Although I feel that tamping technique is very important, it is all for naught if distribution is poor. For the past year or so, I have been focusing a lot of attention on distribution techniques. I feel that this is one of the most overlooked areas of shot prep. Since moving over to triple baskets the need for proper distribution has become even more important. I have also found that different types of group heads require different methods of distribution.

Once you have achieved proper distribution technique for your machine and basket size, various tamping techniques can be experimented with to help achieve the best extraction. Tamping almost becomes a type of "fine tuning". It can actually be alot of fun to see how minor changes in tamp style can affect the shot.

I always remind people that the 30 or so pounds of pressure that are applied during tamp are only a fraction of the force (9bar) that the puck will encounter during extraction. Tamping only helps the puck to receive this force evenly.

The specifics of tamp technique only come into play once you are sure that grind and distribution are in order.

Abe Carmeli wrote: I've stopped tamping into the P/F. Not because of problems with the Macap, but because I do not see any advantage doing it in a home environment.

When this technique was brought up on the Brewtus group, we tried it but didn't like it because it was a pain to knock out the puck (the basket comes too).

But, as Chris has discussed, it's important to rotate the portafilter when dosing. We have a Mazzer Mini-E (no doser, just a funnel), and I find that if I just let it fill the portafilter straight that I get blonding early on the back half -- and if it's a triple basket, channeling too.

I've mostly stuck to doubles, since even rotating the portafilter doesn't quite do it since I can't rotate it 360.

But, combining these two bits of advice, I tried filling the basket out of the portafilter again, this time constantly spinning it. And, also using advice from Chris, tapping the basket on the forks to settle the grounds -- and this I did periodically a couple times during the fill. Wonder of wonders, the back-half blonding was completely eliminated. And even with the triple basket. And no channeling.

Thanks muchly! Alas, my partner-in-espresso doesn't like leaving the spring out, so I'll either have to convince him of the advantage or get another naked portafilter. Heh.

Michelle

When this technique was brought up on the Brewtus group, we tried it but didn't like it because it was a pain to knock out the puck (the basket comes too).

Michelle,

Get a ridgeless basket, and you can leave the spring in.

I got a gently convex (US curve) tamper friday from Reg Barber and things are much better for me. Adjusting the grind is suddenly a pressing matter, cause the pours are generally centered (in the bottomless) and steady.

The nutating motion is mentioned as something for flat tampers:

Stronger baristas may use heavier tamps, while some use a nutating motion (rolling the tamper in a motion like a flipped coin settling) to accentuate the pressure towards the edges of the basket. An alternative to the nutating motion is using a convexly curved tamper, which accomplishes the same thing.

The nutating roll seems natural with the convex, the roll will be over a wider area (like the rings on Saturn) than with the flat , and not so acute against the very side; the convex is not very well suited for NSWE side-scraping tamping, and nutation seems like it might work very nicely after tapping; it feels even and natural. I'm glad I got the short handle without the ball end, the low control feels good.

I've got to say again, in keeping with malachi's counsel on s/n ratio, that I'm just talking, and know really nothing.

Edit: A flat tamper can't hit precisely on the edge with a nutating motion because the slope from the rim of the PF, along the side of the tamper base, to the point where it creates a circle on the coffee near the side, can not be on the side; there's an offset like (diameter of circle of max nutating pressure) = (.97 * PF diameter) or something like that.

A concavity would put the direct perpendicular pressure right at the edge of the tamper at the time of the main tamp, so a perfect-fit concave tamper would create a pressure circle right against the sides of the PF.

Nutating with a flat would seem to promote scraping across the surface as the tamper tried to snug up into the pf circum.

I understand that the tamp has a modest responsibility, but the view inside of a PF is exercising my brain.