Bunn Grinder Bushing position

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TomC
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#1: Post by TomC »

So I have my Bunnzilla as torn down as I've ever taken it. With all credit going to Dan Remer who's helped me chop my G1 in half to create a mini-Bunnzilla, I'm stuck at a bit of a dilemma and the answers aren't very clear.

The Bunn G series has a bronze bushing that goes between the motor and fixed aluminum burr housing shown below. The pdf on Bunn's site shows this bushing with it's stepped-down side facing outwards towards the burrs (away from the motor). When I tore my unit down, the bushing was facing with the flat side towards the burrs, not the other way around. As well, the other noted Bunn expert on this forum, John Borella has his bushing oriented the same way I found mine.



Now, obviously to save time, my first step was to call Bunn directly. I had to get bounced to three different people until I finally got one of the guys who's familiar with these and how they're built ( he's assembled hundreds of refurbs, so I trust that). He said that while it wouldn't be a surprise that a pdf could be wrong, he assured me that the diagram was correct and the stepped side faced out towards the burrs ( part 6 below).



Dan didn't take his bushing out when he made his wooden case, so he's not sure. But it seems odd that both John and I both have grinders with the flat facet of the bushing facing the burrs, yet both are "wrong".

On the one I removed, you can see where the spring basically gouged a track into the soft bronze (hence why I chose to replace it).



Reverse side showing the "stepped" rim.



Has anyone else tore into their G-series to this point and able to chime in? It would make sense that the whole assembly would spin together, shaft, bushing and spring, but that means the bronze bushing is going to constantly "grind" against the soft aluminum. If the bushing isn't supposed to spin, I suppose you could get the spring cutting into it like what I'm noticing, but that seems to be an odd design. For what it's worth, the tech at Bunn said he rarely gives them much attention and spent more time talking about the spring.
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ira
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#2: Post by ira »

As far as I can tell, the bushing rub against anything. I think it's just trapped between the spring and the motor shaft. i thought it was just supposed to help keep grounds from getting behind it. I don't believe mine touches any aluminium. I replaced mine because it was inexpensive, but the old one didn't seem worn.

Ira

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JohnB.
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#3: Post by JohnB. »

My 2005 G3 was in as new condition when I bought it having seen very little use after being bought new for a cafe that went under not long after opening. The bushing in mine has the wide flange facing out against the spring, stepped portion facing in towards the motor. It was assembled that way by Bunn & that's the way it will stay. If the stepped portion faced the spring it would have to fit inside the spring as the spring pressure would eat up that step in short order. Since the spring just fits over the shaft I don't see that happening.
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