket precisely. This will more or
less eliminate side channeling (and don't try to polish with the Thor, it
will wreck your puck). http://www.thortamper.com/
--Use the Weiss Distribution Technique. I use a stainless canning funnel
(ebay) instead of the yogurt container. I cannot stress enough how dramatic
of an improvement this was. My "needle" is an easter egg dipper with the
small end cut off, or an unfolded paper clip in a pinch. :)
http://www.home-barista.com/weiss-distribution-technique.html
--Home roasting (I use 70% decaf and it is cost-prohibitive to get this
fresh enough for decent shots in pre-roasted form--4 days old or less).
--Lower brew pressure--9 bar or so with a blind PF, 8.5 bar or so during
brewing. I have found higher pressures (12 bar) to be too high and hard to
overcome channeling.
Everything else has seemed to be variable, based on coffee type, roast
level, etc.
Anyway, not sure how I got off on this (very long) tangent, but I guess it's
a metaphor for the whole process. :) Enjoy the new machine and hit us with
questions anytime. Hope you're getting some good shots already! I am
eagerly awaiting my PID and rotary pump conversion kits, which will arrive
next week.
best,
Ben McC
Seattle, WA
On Mar 3, 2011, at 11:26 AM, Allen Worrall wrote:
Ben, does the position of the handle have any influence on the distance
between the screen and the packed coffee? And if so, does this have any
significance? I have the impression that if I let the space between the
screen and the coffee become too large, (by not using enough coffee
volume, which in turn is affected by the grind) after the pour the surface
of the coffee puck is eroded and pitted, and there is lots of coffee on
the screen.
Allen, in Fairbanks, Alaska (But in May moving to Lakewood, WA, near
Tacoma and Seattle, so maybe we will meet someday at an espresso
conference).
-----Original Message----- From: bmacpiper
Sent: Thursday, March 03, 2011 7:46 AM
To: Brewtus
Subject: Re: Newbie Question #2
Hey Pete,
If your machine arrived really cold, the gasket is just hard and will
soften at room temp and/or operating temp. Also, the gasket comes in
various thicknesses, so you can always get a thinner one if you really
need to. I use a Rancilio bottomless PF, and the 8.5mm thickness
gasket works fine for that and the original Brewtus PF. Here is a
place to get gaskets (good to replace once or twice a year anyway):
http://www.chriscoffee.com/products/home/isomacparts/e61groupgasket
You would order one of the first three in the drop-down list. I
believe the original on the B2 was 9mm, because when I got the
Rancilio, I could barely lock it into the group, and had to get a
thinner one. As an aside, there is no "correct" position for your PF--
the basket is round, so it makes absolutely no difference where the
handle is in that respect. Your primary concern is that the PF gets
locked in securely, so that it doesn't come loose under pressure and
shower you with near-boiling water/coffee. I have used machines that
barely got to the 7 o'clock position, and were totally fine, but
obviously getting towards 6 o'clock gives you better/full engagement
of the ears on the PF into the group. Just don't yard on the PF
handle--it is unnecessary. A good firm twist is plenty--if you're
moving the machine, you're pulling too hard.
Since we're talking about changing gaskets, I'll mention to you that
changing your group screen once or twice a year is another easy and
cheap way of keeping your shots top notch. This is a part that can't
be cleaned effectively, and over time builds up crud. Search my
previous post on this, and there are pictures in the gallery of a
screen that I tore apart after significant cleaning, i.e. more than an
hour soaking in Cafiza. The pictures speak for themselves. (The post
is here, fourth one down with my name on it:
http://groups.google.com/group/brewtus/browse_thread/thread/d1731f9f2ad64ac0/4989e48d94e67cdd?lnk=gst&q=bmacpiper+screen#4989e48d94e67cdd
)
Screens here, use the first one in the drop-down list:
http://www.chriscoffee.com/products/home/isomacparts/faemae61groupscreen
best,
Ben McCafferty
Seattle, WA
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