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SwingT wrote:I am doing a "wobbling" rotating tamp similar to the video, slightly more wobble maybe, but quite similar to the video.

another_jim wrote:precession is 2D physics, the simple rotation of the axes of an elliptical orbit; while nutation is 3D analytical geometry, the motion of a tilted annulus touching a plane at one point and having its axis describe a circle parallel to that plane. This motion will inscribe a circle on said plane whose radius is the cosine of the tilt angle times the radius of the annulus.

Well, so the dictionary says about precession: "a gyration of the rotational axis of a spinning body about another line intersecting it so as to describe a cone" to make it a bit more clear. This is the motion I believe is seen in the video and describing above as "wobble"

However, this is NOT what I meant when I said "wobble." Instead, I am referring to fluctuation in the degree of precession, so that rather than describing a circle projected upon a plane, one would describe a cogwheel sort of shape. This "wobble" is nutation.

I have no problem with the phrase nutating tamp, but I want to be clear on what we are all doing. I think if it is done properly it is a fast reliable way of leveling the puck. If done improperly it can lead to channeling and even crack or dislodge your puck.

'do as I do, not as I superfluously interpret an ambiguous word to create imaginary confusion about a well-understood technique?'

EDIT: Not to be belittling, I'm just trying to be a little light-hearted: it sounds like a "precessing motion" might be a more technically accurate term for the action (I thought "coin roll" was a much more accessible term, though), but that nutating is probably an acceptable if rather ambiguous term that would certainly be technically inaccurate if tamping were in the realm of astronomy. My point was that I think the uncertainty and concern that you've raised is perhaps a result of poorly interpreting the word, to whit: There may be 3-4 different definitions for 'nutation,' but given the previous discussion and video re-posted by Dan in this thread, I don't see any basis for thinking people were confused about the technique itself.

As a matter of interest, though, if anyone is having difficulty understanding Adrian's contrast of precession and nutation within astronomy and physics, here's a couple of nifty animations from this site:

precession I, precession II
precession + nutation I, precession + nutation II

I actually think that visually, the 'wobble' animation strikes me as the most accurate to what I've understood a 'nutating motion' to be w.r.t tamping technique. I think part of the trouble here is that these terms seems to be defined in relation to spinning bodies like gyroscopes or orbiting heavenly bodies, which a tamper is not (implicitly).

Jim, did you have any idea what you might have been getting into when you named this?

About a day after Ted Simpson described it, and I supplied the name, 2002 on alt.coffee, I think.

The discussion was about Staub's NESW tamp. Ted said he has seen some people circle the top of the tamper in a motion like a ship's mast on a rolling sea. I remembered flow meters that looked like wobbling coins that never settled, "nutating disk flow meters," and supplied the name. Maybe a marketing type should start a list of vaguely naughty sounding, geeky names; they are memorable.

If 'sealed the edge' had not been mentioned, I'd probably have ignored the thread.

another_jim wrote:After all, ground coffee has perfect geometric precision and transmits tamping force with the accuracy of a well-machined gun barrel.

'sealed the edge' indicates concurrence, no?

Unless we endeavor to understand the result of our actions, making espresso will devolve into puckology. Nutation is a distribution bandaid modifier. No magic. Anyone who wants to nutate, go ahead. Just understand what is happening. With knowledge, improvement is possible. In ignorance, we'll start seeing chicken bones atop the group.

I'll see your 3s and raise to 500ms for a side to side shake & rap.

another_jim wrote: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.

Well, I'm a lot newer than most in this thread, (or on this forum, for that matter) but I have quickly become an adherent to "less is more" for practical purposes. I'm thinking that the quickest, easiest ( and probably fastest) way that I can tamp is probably going to be the most consistent, and for me the best.

Every time I remove some "procedure" from shot pulliing "ritual" my shots improve

So, I'm more of a proponent of "less is more" than I am of Nutating. I'm going to have to try pulling some on the vivaldi without nutating, and see how it goes.

shadowfax wrote:'do as I do, not as I superfluously interpret an ambiguous word to create imaginary confusion about a well-understood technique?'

Maybe.

As you know, I like to bring up topics that make people think about what they are doing. I am also a bit anal-retentive or as I prefer to describe it meticulous.

I actually just wanted to make sure that everyone was on the same page regarding this technique, because I feel that is the foundation for a good discussion.

I use the nutating tamp because I feel that simultaneously compressing evenly across the puck is nearly impossible. Either you get a tamping machine that can constantly adjust for tamping pressure across the puck and re-level itself or you develop a technique that applies asymmetric pressure in a systematized way. Hence the nutating tamp.

Also I worried that simultaneous compression would increase the sideways pressure in the puck and predispose to channeling. By spreading out the pressure changes through nutation, the risk may be lessened.

SwingT wrote:I'm going to have to try pulling some on the vivaldi without nutating, and see how it goes.

I also use the Vivaldi. My experience has been that two methods are best, the nutating tamp and the four-points tamp (in which I rest the tamper on the grounds and use both thumbs and index fingers at four equidistant points on the rim to slowly compress the puck in a level fashion). Both are equally good for me.

Other opinions for Vivaldi owners?

NUTation challenge :

Nutate half way round and then do the level tamp. There should be a definite difference between the halves.

I have found that a turkey wishbone works much better than the chicken bones BTW. I think the larger bone structure pulls the coffee into a cone much more evenly.