Mazzer Mini stops grinding coffee

Grinders are one of the keys to exceptional espresso. Discuss them here.
badmajon
Posts: 18
Joined: 10 years ago

#1: Post by badmajon »

... apparently, you can't increase grind fineness when the machine isn't either empty or running. It just jams somehow and won't spit out any coffee.

Why is this? It's really irritating!

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HB
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#2: Post by HB »

You can move the setting slightly finer without jamming, say one notch or so. But to answer your question, there's a layer of trapped grounds between the burrs; when you move them closer together, the grounds are compressed. At some point, the grounds will provide enough resistance to prevent the motor from starting. Grinders have a capacitor to give the motor some extra ommph on startup, so it's unwise to let the motor stall. You can adjust coarser without issue since that increases the space between the burrs.
Dan Kehn

badmajon (original poster)
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#3: Post by badmajon (original poster) »

Hello, it doesn't jam the motor, the beans just stop going down and it stops grinding coffee. The burrs are still turning as far as I can tell.

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HB
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#4: Post by HB »

Oh, I haven't seen that happen with a Mazzer. While unlikely, it's possible that the burrs are coated with coffee tar, especially if you're grinding lots of oily beans. That can lead to the symptoms you describe. See Cleaning a Mazzer Mini (and just in case, read Mazzer reassembly problem after burr replacement to avoid any mishaps).
Dan Kehn

Nate42
Posts: 1211
Joined: 11 years ago

#5: Post by Nate42 »

I've actually seen something similar a few times with my mini. My wife for whatever reason never could wrap her head around the idea that she couldn't adjust the grinder without running it, so she jammed it up a few times. I think maybe coffee is getting compacted into the part of the burr that feeds new coffee in, allowing them to still spin but not pull in new beans. In any case, going coarser until it starts to work again and then taking care to only make large adjustments while running always solved the problem.

The basic idea that you should run the grinder while adjusting is common to ALL grinders BTW, and is not a quirk of the mini. In fact, lesser grinders can be damaged by doing this, mazzers fortunately are fairly bulletproof.

erik82
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Joined: 12 years ago

#6: Post by erik82 »

Same happened to me when borrowed a Mini for a couple of months while awaiting the HG One. With some beans and really fine grind setting the Mini stops spitting out coffee and the grounds stay in the grind chamber. Turning it coarser until it start to spit out grounds again is the solution. After that you can set it finer again.

Apparently, with some very fine grind settings, the backpressure will increase to a point where the Mini isn't able to spit out the grounds and they stay in the grind chamber.

If you google the problem you'll find that on HB and Coffeegeek there are more people having this problem. My Super Jolly never had this problem so it should be a Mini problem.