I posted this question as a curiosity but now I see where flat bottomed tampers would be superior to convex tampers when using a completely flat basket. In a perfect world, your puck would have exactly the same amount of grounds in every section and each section would be the same thickness. Therefore, if you are using a convex tamper with a flat basket, the middle would be either thiner (meaning less coffee) or more compressed. That would lead to either overextracted (less coffee) or underextracted (denser) middle section of the puck. In my mind, I would imagine the attraction of the convex tamper came because after years of use, baskets would become convex too and the convex tamper would maintain an even distribution and tamp.

All very interesting stuff!!

I would imagine the attraction of the convex tamper came because after years of use, baskets would become convex too

Or it could be because the baskets flex slightly convex during extraction.

Try this :

Dose [normal, not uber] an easily pulled coffee into basket, distribute with finger, gentle vertical rap or two, lock, pull.

Do this for what ever interval satisfies and discover just how little tamping contributes.

cafeIKE wrote:Try this :

Dose [normal, not uber] an easily pulled coffee into basket, distribute with finger, gentle vertical rap or two, lock, pull.

Do this for what ever interval satisfies and discover just how little tamping contributes.

This works if you do a good job with distribution. As John said, the tamper can serve as a distribution tool to compensate for inadequate distribution by other means. A tamper is handy for low doses that don't come up the PF rim and thus can't be distributed easily with a finger.