If were going ascribe a benefit to nutation over any another distribution, we should collect some data on basket geometry, tamper face diameter and profile, dose, etc. I don't think I can ever recall seeing a pro do it.

We've all had times when everything was pear-shaped and then miraculously ship-shape with no [conscious] change on our part. [ Or more often the reverse ] Ascribing a benefit when the result may have been self healing is witchcraft.

cafeIKE wrote:If the tamper is canted, it is not pressing the coffee at the basket side. As the tamper goes around the basket it is moving coffee away from the basket side.

That is so with a flat based tamper. Not so with a convex base.

another_jim wrote:It is easier to to use a curved base tamper when doing this.

I think the legendary Illy glass portafilter would be able to help with the geometry via direct observation.

Failing that, tamping into a transparent cylinder of the appropriate size might prove interesting.

My tampers are all flat and I haven't tried a nutating tamp, though I have used the Staub or NSEW tamp.

-Chris

cafeIKE wrote:If were going ascribe a benefit to nutation over any another distribution, we should collect some data on basket geometry, tamper face diameter and profile, dose, etc.

For those cases where it matters, I believe the difference is enough that any impartial observer/taster would not doubt the results. My guess is that this method will only benefit espresso machines that for whatever reason are prone to side-channeling as evidenced by "donut extractions" at the onset of the pour. Some espresso machines are like that. As I documented in Pressure profiles, preinfusion and the forgiveness factor, I accept that sometimes there aren't simple explanations why. *shrug*

Cafe Ike's diagram also presumes a basket with straight perpendicular sides, as opposed to a subtle slope. Sorry, but for whatever reason, it works for me....it isn't nonsense.

I don't need to collect a batch of data for an analysis. I just suggest to give it a try. Depending on your machine, basket, tamper, and technique, it might improve your shots. One size does not fit all.

SwingT wrote:That is so with a flat based tamper. Not so with a convex base.

Um...



A 57mm convex tamper with a 1mm rocker raises the center above the rim at about 4° and if this angle is exceeded, it's still moving coffee away from the edge of the basket. 4° is about 6mm displacement from the center on a 90mm tall tamper.

weasel wrote:Cafe Ike's diagram also presumes a basket with straight perpendicular sides, as opposed to a subtle slope.

The subtle slope on a basket wall is a degree or less. When the tamper is canted, the corner is moved away from the wall. It's quite difficult to maintain the downward force perpendicular to the basket bottom as the top of the tamper gyrates. If the force is not perpendicular, coffee is moved away from the wall, even if the tamper rim could be maintained in contact with the basket wall. Bye-bye 'seal.'

A properly shaped nutation tamper would have the sides cut back so the rim could maintain contact with the basket wall and compress the coffee there. An additional enhancement would have a spring loaded lip to roll around the basket rim to maintain symmetry. When the vertical tamp is applied, the lip would help maintain perpendicular tamp.

FWIW, I've seen some pros move the coffee back and forth with their hands on grossly updosed shots. Perhaps on updosed shots on some basket shapes, there is some benefit to moving the coffee back and forth to force coffee into the basket corner. If nutation accomplishes that, so be it. It may just as well be done by shaking, tapping before tamping, dental vibrator... but 'sealed edge' just doesn't hold water

weasel wrote:I just suggest to give it a try.

BTDT. Nutating with 57-58.5mm flat, C-Flat, 1mm & 2mm convex at a precision probably not considered by most proponents vs. K.I.S.S. show no improvement as has with every other 30#, tap, twirl and voodoo rain-dance.

HB wrote:I accept that sometimes there aren't simple explanations why

That's how we got Climategate, ignoring the science

I hate to argue Ian's ultra-precise reasoning about this form of tamping. After all, ground coffee has perfect geometric precision and transmits tamping force with the accuracy of a well-machined gun barrel.

So I won't dare to contend that a few pounds weight applied at a single contact point near the rim is more likely to close up any faults beneath it at the edge of the puck than 30, or even 100 pounds, applied to the whole tamper bottom. After all, in my ignorance, I thought that a powder would transmit force somewhat sloppily, so that the exact shape of the rim or basket edge or angle of attack would be irrelevant.

False assumptions don't equal science. '1 degree or less'? Hardly, my Rancilio basket has way more than 1 degree. Are all baskets the same? And you've measured them? What is your source for the 1 degree?

What Pro's do doesn't matter. Time is a major consideration for them. What machine are they using? Doubtless not my Silvia. Different techniques may work on different machines, etc. Is their way the only way? I'm sure it works best for their situation, not necessarily mine.....or others.

Voodoo rain dance? Bad analogy aside, it seems some very competent people here have found it useful. Is it possible they know something you don't Ian? I apologize for being personal.

Sincerely, please show a little respect for the opinions of others, even if you disagree.

weasel wrote:Sincerely, please show a little respect for the opinions of others, even if you disagree.

+1.

For what it's worth, whenever I read about this in the past, I chuckled about it's value (sorry Jim). It fundamentally seemed like a bad idea, plain and simple. That was my opinion until I ran across some espresso machines where it demonstrated a clear, unmistakable improvement. It doesn't surprise me that some, like Ian, say it's voodoo/poppycock/baloney because that was indeed my own experience with a wide range of equipment. Again, in my experience, the main benefactors are espresso machines with a propensity to side-channel.

For those following this thread, my recommendation is that the next time you see a "donut extraction", give it a try. If your espresso extractions are already orderly, I doubt you'll see an improvement in the cup. That said, apart from some of the snippy comments above, I'm glad Adrian raised the subject. This thread has piqued my curiosity and I will try to remember to retry it with less fussy equipment.

I'm still somewhat puzzled how nutating is supposed to waste time. I spend less than 3 seconds going from the loosely filled basket to ready to pull. I'm not aware of any faster method for distributing and leveling the puck; the various barista competition moves like stockfleth's or intelly chops, etc, are slower.