Grind consistency of column with weight vs. stock hopper - Page 4

Grinders are one of the keys to exceptional espresso. Discuss them here.
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cafeIKE

#31: Post by cafeIKE »

Today 3 x 10.5 -> 10.4, 10.4, 10.1

Just for grins checked scale calibration 10, 100, 500 -> 10.0, 99.9, 500.0

mitch236 (original poster)

#32: Post by mitch236 (original poster) » replying to cafeIKE »

Could you be losing some grounds to the countertop? What I'm having difficulty understanding is where are the lost grounds going? Even if you only lose 0.1 gm per shot, after 100 shots, there should be 10 gm of grounds somewhere.

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cafeIKE

#33: Post by cafeIKE »

±0.2g is accountable due to weighing vessel change and scale accuracy. I could remove a bit of error by weighing the beans in the basket rather than a yoghurt cup. It's entirely possible there is some non-linearity in the cheep-and-cheerful scale exposed by weighing the beans in a 7.5g yoghurt cup and the grounds in a 25.4g basket. 10.3 ± 0.2g accounts for the minor variations. Still searching for the 2g consumed on the first two shots yesterday. :shock:

At around 30 shots a week, if 0.1g per shot / 3.0g is heading to the counter top, the missus would have let me know about it. :evil: Never weighed it, but after a week, there might be 0.5g spread across the catch tray.

mitch236 (original poster)

#34: Post by mitch236 (original poster) »

The reason I don't believe in taking apart a grinder and cleaning all the nooks and cranies is because those spots fill up on the first few shots and stay there until something knocks them out. Maybe that 2 gm lost yesterday was following one of the nooks giving up its old grinds on a previous shot and needed new grinds to fill it again.

Your account of today's weights seem more in line with what would be expected.

mitch236 (original poster)

#35: Post by mitch236 (original poster) »

I had a couple of hours and three bags of fresh Apollo so I did a comparison between single dosing and leaving a few inches of beans in the column. My unscientific result is that while the taste wasn't much different between the two approaches (which may be due to my unrefined palate) but the look of the pours were better with the bean column (leaving a few inches in the column).

I measured my waste using this approach. The most I could waste (that means worst case scenario -having the chute full) was 20 gm. A lot, I know but at this point, I'm willing to lose that amount to get better consistency shot to shot. If I'm careful grinding, I can reduce this amount to about 4-5 gm.

Again, I am still in my learning phase so things may change in time!

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cafeIKE

#36: Post by cafeIKE »

mitch236 wrote:The reason I don't believe in taking apart a grinder and cleaning all the nooks and cranies is because those spots fill up on the first few shots and stay there until something knocks them out. Maybe that 2 gm lost yesterday was following one of the nooks giving up its old grinds on a previous shot and needed new grinds to fill it again.
Andy and Vince should start working on a Cran'oNookyScope :P

Previously Scale Dynamic Instability

EDIT : scale is 1000g, not 500g
The scale now in use is a 1000g similar to this 500g from Deal Extreme et al.

This morning I checked weighing the same '10g' beans in the yoghurt cup vs the basket.
On a series of 5 tests : 9.9 ±0.1g

Dribble the beans vs dropping a dollop
On a series of 5 tests : 9.8±0.2g

Scale On, Tared, Weigh vs On - wait 20s - tare - wait 20s - weigh
On a series of 3 tests : 9.7 ±0.3g

Bottom line, over the course of a week, dropping 'summbeenz' in the weighted mini-hopper, a short 0.5g purge and timed grinding of 4.3s yields shots every bit as consistent as weighing single doses. In a fraction of the time and a grossly tinier PITA... :wink:

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Peppersass
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#37: Post by Peppersass »

You need to get a better scale, Ike.

Neither of my My-Weigh scales shows as much inconsistency as your scale.

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cafeIKE

#38: Post by cafeIKE »

Investigating further, the cause of the error is due to battery voltage. With fresh alkaline @ 1.6v, the variance is ±0.1g. The batteries in use at the time measured 1.445v, still well into the 'green' on a battery tester and well above the LOW BATT indicator.

Battery voltage variance is a very common problem with modern battery operated electronics. All to often the circuits have inadequate isolation and the LOW BATT indicator illuminates well after the minimum accurate voltage is passed.

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michaelbenis

#39: Post by michaelbenis »

another_jim wrote:It leaves me scratching my head. For the moment, I don't think experimenting is much use, since I can't think of a hypothesis to test which would explain the differences we are seeing. If we dd have something to test, we could do it, since Sherman has a K10 like mine, and we could set one with a hopper and one for single dosing that produced the same shot dose/flow characteristics.

Mitch appear to like very light, acidic roasts that I mostly find somewhat unbalanced; so one possible hypothesis is that single dosing == hopper for beans and roast profiles common in espresso, but not for the tight rope dancing roasts he likes.

Suggestions?
I think it is entirely possible that bean and roast and indeed extraction ratio preferences come into it as well as particularly elusive sensory trips one may be looking for in flavour nuance or mouthfeel. But the grinder is crucial. It certainly appears that the dosered K10 is one of the best choices for single dosing, turning slowly and popcorning little, whereas the Elektra Nino works very much better when used as designed to be. The Pharos, of course, as a hand grinder, is a happy single-dosing animal...
LMWDP No. 237

mitch236 (original poster)

#40: Post by mitch236 (original poster) »

I've been thinking a lot about why the pours look better when I use columned beans as opposed to single dose. I think it comes down to this; at the beginning of grinding, the grinds are very consistent. As the grinding gets to the end and the beans aren't grinding as consistently, the part of the pf that the end of the grind grounds land pour faster than the area of the pf that got the beginning of the grind. It might only account for a couple of grams but it definitely affected the look of my pour and caused some consistency issues. I don't think the fact that some of you can make it work depends on the K-10 as compared to the Robur with the auger (since both have slow rotation and not much popcorning). I think the fact that Jim and others are better baristas than I am accounts for the difference. I wish Jim would do his grind analysis again using the VST basket (which is much more consistent basket to basket). I would like to know the differences between my single dosing and hopper. I have to tighted the grind by around 4 notches to get the single dose to pour about the same as the hopper doses.