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Base Knock-Convex

Our Tamper Knock-Convex bases

JoeFrex knows which espresso accessories a barista wants!

All bottom parts KNOCK-CONVEX have a slightly outward curved surface for pressing the espresso and are made of solid stainless steel: 1.4305 on a CNC lathe. Similar to the American Curve, the difference between the center and the outer edge is 1.5mm.


> Why the term Knock? 

> Why Convex?  

Base Knock-Convex
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JoeFrex - 55 mm Tamper KNOCK-CONVEX Reviews with
JoeFrex - 55 mm Tamper KNOCK-CONVEX

2-4 Workdays Article No. 9052-55-bkc

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JoeFrex - 57 mm Tamper  KNOCK-CONVEX Reviews with
JoeFrex - 57 mm Tamper KNOCK-CONVEX

2-4 Workdays Article No. 9052-57-bkc

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JoeFrex - 53mm Tamper KNOCK-CONVEX Reviews with
JoeFrex - 53mm Tamper KNOCK-CONVEX

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JoeFrex - 58 mm Tamper KNOCK-CONVEX Reviews with
JoeFrex - 58 mm Tamper KNOCK-CONVEX

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Why the name Knock?

After the first ramping of the espresso, a light knock is applied to the side of the portafilter, which causes all the espresso powder to fall from the side into the portafilter. Then it is tamped again. To avoid having to use the tamper base for this light knock on the portafilter, which could damage the soft portafilter, or even the wooden handle, the tamper can now be knocked with the silicone ring incorporated in the base. We have legally protected this invention.

Why Convex?

Normally, the surface of the espresso tamped in the portafilter does not matter much; whether Flat (flat) or Convex (convex), there is enough space between the espresso surface and the shower screen so that the water can spread evenly over the espresso and the espresso powder also penetrates evenly. However, if flat sieves are used or significantly more than 7g (1-cup sieve) or 14g (2-cup sieve) are used, there may be too little space between the espresso powder and the shower sieve for optimal brewing water distribution. For this purpose, a Convex tamper base can be used, which leaves a trough in the center for better water distribution.