Hi everyone,

I am in the middle of a Bunnzilla conversion- installing Ditting 804 burrs in a mid 90's Bunn G3. The grinder functioned well when tested at the seller's shop. There was just the obvious sign of extremely dull burrs (imagine the most inconsistent particle size distribution).

After tear down I confirmed the burrs were original (stamped '94 & '95). Jobs completed are the bag switch removal, deep cleaning inside & out and new trifecta detent plate / sticker from combination.

Mill City Roasters supplied the Ditting burrs with conversion ring. Here is my problem... After installing the new burrs and reassembling, something in the grinding chamber makes a horrible screeching sound. There is no previous post that lists this problem but I am hoping someone can help either through experience or the community can help steer me through the troubleshooting.

Symptoms: 1) A horrible screeching sound and visible metal powder coming out the chute. It is not the burrs touching. I know this based on previous experience calibrating a Vario that burrs touching is more of a higher pitched whining sound. Also, because there is no sign of wear on the burrs and the adjustment dial is backed way off.

Things I have ruled out: 1) The motor because it runs quiet before reassembling the auger and everything else. 2) I have unassembled, confirmed everything is tight & reassembled three times. After one reassembly the grinder ran quiet for a few seconds, then I switched off, then on and the problem returned. My conclusion here is that the new parts are to spec and I am missing some nuance in the assembly.

Things I have not ruled out: 1) The auger spins free before I install the front plate but this is before the front plate pressure puts everything in compression.

Things I don't know: 1) What parts are rubbing because nothing appears to be wearing but then again I can't exactly see the internals very well and the grinder is 20 years old so nothing, apart from the burrs, are shiny and new. 2) If I installed the new burrs correctly- the one with the ring is in the fixed position and I used the old Bunn screws because the new screws that came with the burrs did not appear to fit. 3) If I reassembled everything correctly- to rule this out I plan to put the worn burrs back in this evening.

Any and all advice will be greatly appreciated.

Mike

If metal powder is coming out, take it apart and inspect, whatever it is should be pretty obvious.