Help : varying flow

[Dego]

Hi
First post here!
I bought an appartamento and an eureka mignon grinder. Have neen using the same beans, black cat, for a while. Found the right grind setting and got some 25 sec shots. despite always doing the exact same routing (distributing and tamping with same pressure) the flow varies a bit, which is ok. My issue is that now the flow rate is too slow and shorts are getting to 35-40 sec. Nothing has changed. This happened before and I had to adjust the grind setting to courser and progressively went back to the same number that I was using successfully but that now is giving me trouble again.
What could explain this change? Could the pressure of the machine fluctuate?
I don’t think it’s the beans. It started happening within the use of the same bag.
Any technical or technique explanation for this? I am just curious and trying to avoid trashing too much coffee…
Thanks!!!’

 

[Musicphan]

Usually, it's the air temp and humidity... its not abnormal to have to adjust the grind size. Another impact could be water pressure if a plumbed in machine but that's usually not the reason.

 

[shadow745]

Yeah lots of constantly changing variables involved with espresso. IMBHO it's never mastered as something will change to affect daily dialing in and keep you somewhat guessing regardless of equipment, skill, etc. For me that's part of the enjoyment as it never gets boring and usually some off the wall process will give an outstanding extraction you will remember for years and try feverishly to replicate.

I really push things most days though as I home roast and some mornings will use 2-3 different coffees. Doing that with a hand grinder that needs adjustment changes for every different coffee type and the grind output will change depend on speed, angle I hold it during grinding, etc. Not to mention slight differences in dose depending on the coffee origin, roast level, grind fineness, etc. As well as slight changes in water temperature at times. Still get mindblowing ristretto extractions that defy common (lame guideline) logic, just the way I like to push the limit.

 

[addertooth]

Don't rule out that the Burrs in your grinder are getting loaded (with debris, especially true for oily beans), and taking smaller bites of the bean (resulting in a finer grind).

I have disassemble and clean my burrs from time to time on my grinder.

Also, calcium can build up in the "boiler" in your coffee maker, which can reduce flow rate, or reduce the rate in which it can produce water heated to the desired set temperature.

In that case, de-scaling may address that issue.