Dialing in a new espresso machine, a step by step guide - Page 2

Beginner and pro baristas share tips and tricks for making espresso.
User avatar
cafeIKE
Supporter ❤

#11: Post by cafeIKE »

cannonfodder wrote:The scale is a single gram so the error margin is high and not ideal for exact measurements, but for the purpose of this dialing in process, it is adequate. Regardless of whether the scale displays 17 grams but actually contains 19.5 grams of coffee, as long as it consistently reads 17 grams we are OK. The point is not to precisely measure the dose, but to provide a reference point.
Agreed the idea of a consistent reference is fine, but consistency is rarely attained. I have a couple of 5kg scales and a 100g reference weight to calibrate my 0.1g 200g scale. When set upon the 0.1g scale it has always measured 100.0 or 100.1. On the 1g scales it varies from 98 to 102 on one and 99 to 101 on the other.

Scales are more accurate near the mid point of their range. Typical range for 1g scales is 5kilos. Accuracy at sub 20g is marginal at best.

It's possible for a 1g scale to read 17 for 16.5 to 17.5 and 18 for 17.5 to 18.5, ignoring count and accuracy errors. Ergo, both a 17g and an 18g reading could actually both be 17.5 misleading the user to think they made a change when in fact they did not.

The sticking point is that some will use the posted numbers with a more / less accurate scale as a reference and be no farther ahead in getting a consistent / optimum dose.

If we are going to use numbers, we should be accurate.
If we are going to use a scale, it should be as well.

IMO, the time spent futzing with a scale is better spent learning how to adjust the dose manually by tapping the PF and how it affects the tamp and shot. Once Joe newbie has a handle on that, he's well on his way to mastering the Mano M.

If Joe newbie wants to use a scale, then get an accurate one and burn through several kilos of supermarket coffee until he can dose to ±0.25g repeatedly.


Still a great piece on getting started.
Thanks for the write up.

User avatar
cannonfodder (original poster)
Team HB

#12: Post by cannonfodder (original poster) »

Point well taken. I normally use this scale (5 pound max) to weigh out greens for roasting by the pound and ounce so super accurate measurements have not been a big issue for me. As you stated, learning to work without the safety net of a scale is not that difficult. After a few weeks even Joe newbie will grow past the scales usefulness.
cafeIKE wrote:
Still a great piece on getting started.
Thanks for the write up.
Thank You

The next installment goes up tonight.
Dave Stephens

Dogshot

#13: Post by Dogshot »

Wow! Congrats on the new machine - what a beauty. This thread is a great way to introduce us to the A3 in a different way, so thanks.

Re: digital scale accuracy. I dose by weight, and my technique is similar to Cannonfodder's; I add beans to 17gm, then add 4 more. I have found a level of intershot reliability doing this method that is inconsistent with the following statement about 1gm digital scale accuracy:
cafeIKE wrote:Digital scales have an accuracy tolerance and a count error. A scale that indicates single grams probably has at best 1 gram accuracy and a 1 count error. This gives ±1g plus ±1 count for a total error range of 4 which is far too much for a ~18g total : ~20%.
Luckily, this hypothesis is fairly easily tested. I turned on and tared my scale and added beans until the scale just tipped 17gm. Then I put those beans in another container, and re-did the same thing 5 times. Every measure was exactly the same, except for 1, which required a single extra bean to tip 17gm. I stopped testing at that point, because such low variability after 6 tries, and the level of consistency I had been getting from my shots using this method were enough to convince me that my 1gm scale achieves much better than 20% consistency between measures. Any idea why this test would not agree with the above quoted, well-informed statement? (other than that my scale is a wunder-kind?)

Mark

User avatar
dsc

#14: Post by dsc »

Hi cannonfodder

Excellent idea for a thread!! I'm a newbie and your posts gave me a lot of information on changing the variables to make good espresso. I just bought a few days old coffee, so I might just try out your advice, use a scale and see how it goes.

Cheers,
dsc.

User avatar
cafeIKE
Supporter ❤

#15: Post by cafeIKE »

Dogshot wrote:Luckily, this hypothesis is fairly easily tested. I turned on and tared my scale and added beans until the scale just tipped 17gm. Then I put those beans in another container, and re-did the same thing 5 times. Every measure was exactly the same, except for 1, which required a single extra bean to tip 17gm. I stopped testing at that point, because such low variability after 6 tries, and the level of consistency I had been getting from my shots using this method were enough to convince me that my 1gm scale achieves much better than 20% consistency between measures. Any idea why this test would not agree with the above quoted, well-informed statement? (other than that my scale is a wunder-kind?)

Mark
One minor flaw in your method is you used different beans on each test. To test the accuracy of the scale the same beans should be loaded for each test. The variablility of beans probably guarantees on some tests your count would vary ±1 bean.

There are also a time constant and acceleration effects. When I weigh 225g for roasting, if I just dribble the beans in until 225g is displayed, the value will probably hold. If I remove a few beans until it reads 224, I may have to add fewer or more beans to return to 225. If I take the same beans and dump them in as a lot, the reading will probably hold on 226. In practise, I aim for ±2, but am certainly not going to pick out a few beans if the load is 228 :lol:

Of course, this is way OTT in terms of any affect on the shot or roast, but if one seeks to mitigate variables by mechanical means, the minimum possible error should be obtained.

Over the short term, a scale left on, not subject to larger loads and loaded a bean at a time will be fairly consistent. Over the longer term with time, temperature, pressure and battery voltage variations, the repeatability will diminish.

If a scale were at all required to make great espresso, I'd switch to TEA!!! :cry:

One danger of fixating on a numerical value for a dose is that it is of limited utility for a very narrow range of criteria : ONE blend at ONE roast at ONE grind on ONE day. The barista is better served learning the range of adjustment that can be effected by adjusting dose and grind and knowing when and how to adjust them in concert.

Who knows how many newbies tear the top of the puck negating all grind and tamp adjustments, forever running in an endless loop changing grind and tamp.

Perhaps the best advice for anyone with a new machine and / or grinder is to plan on binning 2 kilos of FRESH coffee over the weekend to dial in the machine(s). If they've never made espresso before, plan on the same routine for a month. It's important to have a quantity of the SAME coffee. It's crazy to sink a grand or two into hardware and worry about a few bucks worth of coffee.

Don't even pull a shot until you can dose the PF with consistent clearance to the shower screen. Once you can do that repeatedly, pull a shot and see what it looks like. If it's in the 25~30sec range, give it a taste. If not, keep adjusting grind until it is. Then experiment by backing the grind off a notch and updosing by tapping the PF on the counter. Then go the other way and tighten up the grind until the machine chokes. Can you tamp lighter, still clear the shower screen and pull a shot? If not then that's the end stop of grind for that coffee.

Something that is seldom discussed is grinder detritus. ALL grinders retain a varying amount. If you grind a dose, pull a shot, come back in 15 minutes and grind another dose, you have a load of stale coffee in the bottom of the PF. Either grind per shot and clear the grinder by what ever means before the next dose or grind for a couple of seconds to clear the grinder.

User avatar
cannonfodder (original poster)
Team HB

#16: Post by cannonfodder (original poster) »

From the previous update we learned that an 18 gram dose with fresh beans does produce a better shot but does not resolve our slow center extraction and end of shot channeling. Looking at our previous tests we see that a reduction in the dose had a marked improvement in the extraction. So the next logical step would be to further reduce the dose and see what happens.

As I stated at the beginning of the post, grind/dose and tamp are all part of the same formula. So when we desire a different result, we must change the equation. When we change one variable we often have to compensate in another. When we reduce our dose we have to fine up the grind to compensate for the thinner puck. So keeping that in mind, I drop to a 15 gram dose and drop the grinder from 4.5 to 4.0 and retain the same tamp.
«missing video»

Isn't that interesting. We are getting a more even extraction in the start, the coffee flow starts relatively even across the surface of the basket. The flow was too fast and we still had some channeling at the end of the shot.

In keeping with our systematic process, the next step is to reduce the dose to 14 grams while retaining the same grind and tamp. In keeping with our formula, if we keep the grind and the tamp the same but reduce our dose, we should get an even faster flow.
That faster extraction should lead to faster blonding and more channeling. So let's see what happens.
«missing video»

Not as dramatic of a transition as I thought it would be. There was still more channeling than the 15 gram shot. The flow was slightly faster then the 15 gram dose and the puck was a little loose after the shot.

Now we need to slow down the extraction. We will repeat the dosing but adjust the grinder one click finer, from 4 to 3.75.

First up is the 14 gram dose, same tamp, and the grinder adjusted to 3.75
«missing video»

The flow has slowed as expected but we are still getting channeling at the end of the shot. The flow is slightly uneven which could be attributed to a slightly off distribution in the basket.

Now for the 15 gram shot, 3.75 grind and same tamp.
«missing video»

Close, so very close. The timing was better but just a little long, the flow looked better but we still had some minor channeling at the end of the shot. At this point the blemish in the shot could simply be caused by a slightly off distribution. I am not accustomed to dosing down so far so what you may be seeing is a flaw in my technique. That is something only time and practice will resolve. The cup looks and tastes pretty darn good.


We have discovered that the Elektra does not like being over dosed, the sweet spot appears to be 15 grams in the stock double basket with this blend and tamp. We have explored 20, 18, 17, 15 and 14 gram dosing and gotten the best shots from the 15 gram dose.

One thing that does bother me is that at 15 grams I am still getting a loose puck. The coffee is not setting against the shower screen. I also notice that at 17 grams I get a fairly heavy impression of the shower screen on the surface of the puck after the shot. With the 15 gram dose I am not getting any impression from the shower screen and my shots are experiencing a problem at the end of the extraction. Missing from this series is 16 grams. Could that be the magic bullet I am looking for? We have gone this far, we might as well be thorough and explore that 16 gram dose. However, that will have to wait until the next installment.

For now I have to get to my Buffalo wings and football game, go Colts.
Dave Stephens

User avatar
cannonfodder (original poster)
Team HB

#17: Post by cannonfodder (original poster) »

cafeIKE wrote:Perhaps the best advice for anyone with a new machine and / or grinder is to plan on binning 2 kilos of FRESH coffee over the weekend to dial in the machine(s). If they've never made espresso before, plan on the same routine for a month. It's important to have a quantity of the SAME coffee. It's crazy to sink a grand or two into hardware and worry about a few bucks worth of coffee.
Exactly why I say one of the variables is the blend and why I am using the same blend throughout the process. Changing the blend is a major change in one of the key variables. The other is time. As we all know coffee grind changes (I hinted at that earlier by pointing out fresh beans take a coarser grind) as beans age. So once you do find that magic combination that works for your particular machine, grinder, and blend, the grind will slowly shift as the bean ages.

Don't get fixated on numbers. Please, don't get fixated on the numbers. The grind and dose are for my blend on my grinder on my machine. Your settings will surely vary, even if you have an A3 and Cimbali Jr. grinder. Settings vary from machine to machine so my 4 may be your 4.75, my 15 gram dose may be 16.5 on your scale. The entire point of this post is to emphasize the need to make small adjustments, one variable at a time. Do not try to adjust your dose, tamp and grind all at the same time. Also keep in mind that distribution makes an enormous difference. Even if your dose and grind are exact, if your distribution is off your shot will not be any good. I actually find getting the dose and grind the easy part. Learning to get an even distribution and fine tuning your technique is the hard part.
Dave Stephens

Dogshot

#18: Post by Dogshot »

cafeIKE wrote:One minor flaw in your method is you used different beans on each test. To test the accuracy of the scale the same beans should be loaded for each test. The variablility of beans probably guarantees on some tests your count would vary ±1 bean.
My explanation was not very clear, but I used the exact same beans for each test (with the exception of the single bean that had to be added for test #3). I agree whole-heartedly with your main points, and my primary purpose in weighing my dose is to waste as little as possible. I use the WDT, and find it a great way ensure consistency in dosing. For me, after stirring the grounds in the basket, sheering off the excess is a consistent under-dose, a single tap is the ideal dose, and 2 taps is an over-dose.

Mark

Abe Carmeli
Team HB

#19: Post by Abe Carmeli »

Steve,

What grinder are you using? If you use the WDT on these shots and these are fresh beans, the chanelling is likely a tamping or a grinder issue.
Abe Carmeli

User avatar
cafeIKE
Supporter ❤

#20: Post by cafeIKE »

cannonfodder wrote:I actually find getting the dose and grind the easy part. Learning to get an even distribution and fine tuning your technique is the hard part.
It's important to have a tamper that allows you to judge level and head space EASILY while tamping. If your tamper piston stands several mm above the edge of the basket its much harder to get a good feel for headspace and level than if the piston edge is just a mm or so above the rim. If the showerscreen is curved, a slight curve on the piston may help. I have to pay much more attention with my flat 57mm generic than I do with my 58.25mm Reg Barber American Curve, mostly for the reasons stated.

The WDT and the M4 are two significant improvements I've made to making espresso. Another, adding an Isomac Gran Macinino as a press & drip grinder. Having an ESPRESSO ONLY grinder is something many overlook. Even if you never recover the cost of the second grinder in coffee, it's well worth it for the reduced frustration. Also clearing the previous shot detritus. These seemingly minor details could mislead one into thinking there is a problem in one's technique.

The Devil is in the Details and there are details a'plenty!

Again, a great write up.
Well worth reading by all.
Thanks for all the effort.