Hopper fed grinders, first few doses run faster?

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HBchris
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#1: Post by HBchris »

I dont have experiences with various grinders, just the Mahlkonig Peak so hoping others can shed some light if this is typical of all grinders when hopper fed.

Where, first few doses of a given bean will run faster (all at the same grind setting)

For ex:
If I complely finish all the beans in the hopper, and grind out all the remnants until nothing left. Then put in a 12 oz bag of different beans in the hopper.

For this example, lets say I had it on grind fineness of: 3
if i ran 4 back to back shots, using the same prep.

The first shot might take: 22 secs to get to desired weight
2nd shot: 26 sec
3rd shot: 29 sec
4th shot on all 29 sec and dead on consistent

With no adjustment to the grind setting.

So essentially the first few shots are running as if a coarser grind.
I know this will tend to occur on the last dose (because of the lack of bean weight). But not sure why it would occur on the first two doses, maybee becuase grind chamber is initially empty? curious if others experience this phenomena when using a hopper. If so, any good workaround with the intial doses (updose 0.5 - 1 gram to offset?)

samuellaw178
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#2: Post by samuellaw178 »

From my own experience with other grinders(including K30 & Robur), the resistance/back pressure from chute does affect the grind size - more resistance = finer grind output...so your observation is definitely not unexpected.

To avoid this, load the hopper before the grinder is empty and starts clearing its chute?

HBchris (original poster)
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#3: Post by HBchris (original poster) replying to samuellaw178 »


So you are saying, once i stop hearing it grinding beans and it is just starts clearing the grind chamber (rather than clearing this all out), to dump in my next bag of beans?

Wouldn't this cause some intermixing and therefore tasting/shot inconsistency with the new set of beans i put in?

samuellaw178
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#4: Post by samuellaw178 »

HBchris wrote:So you are saying, once i stop hearing it grinding beans and it is just starts clearing the grind chamber (rather than clearing this all out), to dump in my next bag of beans?

Wouldn't this cause some intermixing and therefore tasting/shot inconsistency with the new set of beans i put in?
Actually even before that - add the beans before the hopper gets too low and starts affecting the grind size. When used this way - at least the last few doses of your old bag won't be inconsistent. If the beans between bags are quite similar, the grind size wouldn't be too different. That's how I use the K30 and stayed on the same setting pretty much. If I use two completely beans with vastly different grind size, then I am screwed. :P

Even if we allow the chute to run clear, there will still be some old residue in the chamber. The intermixing is the nature of hoppered grinding (think of it as a new way of blending your SO, or creating a new blended blend :D ), which is why many preferred single dosing despite more work involved. Otherwise, we'd just have to put up with the waste...

If you empty the chute, your first timed dose will be off by 6-8g. I just cleared my chute & hopper on K30 this morning and have observation similar to yours (faster flow the first shot).

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radudanutco
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#5: Post by radudanutco »

samuellaw178 wrote:From my own experience with other grinders(including K30 & Robur), the resistance/back pressure from chute does affect the grind size - more resistance = finer grind output...
that sounds quite interesting for me, as I was considering only the empty hopper effect, quite pronounced with my previous Bezzera BB005 (48mm conical) and almost unnoticed with Macap M7 900 (75mm flat) in single dosing;
however, I am working for more than a year by grinding 101g in the Macap doser, then cleaning the path (brush, pulse and Giotto pump), so I can have 5 x 20g+ weighted doses with a minimum of less than 0.3g overall retention...plus, the benefit of having a cleaned path grinder at the end of the session;

still I was concerned - but I haven't checked it - about the last, say, 5-10g of popcorning beans, as giving fewer fines, and I took this mixing of all 100g in the doser as a way to dissipate the effect;
or, it seems to be the other way around (?) - last, perhaps, 20-30g are coming with more fines (at least, the chute is completely stacked at the end), for an overall positive effect (for me, I mean...)

samuellaw178
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#6: Post by samuellaw178 »

radudanutco wrote:that sounds quite interesting for me, as I was considering only the empty hopper effect, quite pronounced with my previous Bezzera BB005 (48mm conical) and almost unnoticed with Macap M7 900 (75mm flat) in single dosing;
however, I am working for more than a year by grinding 101g in the Macap doser, then cleaning the path (brush, pulse and Giotto pump), so I can have 5 x 20g+ weighted doses with a minimum of less than 0.3g overall retention...plus, the benefit of having a cleaned path grinder at the end of the session;

still I was concerned - but I haven't checked it - about the last, say, 5-10g of popcorning beans, as giving fewer fines, and I took this mixing of all 100g in the doser as a way to dissipate the effect;
Doser certainly mitigates the effect by its mixing action. Would be interesting to confirm by capturing the three portions (early, middle and end) and brew separately. I did that a while a go in single dosing mode and the flow rates were very different for each portion. As long as the grind is mixed afterwards(with the corrected grind setting relative to hopper-grinding), the effect on taste is non-existent (at least to me).

When you say the effect is not-noticeable on the Macap, do you mean you can almost use the same grind setting for both single dosing & hopper grinding?

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radudanutco
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#7: Post by radudanutco »

samuellaw178 wrote:... When you say the effect is not-noticeable on the Macap, do you mean you can almost use the same grind setting for both single dosing & hopper grinding?
well, 'almost unnoticed'...
however I made a comparison between:

- an entry-level conical grinder used on-demand (BB005, with the timer it had), which was giving me gushers with the last grind dose; but also this
grinder (100W motor) was quite difficult to use with some high grown large beans (I remember Kenya, Colombia) as I had to re-dial all the settings: the grind was completely biased toward high flow when keeping the previous setting - meaning probably, less fines;

- the Macap M7T 900R, on which I am using very small deviations from a basic setup position, and this mostly for controlling a target flow rate modification, not adapting to a certain roast/varietal...
and I am using a kind of a single dosing: that is I am loading in a small hopper - some plastic funnel - only the required 'dose' for a full 5 doubles session; so, I am losing the definition/clarity in evaluating the effect of last double dose;

not to consider the Strega abilities in adapting the shot procedure to the grind variations, if there are any:
differences in grind particle size distribution are reflected on the full pump pressure ramp: the puck saturation begins at 3 bar, or say, at 9 bar, and I can adapt the follow up procedure to this PI ending: skipping immediately to springs, or retaning the lever for reducing (the pressure and) the flow rate...