drdna wrote: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.

I'm either confused by what you're saying here or not agreeing with it; I can't tell. My impression of a 'nutation' or 'precession' is that you're using the convex curve of the tamper base to press a convex (rather than concave, which is what you'd get with a level, normal tamp) shape with an elevated 'ring' around the edge where the tamper doesn't press (as illustrated by Ian's diagrams). Then when you tamp normally, you press a convex tamper down on a convex mound:



It strikes me that pressing this makes for a tamp that ends up compressing the puck laterally as well as vertically, and this is what I always assumed fixed the side channeling ('sealing' sounds like a very imprecise but usable word for this). Maybe I'm just a witch-doctor, though?

Nice drawing, Nicholas. That's how I understand what's happening.

Just a thought : Is nutation more beneficial to left leaning thwackers than down droppers?

If I use the doser on the MXK, or its predecessor the CMH, basket distribution is sometimes a little lopsided. At those times I'd angle the tamper to 'shove' the coffee over and then bear down vertically.

Does it matter if we nutate clockwise or counter clockwise? What if we are in the northern or southern hemisphere?

cafeIKE wrote:Just a thought : Is nutation more beneficial to left leaning thwackers than down droppers?

If I use the doser on the MXK, or its predecessor the CMH, basket distribution is sometimes a little lopsided. At those times I'd angle the tamper to 'shove' the coffee over and then bear down vertically.

I'm not sure of the utility of nutation at correcting dosing 'flaws' such as a left-throw or any other off-center dose. It strikes me that if this is the problem, the solution is to move the portafilter to get a centered distribution, or using side-tapping (you do this, right?) or finger-leveling to correct the problem. Angling the tamper as you describe might work, though. I've never played with that. The classic use of the technique, though, seems like it's ideal as a solution to donut extractions, where the distribution is centered but maybe center-heavy. I don't see any reason to doubt that it's good at this, based on my experience, and my strong inclination is to think that pushing straight down on that mound that you create pushes it outward neatly. I don't know if that helps with 'basket adhesion' or it just plain causes sufficient outward (from the center) redistribution to give channel-free pours.

Now would be an AWESOME time for the jokers running La Spaziale to POST THEIR STUPID PERSPEX PORTAFILTER VIDEOS to Youtube. It strikes me as potentially useful for studying things like this... man, I'd buy one of those in a second if it were available. For my part, I'm boycotting La Spaziale until they do. Man, you'd think 4 years would be long enough for them to figure out how to use the internet!

Because of my respect for Dan and Jim, I will take it on faith that the nutating tamp was indeed helpful for the Dalla Corte Mini. However, I have never observed any appreciable effect, either positive or negative, of a nutating tamp. This holds for a wide variety of baskets and doses on a 58mm E61 Vetrano, a 53mm Spaz S1, and a couple of 49-51mm lever machines. The nutating tamp also failed to make a noticeable difference with different grinders (flat vs. conical burr Mazzers), different coffees, different (flat vs. convex) tamper pistons, and different phases of the moon.

I'm with Ian on this one: any benefits of the nutating tamp are more likely to be associated with a subtle redistribution of coffee grinds, not an edge sealing. If the distribution is correct*, any reasonable tamping style seems to work just fine.

* Of course, I'm assuming other espresso parameters (grind setting, dose, brew pressure, etc.) are correct as well.

I have a Mini Vivaldi 2 and have been using a nutating tamp for 1 1/2 years. At the time, my impression was that it pretty much cleared up any spritzers I would have. I'll try some comparisons again. This thread raised my curiosity. Michael

RapidCoffee wrote:I'm with Ian on this one: any benefits of the nutating tamp are more likely to be associated with a subtle redistribution of coffee grinds, not an edge sealing. If the distribution is correct*, any reasonable tamping style seems to work just fine.

Um, the nutate part distributes and grooms the edge.

Take basket/PF directly from the grinder, grounds untouched,
-- then nutate,
-- then press lightly,
-- then make the shot.
If you do any other sort of distribution, it's a complete waste of time.

How about this for a theory, instead of forming a better seal to the basket wall. How about if it creates a denser ring of compacted coffee that lets the water through slower just before the wall and lets the grinds expand against the wall slower. This may or not make a better flow near the wall, but would also tend to drive the water into the more centered grinds.

It would be almost a preinfusion for the walls.

That would decrease the tendency for doughnut extraction. With the problem that the wall grinds would be under extracted.

-Cecil

It sounds like you're describing a redistribution of grinds. Also, if you have donut extractions, the perimeter of the puck is badly overextracting; in this case nutation or some other appropriate redistribution method should correct this flaw for even extraction. If you over-pack the perimeter using the method, then you get center channeling. That's purely hypothetical as I've never seen nutating do so, but if you manage to do this, I'd say it's a clear matter of "you're doin' it wrong." The idea is to correct without over-correcting, regardless of the redistribution method you use.

But think about it, all nutating is doing is compacting some grinds and moving others to the outside walls, as well as others to the inside. Those on the walls are not getting the pressure, only the ones under the edge of the tamper. If you make a offset coin round type of tamp you are not tamping the walls, but the grinds just inside the walls. Think about where the real downward force is placed. Yes there is some outward displacement, but it is at a tangent to the real force.

-C