[Homeroast] Turning Bottomless Portafilter

Joseph Robertson theotherjo at gmail.com
Sat Aug 28 11:09:17 CDT 2010


This nakid pf thing has just got way out of hand...will someone post a video
clip so we can get back to baking some beans....;^))))
JR

On Sat, Aug 28, 2010 at 9:07 AM, Joseph Robertson <theotherjo at gmail.com>wrote:

> Now a cup of joe that's another thing all together.
> JR
>
>
> On Sat, Aug 28, 2010 at 9:07 AM, Joseph Robertson <theotherjo at gmail.com>wrote:
>
>> I believe it's been done. Again a vice might be nice and I don't mean a
>> cigarette while using the grinder....my bad. ;^)
>>
>> On Sat, Aug 28, 2010 at 8:38 AM, dennis true <dennist3 at gmail.com> wrote:
>>
>>> what about just using a bench grinder.......hehehehhee
>>>
>>>
>>> On Aug 28, 2010, at 2:58 AM, raymanowen at gmail.com wrote:
>>>
>>> >   1. "...use a hand drill / Vise to hold it and a hole saw to cut mine
>>> >   out.
>>> >   2. From now on I will do my own.
>>> >                             [When you see something done by someone
>>> >   experienced in doing it, the process always looks easy. Something
>>> looks
>>> >   simple like changing the engine or automatic transmission oil and
>>> filter
>>> >   when someone else does it-  or a flat tire? Looks easy when you see
>>> it done.
>>> >    Show of hands- How many people actually do their own maintenance on
>>> a
>>> >   regular basis?]
>>> >   3. The chrome coating is real thin. the core is bronze I think.
>>> [Bronze-
>>> >   like the Temple bells in Thailand? Stupid Marketing always says
>>> "Heavy
>>> >   brass" or "Marine grade brass"] Their specific heat is lower than
>>> that of
>>> >   the water they don't touch...
>>> >   4. Very easy to cut with a hole saw."
>>> >
>>> > Maybe Not-
>>> > Did you see the machinist using a Hole Saw or claw hammer?  He did Not.
>>> > In order to do the machine work with precision, conserve tools and the
>>> porta
>>> > filter handle itself, the cutting tools and workpiece were firmly
>>> mounted on
>>> > the lathe.
>>> >
>>> > If your friend did not fracture the porta filter handle between the two
>>> jaws
>>> > of the bench vise; did not break the pilot hole drill bit when the hole
>>> > saw seized in the work piece, crack his wrist, yank the pf out of the
>>> vise
>>> > as it broke and busted the drill motor when it hit the floor, he's
>>> either a
>>> > Magician or extremely lucky.
>>> >
>>> > Luck and Magic may be entertaining, but have no place in a machine shop
>>> or
>>> > on the highway. (When you feel inclined to buzz it over 100, are all
>>> the lug
>>> > nuts torqued, tire pressures and engine oil just right? Do you Know so
>>> or
>>> > just Hope so?)
>>> >
>>> > Cutting out the entire bottom of a portafilter might seem easy with a
>>> large
>>> > hole saw, bench vise and hand drill, but it's not the all-pro move. It
>>> will
>>> > probably cost you some painful surgery, a hole saw, a hand drill, a
>>> porta
>>> > filter and some CSA points.
>>> >
>>> > At Colo School of Mines Earth Mechanics Research Institute, I used a
>>> 500-ton
>>> > press and 12,000 psi triaxial pressure to test and chart record the
>>> failure
>>> > point of 2" OD X 4"L oil shale cores, up to 480° C, (Love PID
>>> controller,
>>> > type K s/s sheathed grounded junction thermocouples) and my strain gage
>>> load
>>> > cell.
>>> >
>>> > According to an ME/ Chem E friend, "Some of the stronger bronzes need
>>> full
>>> > hydrodynamic (pressure) lubrication, or they gall and seize. (That's
>>> what
>>> > grabs and breaks the hole saw, your wrist, and yanks the pf out of the
>>> vise
>>> > if you had a good grip on the drill)
>>> >
>>> > The heavily leaded bronzes survive much better when lubrication is
>>> marginal,
>>> > if speeds are Slow Enough. Ever seen a slow hand drill? Hammer
>>> Mechanics
>>> > usually run full-speed.
>>> >
>>> > The opposing material and finish can make a big difference in the wear
>>> rate
>>> > and tendency to seize and gall. (Break your wrist)
>>> >
>>> > Poor geometry usually can not be compensated for with "better" as-cast
>>> or
>>> > annealed materials." The tabs of 58mm pf handles each have to withstand
>>> > almost 300 pounds in shear at 9 bar pressure. Things could go rong in a
>>> > hurry if the shot stalls and the OPV doesn't bypass and relieve the
>>> pump
>>> > pressure, like my former Crapesso.
>>> >
>>> > Don't even think of using type J thermocouples around moisture- the
>>> couple
>>> > is Iron/ Constantan. Guess which one corrodes like Hell and destroys
>>> the
>>> > junction?  Type K couple is Chrome-Nickel/ Aluminum-Nickel or Chromel/
>>> > Alumel.(Was © Omega) The Chromel is a laboratory-grade Nichrome- the
>>> heater
>>> > wire in toasters- and can withstand ≤ 3000° F.  Alumel is a little
>>> lower and
>>> > type K is a stable Seebeck couple at 2700° F.
>>> >
>>> > Cheers, Mabuhay -RayO, aka Opa!
>>> >
>>> > Do what you always did, get what you always got- If you get back
>>> without an
>>> > ambulance ride or tow truck, maintenance was OK.
>>> > _______________________________________________
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>>
>>
>>
>> --
>> Ambassador for Specialty Coffee and palate reform.
>>
>
>
>
> --
> Ambassador for Specialty Coffee and palate reform.
>



-- 
Ambassador for Specialty Coffee and palate reform.


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