Nutation is not tamping - it's distribution

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RapidCoffee
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#1: Post by RapidCoffee »

Thread subject says it all. The so-called nutating tamp is not a tamp, it's a method for distributing grinds more evenly in the basket. Nutation uses the tamper to accomplish this redistribution. It is generally followed by an actual tamp, which applies pressure directly downwards onto the puck with the tamper.

I suggest we stop using the term "tamp", and simply refer to this technique as nutation.
John

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#2: Post by Nunas »

Interesting post. I agree that nutating is not tamping, at least so far as the technique was originally intended. Although, I was not aware that there is any confusion between the two techniques. But this does raise in my mind a related issue.

I used to nutate as part of my regular routine, ever since I saw a video of a professional barista doing it. I don't any more. I guess it's the engineer in me, but one day I found myself asking, "Why am I doing this?", which led me to think about what was happening to the puck. My conclusion was that while it probably does help distribute the grounds somewhat, the distribution cannot possibly be even and it inevitably it must lead to an uneven tamp. As the tamper is rocked around, the outside grounds receive more tamp then the inside. In essence, we are creating a mound of coffee, compressed at the margin and less compressed in the middle. The actual tamp, then must not just compress the puck downwards, but it must also force the mound of grounds outwards against the already compressed margin.

So, I would argue that nutation is not only 'not tamping', it isn't even a good means of distribution. Although I stopped using WDT too, I'd argue that as a grounds distribution technique it is superior to nutating.

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#3: Post by Espresso_Junky »

Opinions vary... Hilarious that some seem to think there is a right/wrong way to do things. What works for YOU is what matters and who cares what others think anyway?!? I nutate as part of the tamping process, not distribution. Gives me a much better sidewall seal.

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#4: Post by bluesman »

Nunas wrote:My conclusion was that while it probably does help distribute the grounds somewhat, the distribution cannot possibly be even and it inevitably it must lead to an uneven tamp. As the tamper is rocked around, the outside grounds receive more tamp then the inside. In essence, we are creating a mound of coffee, compressed at the margin and less compressed in the middle. The actual tamp, then must not just compress the puck downwards, but it must also force the mound of grounds outwards against the already compressed margin.
I suspect there's a lot that we don't know yet about the physics of tamping. A significant and growing body of evidence says that finely granular solids behave like liquids under many circumstances, including pressurization. Sand even forms droplets when released from a funnel (see this paper). Fluids are incompressible and assume the shape of their container - and pressure is distributed evenly throughout a fluid in all directions.

The concept that ground coffee in a closed space behaves like a fluid supports what I've always believed, namely that tamping shifts the grounds around until they're mechanically locked together and can no longer slip over or around each other (the state we refer to as maximum compression). The more regularly and smoothly ground the coffee, the longer a fluid state will persist before the grains "lock" and become a solid (and the higher the effective tamping pressure can be). If this is true, both nutation and the "north-south-east-west" approach accomplish the same thing. Further, different grinders must produce different shaped particles that adapt themselves in different ways to pressure equalization. And if this is correct, there actually are better grinders - but different beans grind differently, so some grinders may be better for one bean than another.

Pressure equalization might then be a factor in distribution, and the mechanics of the grind may make different coffee/grinder combinations behave totally differently when tamped. Fascinating!!

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another_jim
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#5: Post by another_jim »

Nunas wrote:I used to nutate as part of my regular routine ... while it probably does help distribute the grounds somewhat, the distribution cannot possibly be even ... the outside grounds receive more tamp then the inside ... creating a mound of coffee, compressed at the margin and less compressed in the middle
Yep. And if you use a curved tamper, that's a good thing. With a flat tamper, nutating is hard, since the edge of the tamper grinds against the basket, and also somewhat pointless. If you need a fast distribution move with a flat tamper, Stockfleth's is probably best.[vimeo][/vimeo]
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#6: Post by F1 »

Is it ok if I call it Brobdingnagian? Am I gonna get an earful? :lol:

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#7: Post by bluesman »

F1 wrote:Is it ok if I call it Brobdingnagian?
Only if you do it Swiftly......

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#8: Post by RockyIII »

I used to do a nutating tamp when I had a Londinium. I did it with the tamper after WDT.

Rocky

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#9: Post by Nunas »

Stockfleth's is probably best.[vimeo][/vimeo]
Jim, there was no video in your post. But, I looked up 'Stockfleth', as I've never heard of it and found a video. Well, what-d'y-know...I did something very similar for years. But, when I got my Esatto (and now my 7-270W), I gave it up, as it usually results in knocking off some of the meticulously weighed grounds (at least the way I did it). I also used to thump my portafilter on the side of the counter to nutate, then when I got a tamping mat I thumped down on the mat. With the 7-270W the grinds come out so fluffy that I've mostly given up all of the above. Apart from a tiny vertical thump to settle the grinds a little, I just tamp. Seems to work fine for me...or maybe I've just got lazy :)