[Homeroast] Drum rotation > Jimma > PID iRoast

ricky carter rickylc99 at gmail.com
Sat Oct 9 11:30:24 CDT 2010


I completely agree with the comment about all profiles ending in 100% power,
it's the biggest hurdle for me with the behmor, P2 is an alternative, but
getting the cutback timed just right is a challenge.  a user initiated low
medium and high heat setting would make the Behmor a very nice roaster.

Of course it can be done by modding the roaster, but it would be nice if it
was built in.

On Sat, Oct 9, 2010 at 11:33 AM, Edward Bourgeois <edbourgeois at gmail.com>wrote:

> One thing that has baffled me is why all the profiles end with a 100%
> power. This goes against what the beans need after 1st crack and adds
> to the chaff singeing issue.
>
> On Sat, Oct 9, 2010 at 11:19 AM, Edward Bourgeois <edbourgeois at gmail.com>
> wrote:
> > Pro roaster design has been tweaked for many years. Much effort, r&d,
> > $$$ has gone into fin/vane design and adjusting to the proper speed
> > for the design. I'm very happy with my hybrid homebuilt but got a
> > Behmor (thank you John) early after it's release to play around with.
> > There's much to like about it. But as most 1st models it has some
> > design issues that can be improved upon. Drum speed it certainly one.
> > Agitation is very important for quality of roast along with
> > efficiency. Increasing drum speed has allowed for improvements in both
> > these areas(I'm running 50rpm but also have a 30rpm I could try and
> > compare). I still haven't had a chance to really test the chaff issue
> > Tom mentioned but in the few roasts I've done it didn't start a chaff
> > issue that was bad enough for me to notice. I've thought about trying
> > to lower the floor a bit  and redesign the chaff tray but just haven't
> > gotten around to it. For anyone who didn't see my recent mod. post you
> > can check out my blog below.
> >
> > On Thu, Sep 30, 2010 at 12:20 PM, miKe mcKoffee <mcKona at comcast.net>
> wrote:
> >> First I'll say I'm not a roaster designer or manufacturer so can't say
> >> exactly how specific drum rotation speeds are chosen for different
> roasters.
> >> Before his passing Ron did a fair amount of testing for various drums
> and
> >> drum diameters to determine how fast was too fast for his Q drums. IE at
> >> what speed would the beans not loft but instead have centrifugal force
> push
> >> them against the wall. IRC the HotTop drum rotation is ~30rpm (checked
> it
> >> but that was almost 3 years ago so memory fades), USRC 3k ~65rpm, Behmor
> >> very slow ~6rpm. Observation of other commercial drum roasters and their
> >> observed bean loft means using similar speeds to measured (counted) USRC
> >> drum speed.
> >>
> >> A common mistake is thinking the drum itself is the primary heat source
> for
> >> drum roasted beans. Modern drum roasters convection accounts for about
> 80%
> >> of the roast energy, air roasters even more. While the specific pre-heat
> of
> >> the drum and roaster IS VERY important at the beginning of the roast,
> it's
> >> importance is it's stored energy which is applied primarily via
> convection
> >> and radiation not conduction. With a bit of understanding of the types
> of
> >> heat in the roast process and observation of various roasters it becomes
> >> clear constant loft of the beans by the drum is the goal. Convection is
> the
> >> primary heat transfer in all modern roasters.  (See a good article by
> Terry
> >> Davis, originally written for Roast Magazine IIRC
> >> http://www.ambexroasters.com/information/read/heat_transfer.html )
> >>
> >> If the beans aren't vigorously tumbling convection can't occur for the
> >> majority of the beans stuck in a barely moving mass. This leaves
> conduction
> >> and radiation as the more predominant roast energies, which is the
> problem
> >> with the stock Behmor. Radiant energy primarily from the heater and
> >> pre-heated roast chamber primarily affecting the beans on the outside of
> the
> >> mass and conduction later in the roast bean to bean. At the same time I
> >> split out the heater for variac control Alchemist John put in a faster
> drum
> >> motor, with marked improved results. (We both had/have first production
> run
> >> Behmors from Joe) I never got a roast I was satisfied with just by
> directly
> >> controlling radiant heat, ie the heater. Some "ok" roasts to be sure,
> but
> >> nothing as good as Caffe Rosto profiled roasts or later CCR HotTop
> roasts.
> >> Convection or lack thereof was the apparent difference.
> >>
> >> IF a faster drum rotation causes problems with the Behmor Alchemist can
> >> chime in since fairly certain he's been using IIRC ~45rpm drum motors
> for
> >> close to 3 years.
> >>
> >> It's easy to turn beans brown, it's a lifetime Journey learning how to
> make
> >> beans sing. IMO (and that of many others) a huge part of the process is
> >> learning how to effectively control your particular roaster.
> >>
> >> Slave to the Bean  miKe mcKoffee
> >> www.CompassCoffeeRoasting.com <http://www.compasscoffeeroasting.com/>
> >> URL to Rosto mods, FrankenFormer, some recipes etc:
> >> http://www.mckoffee.com/
> >>
> >> Ultimately the quest for Koffee Nirvana is a solitary path. To know I
> must
> >> first not know. And in knowing know I know not. Each Personal
> enlightenment
> >> found exploring the many divergent foot steps of Those who have gone
> before.
> >>
> >> Sweet Maria's List - Searchable Archives
> >> http://themeyers.org/HomeRoast/
> >>
> >>
> >>> -----Original Message-----
> >>> From: homeroast-bounces at lists.sweetmariascoffee.com
> >>> [mailto:homeroast-bounces at lists.sweetmariascoffee.com] On
> >>> Behalf Of Jim Couch
> >>> Sent: Thursday, September 30, 2010 7:49 AM
> >>>
> >>> Believe I saw some comments from Tom cautioning about the "dangers" of
> >>> spinning a Behmor drum too fast, something about it causing
> >>> chaff collection
> >>> problems and messing with the ability of the beans to
> >>> transfer heat to each
> >>> other perhaps problems would be a better word than dangers..........
> >>>
> >>> On Thu, Sep 30, 2010 at 8:36 AM, Robert Yoder
> >>> <robotyonder at hotmail.com>wrote:
> >>>
> >>> >
> >>> > Hi MiKe,
> >>> >
> >>> >
> >>> > Thanks for your posts!  So much to learn!
> >>> >
> >>> > >
> >>> >   Even directly controlling the heater via variac
> >>> > > didn't help enough because drum rotation was so slow yielding poor
> >>> > > convection. If I hadn't acquired a CCR HotTop so soon
> >>> after the Behmor
> >>> > > likely would have mod'd it further with faster drum and bean temp
> >>> > probemaking it a decent roaster.
> >>> >
> >>> >
> >>> >
> >>> > Can you clarify the drum-rotation/poor convection comment?
> >>> Is there a
> >>> > typical shop-roaster drum-rotation speed?  How is that chosen?
> >>> >
> >>> > Happy Roasting,
> >>> >
> >>> > robert yoder
> >>
> >>
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> >
> >
> >
> > --
> > Ed Bourgeois aka farmroast
> > Amherst MA.
> > http://coffee-roasting.blogspot.com/
> >
>
>
>
> --
> Ed Bourgeois aka farmroast
> Amherst MA.
> http://coffee-roasting.blogspot.com/
>
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