Tutorial on static electricity in grinders - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
SeanSheep
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Postby SeanSheep » Feb 03, 2013, 5:20 pm

Terranova wrote:Will it make a difference to fit a lower funnel in steel, connected to a metal wire which is grounded to the sink or so ?


I think there would need to be an unbroken conductivity path between the burrs and anything that the grinds touch. So a theoretical wire would need to go from the burrs themselves, a conductive lining on inside of the funnel, then continue on and connect with the portafilter somehow. From my understanding, it wouldn't need to be connected to earth, it's just that everything involved in touching the coffee from the point it is ground onwards needs to be connected to each other. Glad to be corrected though!

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bostonbuzz
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Postby bostonbuzz » Feb 03, 2013, 8:42 pm

Are HG-one and mazzer style grinder burrs grounded? Does anodizing affect conductivity?
LMWDP #353

salvatore
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Postby salvatore » Feb 03, 2013, 9:13 pm

When I probe between the funnel and the rest of the parts of my HG One, there is no continuity. In fact, you do not even get continuity across the anodized surfaces themselves, i.e., flywheel to flywheel, funnel to funnel, etc.

Where there is continuity is between the screws and bolts throughout the unit, however, I don't think this matters if the anodizing is insulating the funnel. FWIW, once when dropping the funnel down into the top of my OE funnel atop my pf, I noticed a spark cross between the two. I found this very interesting. Also of note, I don't have any issue with grinds sticking to the underside of the burrs, but solely to the inside of the funnel.

I'd really like to see what would happen if a non-anodized funnel was attached to the bottom of the unit. I have a feeling it might improve things dramatically. Perhaps something in stainless steel?
"L'unico modo per liberarsi da una tentazione è cedervi." Oscar Wilde

coffeedom
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Postby coffeedom » Feb 03, 2013, 11:54 pm

I suspect that the funnel may make a difference as well. If the burrs and funnel were coated in something with high electrical conductivity like Titanium Nitride, maybe a good portion of the static under low humidity conditions would not occur.

Perhaps Frank can test this by running the HG One with his coated burrs and no funnel or a modded funnel if that is possible.

toobs1234
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Joined: Jan 24, 2013, 8:52 pm

Postby toobs1234 » Feb 04, 2013, 2:02 am

Guys, I really didn't want to make this thread about the HG-1. For the record, I think the HG-1 is a really neat design. I also think it's a very cool project for two friends to undertake and I wish them the best. I'm just too lazy to use it. Spraying your beans for sure will solve static problems. For somebody that weighs their beans and then grinds them by hand, this shouldn't be a laborious extra step.

The purpose of this thread was to try to clear up some of the apparent misconceptions flying around this forum. I was particularly hoping that it might help some of the guys here who are taking their passion to the next level and actually constructing/modifying equipment who maybe don't have a background in physics. I don't mean to be condescending, but I did major in physics and used to work in engineering, including on Fermilab, and that hopefully wasn't just a waste of time.

Regarding the HG-1. I truthfully don't know if you can significantly reduce the amount of static by modifying the materials simply because of the nature of the design. The grounds don't spend a lot time in contact with the funnel after exiting the burrs. I also don't know if reducing static will reduce the amount of buildup that is experienced in the funnel, it does make sense that it would, though.

The things that can be done to reduce static are:
1) construct or coat the funnel and whatever vessel you are collecting the grinds in with a conducting material...one that won't oxidize.
and
2) if you can, implement a conductive path from the funnel and the collection vessel back to the burrs. If this is not possible, run wires from the funnel and collection vessel to ground. Careful about the sink, though. My sink isn't grounded (plastic pipes).

An extra step to try would be to place a grounded conducting wire grid at the base of the funnel--analogous to the static grids in a lot of electric grinders.

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galumay
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Postby galumay » Feb 04, 2013, 3:22 am

or....just move to the tropics, better weather, better fishing, no static at all with your HG-One. Perfect, eh?
LMWDP #322 i started with nothing.........i still have most of it.

scareyourpasenger
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Postby scareyourpasenger » Feb 04, 2013, 12:54 pm

toobs1234 wrote:An extra step to try would be to place a grounded conducting wire grid at the base of the funnel--analogous to the static grids in a lot of electric grinders.


This is exactly what I was thinking. This s present on many commercial grinders and it seems to have two different possible effects. The first being static and the other breaking up the clumps so that it might not need wdt. Both are the issues that I have with the HG one and is keeping me from jumping from the Pharos.

Netphilosopher
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Postby Netphilosopher » Feb 05, 2013, 3:54 pm

So, a couple of things:

What about static with a Hario Mini Mill Slim? (Ceramic burrs).

And why does everything respond with 3-4 drops of water in 25g of beans with a nearly complete dissipation of static?
Ross Droplet Technique-Eliminating Grinder Static

toobs1234
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Postby toobs1234 » Feb 05, 2013, 9:56 pm

bostonbuzz wrote:Are HG-one and mazzer style grinder burrs grounded? Does anodizing affect conductivity?


no, don't know, and anodizing creates an insulative surface on the metal :)

toobs1234
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Postby toobs1234 » Feb 05, 2013, 9:56 pm

galumay wrote:or....just move to the tropics, better weather, better fishing, no static at all with your HG-One. Perfect, eh?


you're the smartest man I ever met

 
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