[Homeroast] Turning Bottomless Portafilter

Joseph Robertson theotherjo at gmail.com
Sat Aug 28 11:07:57 CDT 2010


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.
>> > _______________________________________________
>> > Homeroast mailing list
>> > Homeroast at host.sweetmariascoffee.com
>> >
>> http://host.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.com
>> > Homeroast community pictures -upload yours!) :
>> http://www.sweetmariascoffee.com/gallery/main.php?g2_itemId=7820
>>
>>
>> _______________________________________________
>> Homeroast mailing list
>> Homeroast at host.sweetmariascoffee.com
>>
>> http://host.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.com
>> Homeroast community pictures -upload yours!) :
>> http://www.sweetmariascoffee.com/gallery/main.php?g2_itemId=7820
>>
>
>
>
> --
> Ambassador for Specialty Coffee and palate reform.
>



-- 
Ambassador for Specialty Coffee and palate reform.


More information about the Homeroast mailing list