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Large conical vs flat burrs: Consistency and pour characteristics? - Page 2

Postby GlennV on Thu Feb 16, 2012 11:44 am

Yes, thanks for that Doug. I spent a happy 1/2 hour crushing coffee beans with my tamper after reading it.

I suppose my question is whether Jim's observation (that 15g of virtually any coffee flows roughly the same after being ground at the same setting on a large conical) holds across different roast levels.

As for burr spacing, on my machine this varies between about 160 microns for the lighter roasts to 280 microns for the N.Italian style ones, which is interesting given that this range corresponds to a minimum in the particle size distributions published here, which show peaks at around 50 and 500 microns. As is typical for espresso burrs, the grooves extend to the outer edge - presumably allowing the larger particles to escape. I typically see a roughly 5s change in shot timing for a 10 micron change in burr spacing. In comparison to this, the 160 to 280 range is huge.
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Postby EricBNC on Thu Feb 16, 2012 12:42 pm

orphanespresso wrote:Eric...I have the same experience with the small conicals that you observe and like you, I am approaching this idea of coffee grinding as a physical process which can be understood on strictly physical terms. I don't think there is any magic in there with the big titan burr grinders...just a good burr and some superior build quality to run it. It is just the same with espresso machines and extractions...no magic in there and it seems that if one can understand and control all of the parameters then one should get a predictable result.

With grinders, there are no real good tools to see what is happening on the grind and everything is interpreted after the fact through pulling a shot and getting in to some subjective evaluations. You like the K30 for the shots you can make when using it. I would probably like it as well. I wish I had one. I always enjoyed our B. Vario for various reasons but now prefer either the big conical burr or big flat burr in other formats...I am just a lot more able to tweak the shots with these larger burr grinders and that is interesting to me...not better, just a phase I am going through I suppose. A lot of it is personal taste.

Again, as I said, I am not an engineer or coffee scientist, simply spend a good bit of time thinking about these things, like many other people do. :)

I am no expert here either - I have only experienced shots from a Robur, Mythos, K30, Major, SJ, B.Vario, Mini (burr set), B.Preciso, La Pavoni PBC, the Krups Conical, and some hand grinders. Some experience yes, but not enough to be an expert.

From The Vario on up (in both size and price) I have experienced layered flavors worthy of remembering - I have experienced some very good shots on the smaller grinders too so I do not consider these to be incapable of quality shots if given the right coffee beans to grind.
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Postby erics on Thu Feb 16, 2012 3:36 pm

And just to put things in a size perspective -

Image

Grinder speeds should really be compared in terms of linear feet per second (fps) vice rpm.
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Postby malling on Thu Feb 16, 2012 4:22 pm

You are right R/ps dosn't tell the whole story.

There is defiantly too much difference between conic and flat burrs, that it dosn't really make sence to use r/ps. Instead we should really use mm or feer per second.

Eric do you know how Many mm/inches a major and k10 rotate per second.
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Postby EricBNC on Thu Feb 16, 2012 4:39 pm

The shape could probably contribute as much as the size and speed - will add this though - conventional wisdom (and Mazzer pricing) puts the Mazzer Mini in a deserved lower place compared to the Mazzer SJ - with the slower 450 RPM speed I experience (could be killing the motor for all I know - probably is even though the sound never changes) the results are Vario/SJ like in the shot. Speed likely matters a lot.

In case any one thinks I am calling out Doug from OE - please do not. He is the best thing to happen to hand grinders in 50 years (a quick search of my posts will show my love of this art form) - I question him because he is likely to have the answers - looks like he thinks about the same questions that I find myself thinking about - not gonna save the world but it might make a better cup of coffee. :D
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Postby Flasherly on Thu Feb 16, 2012 6:04 pm

I've a motorized large conical grinder from Spain. Whereas with my roaster, it's almost inconceivable not to have to change grind settings if popping a freshly roasted batch into the grinder, as opposed to coffee I may have roasted from a week ago and subsequently frozen. Since espresso roasts are more fully developed into darker roasts, than the lighter single-origin roast, at least with my grinder, I'm able to use the grinder's full adjustment range in the former case. Single origin roasts taken to the first crack and hardly further, my motor simply enough will bog over itself if adjusted for too fine a grind. Of course a wider range then is widest of all within a provision that a widest sample of beans are to be indiscriminately roasted for espresso profiles.

I understand my conical burrs are somewhat larger. They do nevertheless fall within a branded name of burrs employed for constructing Pharos. Notwithstanding the Spanish motor assembly, I've run consequent for perhaps 200 lbs. of roasts. Characteristics, as I'd say in regarding such a motor, perhaps better motors or yet a competent design of hand grinder is less apt to be hindered by when dealing with harder casings of lightly roasted beans;- silt effortlessly ground off carbonized cinder that's roasted aways longer than necessary isn't of any more concern than most profiles I daresay are closer than not to an espresso roast.
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Postby malling on Fri Feb 17, 2012 6:23 am

What grinder are you using, or is it selfmade.

I'm only familiar with the Well known conic grinders from Mazzer and co. And I havn't experienced that much problems. Then again I never use or drink Dark roasts.
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Postby expy98 on Fri Feb 17, 2012 6:40 pm

Hi Glenn,

FWIW, this is what I've observed w/ my SJ and Pharos on a pump machine:

I roast w/ a Hottop, all SO and eject before the start of 2nd crack or as soon as I
hear the onset of 2nd crack.

The only beans in my limited inventory that I could get the SJ to pull shots at around 3 clicks from
the zero point are Ethiopia or Brazil (or a blend of those 2). All others, I have to set the
SJ to near zero point as well as upping the dose significantly to get the shot timing to come close.
But like you've said, even then, it's still quite finicky. The same thing happens w/ my other 2 friends w/
SJs (all 3 of us have tried new burrs as well) and 2 w/ Rocky DLs. The common denominator is that I'm the one supplying the roasted beans, so it's highly likely that I'm the cause of the problem.

So for a while I pretty much gave up on many beans for SO espresso (yemen, kenya, sumatra, costa rica, panama, el salvador, columbia, java...) and used them for other purposes instead.

Until... I got the Pharos...

Once I set the grinder setting, all the beans that I've never been able to pull as SO successfully
before, now all work flawlessly. Everything works at between 13-16g dose at the same grind setting.
I haven't changed the grind setting since the last time I'd disassembled to clean and realign about 3 months ago and I change to a different bean every week (one batch from the Hottop lasts about a week and I rarely, never?, use the same bean again the following week).

Also, using bottomless PFs, I used to WDT, nutate w/ the SJ and in the 2 years of using it, I believe I can count on my fingers and possibly a few toes how many times I got the perfect looking pours. Admittedly that's my lack of skills.

With the Pharos, I dump straight onto the basket sitting on a .1g scale, if the mound is really off-centered, I tap it lightly on the mouse pad (my tamping pad) a couple of times to even it out a bit and tamp straight down, no more WDT/nutate. Just about every pour is visually excellent. I never got this kind of consistency w/ the SJ.

I have a piece of masking tape applied to the lower portion of the Pharos with notes of all the different origins and dose used. I don't have it in front of me but will snap a pic and post later.
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Postby GlennV on Fri Feb 17, 2012 7:18 pm

Excellent. Many thanks for that expy. Looks like the pharos has just made it to the top of my birthday list!
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Postby darilon on Fri Feb 17, 2012 9:40 pm

GlennV:

I just made up my mind to get one as well. Read the owners thread in this forum, it's chocked full of great ideas. Note that you will have to take the first 30 pages with a grain of salt as the latest Pharos has three nuts for locking the handle and adjusting the grind as opposed to one when it first shipped (plus a few other mods along the way). Expy98's post sure makes it sound like a winner, doesn't it? Also for the OP, that Pharos owners thread has a lot of info about folks comparing different grinders/burrs, etc.
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