Like others I employ a simple consistent tamp before pulling the shot and in my opinion everything else is show. About the only thing I do worry about is grounds on the rim of the basket (where it contacts the head gasket) but a quick sweep with a finger and its right into the group for me.

HB wrote: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?

Seems like a worthwhile test. I don't have a 53mm tamper, so I used my 51mm Gaggia Factory tamper. Dunno about the quality of my tamping skills. I gave one firm level tamp with no tapping or polishing, and brushed off extra grinds with my finger before taking pix and pulling the shots.

Although I've long been an advocate for deemphasizing the importance of tamping, I expected to see some shot degradation with the smaller piston (most likely a donut extraction).


51mm piston above, 58mm below

As luck would have it, the pictures actually captured a prettier pour from the 51mm piston. That pour was a bit too fast, on the lungo side (perhaps should have expected that). But no spritzies, donuts, or other evidence of an uneven extraction.

Granted, my Vetrano is a highly forgiving E61 machine. But I believe Ian's got it right. Grind, dose and distribution are far more important than tamp for great espresso.

Randy G. wrote:...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.

I cut my home espresso teeth on a Solis SL-90*, a class similar to Silvia and a PeDe hand grinder. The Solis comes with a built in tamper next to the group. A 'heavy' tamp will lift the under 20# machine. My first tamper was double ended [pot metal?] thingy that had one end too large and one end too small for the ??mm basket that I happened to espy in a kitchen shop. About the only difference between the built in and the too small end was ease of cleaning. Years later, I turned the too big end to a perfect fit after learning about tapping & twirling.
The reason I quit lurking on H-B was to participate in the Tamper Road Show :

cafeIKE wrote:Bottom Line:
My complete unfamiliarity with convex tampers, which probably require a complete rethink on GDT, prevented me getting a good shot with the Radical Pro. Perhaps the profile is poor match to the VBM. Other than that, I'm certain a few days use of any of the tampers which feel comfortable in the hand would yield a consistent pull. I'm confident that if I'd started with any one of them, I'd be perfectly happy. I do like the feel of the snug basket fit of the Pullman, so perhaps I'll wrap a layer or two of duct tape around my tamper. Recommendations on best color tape for espresso greatly appreciated.

* Never used the pressurized baskets, not once.

I did try exactly that: wrapping tape around my tamper.

The result was an air-tight fit, very nice to tamp with, but with a BIG downside: when removing the tamper from the basket, it would lift the coffee and ruin the tamp because of the vacuum created by the tamper. At first I couldn't figure out why the perfect fit seemed to ruin my shots, but I found the cause by turning over the portafilter: the coffee fell out right away.

by Gabelstaplerfahrer on Mon Oct 13, 2008 8:05 am

I did try exactly that: wrapping tape around my tamper.

The result was an air-tight fit, very nice to tamp with, but with a BIG downside: when removing the tamper from the basket, it would lift the coffee and ruin the tamp because of the vacuum created by the tamper.

I got the same problem, when I decided to upsize my piston. Before ordering, I wrapped foil-backed gift tape around my 57/53mm double-ender. With a caliper, I found that 59mm jambed into the basket taper, for a 15g dose. 58.5mm gave a snug fit, but lifted the coffee pack, on piston removal.

58mm was ideal, giving a small gap for air escape. I suspect this suction problem is more prevalent with dark roasts (I take mine to rolling 2C), so the grinds are a bit oily. It may not be an issue with medium roasts, where the grinds (perhaps) breathe more.

I had this problem with very dry, hard to tamp coffee. Strangely enough it wasn't old, but a very fresh, light roast. I really felt like "I've cracked it, this is a great tamp!" and... it was ruined.

Maybe a snug fit isn't a problem or it might even be desirable, but the tamper should get a little dimple on the side to let air through. Or an air channel in the middle, something weird like that would be cool to explain to fellow coffee enthusiasts