To add my 2cents (well after reading my comment maybe it's worth 1cent):

I have fallen to the trap of buying a larger diameter tamper from RB (2 actually as I wanted to try the C Ripple and the American Curve) of 58.4mm. I came to this measurement after measuring the 8 different baskets that I have of various styles (synesso straight, marzocco ridged, generic 58's, those that came with my Izzo and a couple of the 'micro fine holes' baskets) doubles and triples. To me, almost all the baskets at the outward ridge measured closer to 59mm+ then 58mm (except for the marzocco which is a 57mm basket but at the ridge was closer to 58.4), and it wasn't until slightly more than halfway down did the 58mm baskets actually measure 58mm.

Considering that I liked to updose my shots and pull anywhere between 16g-21g shots depending on the coffee, I concluded that given the baskets and given the tamper size I would be prone to less "mess" on the sides. Which I am.

However, I too have also devolved my tamping procedure somewhat and "gasp" even fail to weigh my shots some mornings (with the kids getting you up at 0500 sometimes I can't be bothered and just appreciate that my timer works and the machine is warmed up for me) but have a rough idea with each basket how much should be in there.

I can't claim that a bigger tamper helps, but it's all voodoo anyways and for me it just feels better.

I just got in the mail from Orphan Espresso one of their Dosing Funnels and I am as happy as a clam now as I give my PF a thump for a nice settle, and then a straight tamp and off I go. My shots are clean and tiger striped and rarely do i get the dreaded donut extraction.

I was having the same problems with channeling on an Alex Duetto, and I actually wondered the same thing about the tamper size.

The one thing I changed that seemed to work for me was to stop dosing directly from the grinder into the portafilter. After doing a lot of reading on some old threads I found some rather convincing discussions on the underrated importance of distribution. When I dosed directly from the grinder (a Vario) to the portafilter I was getting a mound of coffee with moderate clumping. Now I grind into a small cup and then pour it into the portafilter. This way I can control the distribution. Then I either sweep my finger over the edge to clean up, or push the grounds around to even out the top (depending on the dose), straight tamp and I'm done.

This is more work than I previously through necessary, but so far it seems to be working quite dependably.

The attention to distribution of grinds into the portafilter has greatly improved my shot quality, both taste and aesthetic.

My experience mirrors Brians (lolgun). I switched to the 58+ Torr tamper about a year ago and stopped using the straight 58mm sized tampers. The 58.4mm RB base fits the Synesso baskets perfectly with just enough space to nutate if it's your style. Seldom are there grinds stuck to the inside walls of the basket. I don't know if the size has anything to do with the elimination of channeling but since switching to the larger size I wouldn't go back to the smaller size. It just works for me.

Bob

Thanks lolgun and Nik, I wanted to hear from someone who has used an oversize tamper. Eventually I may spring for an oversize RB tamper but for now it sounds like I just need more practice with dose and distribution.