another_jim wrote:Abe Carmeli is visiting, and choked a shot using the same coffee, grinder, grind setting, weight, and machine when it flowed fine for me. I nutated then did a pro forma 2 pound tamp, whereas he nutated then did a heavy 30 pound tamp.

As James and Nicholas observed, nutating tamps can have unpredictable effects. That's why I prefer to call them by their more accurate name, "mutating tamps."

Also, that's why I'm trying to train myself not to use them anymore.

I have a question somewhat on topic...

For a non-PI machine, such as my bz07 - would a bit firmer tamp/standard 30# be helpful in preserving the coffee bed? Every since I read a post from OE about them dreading "full brew pressure slamming the puck" in reference to pump machines, I can't help but think of it every time I hit the brew button

King Seven wrote:However, I've seen shots slow waaaaay down when nutating quite aggressively in the tamp. Which kind of freaks me out.

If that were happening to me, I'd suspect that I was having issues sealing the puck to the sides, and getting some side channeling all around the edge. But since it's you... yeah it freaks me out a little as well.

I did notice, however, that tamps on the lever *(Gaggia Factory) tend to reflect themselves consistently in the pressure required to mash down the lever handle. If I tamp hard, it takes more weight to get the same flow as if I tamped lightly. Not a bunch, but noticeable.

My espresso started to become more consistent when I switched to a "consistent" lighter tamp with finer grind.

At a common sense point of view its quite clear you can get the results. Its all about how much resistance there is for water travel through a certain path. When I realized this I experimented with a lighter tamp and finer grind a used taste as a measure.

It has also saved my back/body using a finer grind and make me look less restarted when making coffee.
I see a lot of voodoo coffee making techniques by home baristas, when I see how the pros do it, the technique is usually less fussy and more simplistic.