Mazzer Mini: detecting where the burrs touch?

by GM on Wed Aug 18, 2010 8:51 am

Hello,

I'm trying to dial in a new machine (Isomac Zaffiro) and finding I need to grind really fine... I'm getting nervous that I might go too fine and damage the burrs, or some part, of my Mazzer Mini E.

So, I have some simple questions:

- will it be completely obvious to me when I get to the absolute zero point of the Mazzer Mini? I sometimes hear a slight high pitched whirring sound when adjusting finer --- is that the zero point?

- is there some chance my grinder has become decalibrated? The current setting is a looong way finer than the factory sticker, and grinding anywhere near the sticker point yields nothing but superfast gushing pours.

Many thanks in advance for any help you can offer,

Guy.

by HB on Wed Aug 18, 2010 9:04 am

See How to find the grinder true zero point for discussion. The exchange excerpted below from another thread elaborates on this point:

HunkaBurninLove and HB wrote:Q. I was trying to find the "zero point" but wasn't sure if I really found it. Turned on the empty grinder and slowly adjusted the collar until I heard what appears to be the burrs touching. The sound reminds me when you get a key made, so I assume this is it? I didn't want to go any farther for fear of damaging the burrs.

A. Yes, the sound you describe is very apt. You can also clear the grinds from the chamber, turn the grinder OFF, and then turn the dial hard counter-clockwise to find the zero point. However, the factory setting is an accurate "start here for espresso" setting. I don't think that I've drifted more than 1/2" away from it in either direction (though to be honest I removed it long ago).

However, judging from your description, I'm wondering if either (a) the coffee beans are stale, or (b) you're turning the grind adjustment the wrong way - remember, counter-clockwise = finer.

My first recommendation is to start with a known reliable coffee that is marked with the roast date. Ideally pick one you know well (e.g., from a good nearby cafe). If that's not an option, there's lots of online coffee roasters. Of the HB sponsors, Intelligentsia Black Cat, Counter Culture Coffee Toscano or Caffe Fresco Ambrosia are frequently mentioned as forgiving blends to learn on. The Coffees forum has a number of threads offering other recommendations. My second recommendation is to assure your grinder's setting is in the ballpark by reading the tips in Fine tuning grinder setting with minimum waste, specifically this post.

by GM on Wed Aug 18, 2010 10:46 am

Dan,

Thanks for your near-instantaneous reply and the linked threads.

I can say for sure that I'm not turning the wrong way. I've been using this grinder for several years with my Pavoni Pro and am quite used to adjusting the grind. But, I am shocked at what I'm needing to do to prevent pure gushing flows from my new Zaffiro.

The beans are if anything too fresh: roasted two days ago by hasbean (I'm in the UK.)

I am kind of baffled by the need for fineness, but I think that is a topic for another thread: there must be something else to correct in my technique, equipment or coffee.

Guy.

by HB on Wed Aug 18, 2010 10:54 am

GM wrote:But, I am shocked at what I'm needing to do to prevent pure gushing flows from my new Zaffiro.

Do you have a bottomless portafilter? If the coffee fineness passed the "pinch test" described in the linked thread, my suspicion is channeling. You could reduce the brew pressure to increase your margin of error, however keep in mind that higher than normal brew pressure will not cause channeling if technique is spot on. See the threads linked under Vibratory pumps in the Espresso Machines - FAQs and Favorites for the relevant discussions (notably I still don't get it: Why adjust the OPV?)

by GM on Wed Aug 18, 2010 4:11 pm

I don't yet have a bottomless PF but will get hold of one for sure.

There is some progress to report and a further Mazzer-related question to ask.

I tested for absolute zero with the grinder off, as suggested in your quoted post above, and found I had plenty of room to spare, so set about dialling in again with less fear.

My first attempt choked the extraction (just a few drops in 15s, and no flow developing); two notches coarser led to a fast pour (50ml in 16s); one notch down again and I got a very well-timed double pour (50ml in 27s from a 16g dose) and a pretty well-balanced shot.

Follow-up question: does one notch between choked and "normal" flow sound right? It doesn't leave much wiggle room for producing ristrettos!

Thanks again.


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