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New-to-me Bunn G3: cleaning, grind retention...
mtbizzle
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Posted on 08/02/2020 7:16 PM
Recently picked up a used Bunn G3 grinder. Hoping to eventually throw in SSP (silver knight?) burrs to make it a 'Bunnzilla'. espressotool.com/...

Cleaned it today w/ a brush and some soap. The auger looks funky. Will this be a problem?

i.imgur.com/OC3889U.jpg

Have also had problems with retention. I'm hoping to use this as a single dose grinder for brew only, so the retention is frustrating. Any tips on ways to deal with the retention? I have heard of people using things like bellows to use air to force the retained coffee thru, but don't know of anything that has been used for the Bunn G series.
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
allenb
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Posted on 08/03/2020 10:50 AM
Does the auger appear damaged or are you just wondering why it looks different than expected?

On retainage with commercial grinders with gravity or spring type chaff breakers, there is unfortunately a portion left behind within the mechanism from each grinding session by design. All grinders to some degree do this. When I was using a grindmaster grocery store variety grinder a while back, I made a habit of flipping the chaff breaker lid back and forth several times while still running which seemed to drop out most of the grinds from the discharge chute leaving very little behind. When I did not do this, there would always be a teaspoon or so left in the discharge chute.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
mtbizzle
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Posted on 08/07/2020 7:52 PM
Thanks for the reply Allen.

So the auger clearly appears rusted, I guess I was mainly concerned that this would continue to worsen and pose some sort of problem. Like rust flaking off into the grinds, or some problem with the operation of the auger, I suppose not though. If there is an easy fix I might as well do it while I'm working on the grinder. Will sanding take this right off?

An actual issue I'm running into. The auger spring is stuck. I'm planning to do the sanding method of burr alignment - https://www.scott...ur-grinder - which requires removal of that spring. I've yanked on it quite a bit, and heated it with a heat gun, no dice. Maybe there is some product that won't damage the metal but could loosen it -- WD40, acetone? I'm not sure what the issue is my guess would be somehow coffee oils/rust? i.imgur.com/f6L9cU7.jpg
Edited by mtbizzle on 08/07/2020 9:13 PM
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
allenb
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Posted on 08/08/2020 6:03 PM
For the stuck spring and for helping dissolve the rust on the outside of the auger I would try a penetrating oil that is typically used for breaking rusty or seized parts loose and this one gets very good ratings:

https://www.amazo...6YFW7JZMSF

Take a wire brush to the auger but be careful not to wire brush while its wet with penetrant or you will wear it and the obvious danger to eyes. When all done, clean everything with acetone or naptha to completely remove all traces of penetrating oil.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
mtbizzle
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Posted on 08/11/2020 7:01 PM

Quote

When all done, clean everything with acetone or naptha to completely remove all traces of penetrating oil.


Very good. I got it out after a lot of oil and elbow grease. I know acetone readily evaporates (vaporizes?). Will it evaporate completely, such that the acetone is a non-issue when it comes to grinding coffee?

I actually have essentially the same question, relating to a different project. A month ago I got a La Pavoni professional, 1996. It is really beautiful, however, there is a lot of sediment in my flush water, so I have not used it yet. Trying to track down source, I noticed the portafilter lining/lacquer(?) is peeling. Would acetone be safe to strip the portafilter - just wait for evaporation & clean with water?

i.imgur.com/GAnHwkK.jpg
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
allenb
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Posted on 08/12/2020 7:52 AM
As with any fast evaporating solvent or even water for that matter, you need to find a way to remove the debris laden solvent before it evaporates and leaves the stuff you just loosened on the part. This could be by wiping with a rag while it's still wet or by pouring the solvent over the part which should drag the loosened debris into the container you're working in or combination of the two.
Acetone, to my knowledge, doesn't contain anything that would leave any residue and is why it's used in labs for parts and optics cleaning. Not sure about naptha.

Your portafilter shouldn't have any lacquer coating on its interior. Are you sure its a clear film flaking or could it be the chrome plating?
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
mtbizzle
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Posted on 08/12/2020 6:47 PM

Quote

allenb wrote:

Your portafilter shouldn't have any lacquer coating on its interior. Are you sure its a clear film flaking or could it be the chrome plating?


I believe the copper/brass La Pavonis (mine is a copper/brass La Pavoni professional c. 1996) have a lacquer coating on all parts. I think that is what this is. I'm just going off of what I have read though, about the clear coat on copper/brass Pavoni's, I don't know enough to judge myself. No chrome that I'm aware of anywhere
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
allenb
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Posted on 08/13/2020 4:48 PM
That's very interesting that they would apply any kind of clear finish over brass in an area where near boiling temperature espresso readily runs across. If they did this, and I also saw posts on other sites where people have noticed a lacquer type finish flaking off, then they are very odd ducks and should be locked up for at least one night in the slammer and forced to drink institutional stale coffee for 12 months.

I would give the portafilter a soak in lacquer thinner over night (metal parts only) until its totally removed and leave it uncoated.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
mtbizzle
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Posted on 08/13/2020 10:41 PM

Quote

allenb wrote:

That's very interesting that they would apply any kind of clear finish over brass in an area where near boiling temperature espresso readily runs across. If they did this, and I also saw posts on other sites where people have noticed a lacquer type finish flaking off, then they are very odd ducks...


This is from another user:

Quote

The brass and copper lanpavonis can be quite frustrating, for example for some crazy reason they lacquer the surfaces, which although nice when new, as soon as you get any water ingress the coating goes milky, they look fabulous stripped back and hand polished, even look nice to be allowed to tarnish and age but each to their own
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
mtbizzle
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Posted on 08/19/2020 8:29 PM
i.imgur.com/CKiuaQP.jpg
Roast: Kaldi wide, SR800 + projects
Grind: Lab sweet, Bentwood, giota w/ MP burrs, Commandante
Pull: Decent, La Pavoni, Elektra Microcasa a Leva, Faemina anno 60, Kim Express
 
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