[Homeroast] Turning Bottomless Portafilter

Joseph Robertson theotherjo at gmail.com
Wed Aug 25 19:06:08 CDT 2010


Right on RayO. Bottomless is a great tamper teacher and then some.
JR

On Wed, Aug 25, 2010 at 2:33 PM, <raymanowen at gmail.com> wrote:

> "You never know when a jet might strike..."
>
> I had 'em all over the place (3 or 4 at least) after I converted the
> Crapesso by removing the three plastic flow-restriction discs from the
> bottom of its portafilter handle. Pre- castration, there were four surfaces
> facing each other that were inaccessible for cleaning- not a good
> situation.
> Even my Simple Green/ Dishwasher detergent Witches Brew didn't clean it
>
> The flow restriction would create back pressure with any grind and packing,
> hence the plastic "tamper." Got a better one- 52.9mm tamper for the 53.3mm
> filter basket or about 0.017" clearance. The Idiot Savant that designed the
> machine had the theory that one is not bothered by things he cannot see.
> (Or
> so said Marketing)
>
> The "coffee jets" are a good indication that the packing and tamping are
> uneven, otherwise, why would any filter perforation have more pressure and
> flow than others ? In ideal espresso brewing, the packing is homogeneous
> and
> the flow resistance generates the 9 bar back pressure. That pressure only
> exists at the very top of the puck, and diminishes to Zero at the bottom,
> for a melange brew. That's the way everyone likes it, so...
>
> The flow restriction/ pressure regulation south of the puck is probably a
> good idea, with a larger diameter pf = less pressure variation through the
> puck. If the puck were just 1 grain deep, there would be no pressure drop
> when the water passed the coffee field.
>
> Which would be harder to cross,  an acre of corn in a 209' square field or
> a
> mile long field, just crossing the narrow 8ft 3inch strip?
>
> My demi just fits over the open bottom of the pf handle, so I just watch
> the
> show through the glass. No apron needed. Different-sized porta filters
> should brew and extract differently.
>
> The fact that a few perforations spray out while the rest just flow is the
> first step in  trouble shooting.  Don't ignore it- solve it and your
> espresso just gets better. + Roasting, + Grinding.
>
> Cheers, Mabuhay -RayO, aka Opa!
> --
> Persist in old ways; expect different results - suborn Insanity...
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