Empty Chaff Collector

My last two roasts have had a new issue where chaff isn’t going into my collector. I don’t have any error codes to indicate my fan is not working properly so I’m not sure what changed. I thought maybe I failed to seal the chaff collector when it first happened but I double checked everything the second time and I don’t see an issue. I decided to do a deep clean on the metal mesh filter and the metal fan just in case but I never had this issue before and the mesh filter didn’t seem all that bad. Any ideas? I’m starting to worry that I’m damaging the roaster with each use.

Just a shot in the dark-

With the chaff collector off, remove the rubber stopper from the bean chute and look from the rear toward the front. You should be able to see the bean chute clearly if you illuminate the chute with a flashlight shining down. Anything in the tube will be outlined in silhouette. If you can’t see the other end clearly it’s likely the transfer tube (the rectangular tube which runs from the bean chute area to the rectangular opening at the chaff collector) is at least partially blocked with beans, chaff, “junk”. A strong vacuum ought to clear it but dragging something thru the tube always does the job.

What made me think of this is your most recent roast where I see fan speeds as high as F8. The oddity of a centrifugal fan like the exhaust fan is that if flow rate goes to zero, the load on the fan also goes to zero. So a blocked transfer tube will have the exhaust fan spinning with essentially no load on it- and little or no air moving out of the exhaust port.


Another thing that you might try after checking for a blocked transfer tube per Bruce’s excellent recommendation: is to cycle through the PRS button until you are in Roast mode. At that point you can turn the power down to 0 and then try different fan speeds by changing the F up or down and feeling for air flow over the back exhaust.
With the power P at Zero (No Heat), you could even take the chaff collector off and look at the fan and see if it is spinning with out worrying about damaging the Bullet.

Hopefully it is just a blocked transfer tube.

Cleaning the exhaust tube makes logical sense but I did a quick visual and while it isn’t clean it hardly appears to be blocked. I cleaned the stainless steel filter and the fan and will try clean the tube next.

It really does seem like the fan is not operating even though I visually confirmed it was working. Maybe I’m being dumb but isn’t the exhause fan impeller what causes the chaff to be sucked through the tube? Because the impeller seems to be working fine yet evidence says it’s not pulling air at all. I forgot to mention that I see tons more chaff falling out the front and even saw some smoke making it’s way out the top rubber plug where beans are dropped.

One thing I failed to mention is when this first happened was after I updated the firmware by mistake. I am either on 605 or the beta, I can’t tell which. But perhaps that was coincidence.

I will tackle the tube next and see how clean I can get it. Fingers crossed.

Yes the little squirrel cage fan is what causes the chaff to be sucked through the tube.

How did you confirm the fan was working? Did you see it turning when looking down the exhaust vent?

Could you feel the air coming out of the exhaust?

The smoke coming out of the top rubber plug makes me wonder if something changed that is causing the fan to rotate backwards.

Another idea:
Have you calibrated your fan? That might help if it isn’t ramping up to the correct speed.
In fact, I think that I would do that first. They are probably controlling the fan with PWM. Pulse width modulation. It is possible to reverse a DC motor with PWM although it is not a common way to do it.
The firmware update may be the culprit.

It doesn’t hurt to calibrate the fan. There is no down side and it eliminates a possible fault.

From the manual:
To calibrate, please follow these steps:

  1. Take off your chaff collector (note: NOT just the chaff filter)
  2. Turn on the Bullet and go to the menu section 6 by clicking F1 until the clock LED shows 6.
  3. Press the “A” button (top left button) If no calibration has been done before this should start the process.
  4. Start the calibration process by clicking both fan Up(+) and Down(-) buttons at the same time.
    Now the calibration starts and this can take about 5 minutes to complete. When it is finished the Bullet will beep for two seconds and flash P8D.
  5. After the calibration, you can toggle between un-calibrated or calibrated fan speeds by clicking the “A” button in menu 6. 3 dashes - - - is un-calibrated and P-d means calibrated.

And is the squirrel cage impeller securely attached to its shaft? Maybe the motor is turning but the squirrel cage is not.


Or the squirrel cage is set flushed to the back and won’t spin freely. It needs a tiny bit of gap before fully tightening that screw. EDIT: but not so much gap that it rubs against the rubber gasket of the chaff collector which would also prevent it from spinning freely.

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I think I’ve fixed the issue. I’m not sure what the exact problem was but I cleaned the filter, fan, chute, and calibrated the fan. Ran a test batch with old seasoning beans and it seems to be working.