Astoria/RIO/Brasilia Factory Cut Bottomless Portafilter
This bottomless portafilter will fit some, but not all models of Astoria, RIO & Brasilia espresso machine group heads. The standard bottomless or naked portafilter features a clean precision cut and chrome job where the bottom and spout once resided. It measures 79.5mm across at the widest point (the "ears") on the top. The ears measure 6mm tall at the thickest point. The opening on the bottom measures 62mm inside diameter. Includes a 21 gram basket, suitable for 58 mm and smaller tamper bases.
Using this portafilter the barista can watch the coffee brew right from the bottom of the filter basket and know immediately if channeling occurs, signaling the user that a level tamp was not made which makes this an invaluable tool for training.
This is an item that created quite a stir in the specialty coffee industry, crossing over to espresso hobby and enthusiasts as well. The bottomless portafilter has been referred to as "naked", but what ever you call it, it is truly a revelation. Another innovation Espresso Parts brought it to the market first, originally modifying our own with just exposed brass on the bottom and no chrome.
For an excellent guide on trouble shooting or "Perfecting the Naked Portafilter Extraction" read the article of the same title on Home-Barista.com.
Caution: This portafilter has been produced by a machine parts manufacturer, machine milled to get the cleanest, smoothest surface possible. Please note that the inside is chromed all the way through and the bottom edge is very precise and can be relatively sharp.