Here are two doses. One with an ultra chi-chi custom fit tamper and a generic 57mm.

No tapping, twirling, sucking, etc. Just mash and go.

And the pux



Not much difference, eh, Watson.

Well, it appears the one with the side cracks would have channeling. You also didn't mention which tamper did which puck.

Side cracks? Which photo?

BTW, neither shot channeled.

I believe those side cracks are just residual coffee throwing a shadow on the photo. I stopped the two tamp, tap tap to knock the loose grounds down stuff some time ago. My opinion, it does no good and can actually do harm to your puck by loosening the cohesion with the sides of the basket and passably creating small internal fissures in the puck. Now a days, I grind, dose, level, light tamp and go.

I am a firm believer that a tamp will not make up for a bad distribution of grind, but a bad tamp will ruin a good distribution and grind. my tamps look very similar to the lower photo. I use a standard 58mm Reg tamper which will leave a little residual coffee grounds on the outer edges of the puck. It does not cause a problem, but an undersized tamper; say a 53 in a 58 basket will cause a problem.

cannonfodder wrote:It does not cause a problem, but an undersized tamper; say a 53 in a 58 basket will cause a problem.

A couple years ago I spoke to one of the engineers at MACAP manning the booth at the SCAA conference. I asked him why they didn't make a 58mm piston for their auto-tamper. He claimed it didn't matter, that an even consistent tamp applied dead center with a 53mm piston for a 58mm basket would not improve if one used a 58mm piston. I didn't buy his argument, but said I'd give it a try (never did). Anyone with very good tamping skills and a 53mm tamper/58mm basket want to test his assertion?

Should I start from 57 and work down or Zero and work up

I have a 58, 53, 48 some of those plastic toys. I will give it a try when I get home if I have time; I am in Philly right now. When I have use the plastic toy which is very undersized, I always got donut extractions. I was using a heavy tamp and coarser grind at the time. If you go with a light tamp and a tight grind the results may not be as dramatic.

...I would also theorize that it depends on the espresso machine. Some have such a strong and directed flow and quick ramp up to brewing force that the coffee has no chance to settle as it would on a more 'advanced' design... re: comparing Silvia to VBM.

Thanks Randy for the reminder of the risk of generalizing. The brew pressure of the Elektra A3, for example, rises to 9 bar in less than two seconds, and yet it is a breeze to dial in the extraction (well, as long as you don't updose). The Ponte Vecchio is another noteworthy exception; as Timo reported, a near zero tamp works nicely. My guess is that you're right that espresso machines with uneven initial water dispersion benefit from firm, complete surface tamps and more headspace.