Bunnzilla: calibration issue - Page 3

Grinders are one of the keys to exceptional espresso. Discuss them here.
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#21: Post by JohnB. »

Looking at your photo of your face plate it looks like the bearing/adjustment screw end sits flush with the face plate recess area?? On mine the entire body of the bearing is out beyond that recess face.

mtbizzle (original poster)

#22: Post by mtbizzle (original poster) » replying to JohnB. »

Thanks John. Do you mean the grind adjustment screw, in this photo? userpix/41652_pxl_20210322_044939027_hb5940LU.jpg In that photo, the grind adjustment screw was unscrewed/loosened as much as possible. The black dial would move closer to the dial plate as I tightened it. I'm not sure if that's what you mean, we may be talking past each other.

About moving the motor assembly backwards. Another user suggested that the outer burr carrier may be grinding the back of the face plate. I did find metal shavings and perhaps scratches on both parts, so they may be right. Moving the motor assembly backwards, I was thinking, might be a way to add more space between the parts to prevent that contact.

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mtbizzle (original poster)

#23: Post by mtbizzle (original poster) »

leftiesrule wrote:I remember having a similar problem after making my Mini-Bunnzilla... There was metal fines in the grind chamber too. I came to the conclusion that the calibration screw was so far out that the burr carrier was wobbling in place and either jamming or dragging on the grind chamber. My problems went away after tightening that calibration screw...
I tried calibrating/zeroing, starting by adjusting the calibration screw so it was about 90* off of touching, trying to follow what you did. The faceplate was tightened evenly until there was no screw movement with light force.
Calibration seemed to be working, but then the grinder went haywire again, grinding itself and sending metal dust flying -- video here


You can hear a change when the "grinding" starts, when metal dust started to fly. It does not seem like burr churping, and it didn't stop after I loosened the burrs.

Metal dust - lots in screw holes on outer side of the outer burr carrier, seems it is the carrier grinding the grind plate. Shouldn't the calibration screw pressing against the burr rotor cup on the outer burr carrier prevent that??


#24: Post by jayo »

What direction are you turning the grind adjustment screw in your most recent video?

mtbizzle (original poster)

#25: Post by mtbizzle (original poster) » replying to jayo »

Clockwise (tighter). The calibration screw was about 90* until contact/locking of the screw when I turned off the machine.

First photo is as tight as screw will go without force

Second photo is where I stopped the video

mtbizzle (original poster)

#26: Post by mtbizzle (original poster) »

Request to anyone with a Bunn G series -- could you take out the auger spring (#3) and measure it for me?