HomeRoast Digest

Topic: Modded Pumper loft weight: Was Poppery II Air Popper (7 msgs / 167 lines)
1) From: Douglas Strait
This is a multi-part message in MIME format.
At a line voltage of 124VAC I can loft up to 270g. I've modded several =
Wear-ever #72000s this way and they vary through a range of about 20g. =
By comparison, a poppery P1 I did this on would max at 280g. These =
weights are with the poppers level.  I could gain another 10-20g by =
I fullwave rectify the incoming AC, filter it, and then Pulse Width =
Modulate [PWM] it to control fan speed. This is the same circuit that =
was discussed on the list back in January. I sent you the relevant =
schematic via email on Jan 26 of this year. BTW, If you decide to =
implement this, I have since found a better part than the one I had =
suggested for the filter capacitor, C1 on the fan control. It has a =
higher ripple current rating. 

2) From: Scott Marquardt
Oh, my aching head. I'm so confused! I don't have time to pull up the
schematic just now (still have it though), but I didn't recall that you were
DC'ing the fan. It takes DC? Good grief, I don't even remember -- are there
some diodes on the back end of that motor? I'd thought it was an AC! Geez,
I'm REALLY out of it.    ;-)
I run line into a 140 boost Variac (a low wattage unit I've had for 20
years) for the blower, and let the heater run through a short extension cord
to cool it just a bit. With a Corning 3" bread tube and generous tilt, I'm
able to "flow" (I won't call it "loft" per se) a superb circulation of 10
oz. (sometimes more) if the beans are small, 8 oz. for typical dense beans.
Monsooned Malabar is insanely light; in theory I could do more than 8
easily, but in practice the flow is darned weird when I go much taller.
There's a proportion of tube width to height that makes a definite
difference. Also, when I say "small" beans, I do NOT mean peaberry; the form
of a peaberry bean presents serious challenges to the way this is working
for me. The hemisphere morphology of a typical bean makes for far better
agitation of a  bean mass, IMO. I have to do smaller batches of peaberry
than of normally shaped beans of the same size.
On Wednesday nights I do six to eight 8-ounce batches in the Pumper.
The operational profile consists of preheating to 350 or so with the fan on
full (boost to 140), charging the column with 8 ounces, and waiting till the
bean mass is at 350 before lowering the Variac boost. Depending on ambient
air temperature, just how and when I do this varies. It also depends on
whether I'm doing a light roast or a dark roast. In any case, I shoot for 12
to 16 minutes.
I also use a Salamander IR emitter alongside the tube, which has an
interesting way of "autopiloting" the last few minutes of roast, once the
beans have expanded enough that the mass is high enough in the tube to
absorb the heat well. The effect is to smooth out any adjustments I make to
the blower during the last few minutes of the roast. I haven't thought of
that as the system "being less responsive" so much as the system "being less
vulnerable to my random idiocies with that Variac knob."    ;-)
I also have my "flow impeder" in play, which takes a lot of pressure off the
beans that are below the tube, down where the action is. I suspect that's
very much responsible for the amount of beans I can do. Also, it helps me
when I haven't weighed a batch and I'm just "winging it," because as I pour
beans into the tube the point at which they begin to fail to circulate well
is more of a range than a point; they don't just STOP. Operationally, when
doing this I always leave the boost at about 135 just as a safety; when the
flow slows I stop charging and boost back up to 140.
What kind of "loft" are you after? A "spouting up the center" kind of thing?
I'd think not, if you're tilting.
- Scott
On 10/2/06, Douglas Strait  wrote:

3) From: Douglas Strait
In the stock Pumper the fan is operated on AC.  The nameplate says 
120AC. The motor is, in fact, a series wound commutated [also known as 
''Universal''] motor which is happy with DC. In fact, this type of 
motor is more properly thought of as a DC motor that is also capable 
of running on AC. Historical note: almost all motor driven consumer 
appliances sold in the early part of the 20th century had AC/DC 
universal motors. This is because prior to widespread rural 
electrification many folks were powering their homes from 120V worth 
of lead-acid batteries. Here in the South, you still occasionally hear 
old-timers refer to the little structures that housed these batteries 
as the ''Delco house [or shack]'' after one of the dominate 
manufacturers of lead-acid batteries in that era.
It sounds like you setup does about as well as mine.
I generally don't run batches big enough to require tilting. Spouting 
up the center seems to occur only with very small batch sizes. For 
more normal batch sizes beans rise to the top of the bean mass in some 
areas and are subducted elsewhere on the surface of the bean mass.

4) From: Brett Mason
hit it with a hammer and buy a skillet....
On 10/2/06, Scott Marquardt  wrote:

5) From: Scott Marquardt
My head?
On 10/2/06, Brett Mason  wrote:

6) From: Brett Mason
no - all those fangled wires and such...
On 10/2/06, Scott Marquardt  wrote:

7) From: Scott Marquardt
Just wanted to be sure. The advice is probably sound either way.    ;-)
On 10/2/06, Brett Mason  wrote:

HomeRoast Digest