Titan Grinder Project - Page 14

[RapidCoffee]

John, I'll send you some burr resistant thermocouples.

Just make sure there's a Cimbali Max attached to them.

[AndyS]

He needs to rethink his explanation.

We are talking about differences among commercial grinders used in occasional domestic service. A Cimbali Junior or Mazzer Mini does not have its burrs heat up much in the sort of use that we home users put those grinders to, anymore than does a Robur, a Compak K10, or a Cimbali Max. It is quite honestly absurd to think otherwise.

The people making and posting about these observations are not using these grinders in cafes (where it doesn't much matter) but from their experience in a home setting. In a cafe, it doesn't matter if you pitch 2 or 3 shots down the drain every time the ambient humidity changes, if you are going to grind enough coffee in a shift to make 200 doubles. In a home, we notice this sort of thing because we are low volume infrequent users.

I think that Michael Teahan's explanation makes the most sense. It all revolves upon the length of the cutting/grinding surface, regardless of the type of burrs. Conicals have larger cutting surfaces than do most planars, and that is the explanation.

First of all, I said Philip "took a shot at an explanation." I don't think the "grind adjustment stability of bigger grinders" is something that he personally has noticed (nor have I). But since a bunch of you guys have observed this, I asked Philip if he could explain it. He was driving down I-5 in his car talking on the cell (handsfree, of course) and ventured a quick guess based on his experience. I repeated it here (as best as I remembered it) as a talking point to foster discussion. It wasn't intended to be a formal explanation.

Second, Philip told me that he's made actual measurements of coffee grounds temperature coming out of the burrs of various grinders. With Mazzer Mini grinders he said he's observed elevated temperatures after only about three shots ground in a row (easily typical in home use).

Third, what you're calling "Michael Teahan's explanation" does not "make the most sense." It presumably explains why some grinders make different coffee than other grinders, but it certainly doesn't explain why some grinders VARY more than other grinders.

[edited to remove some of my overreaction to Ken's original post]

[RapidCoffee]

...Philip told me that he's made actual measurements of coffee grounds temperature coming out of the burrs of various grinders. With Mazzer Mini grinders he said he's observed elevated temperatures after only about three shots ground in a row (easily typical in home use).

Actual measurements will trump BSing any day. But this topic did come up during the Titan Grinder testing, and Dave took some grinds temperature measurements. Based on temperature data taken in the chutes of the Mazzer Kony vs. SJ grinders, there was no compelling reason to believe that temperature plays a major role in grind quality, at least not for these grinders under typical home conditions.

Again, I'll observe that we need measurements taken in the grinding microenvironments produced by the cutting surfaces of the burrs. It's possible that the grinds are subject to rapid heating followed by rapid cooling, and this does impact flavor. If there were major differences between grinders, and temps correlated well to taste profiles in the cup, it would be worth pursuing. But right now that's even more BSing than speculations about particle size and shape (for which we at least have preliminary data).

Perhaps you could suggest a way to get near-instantaneous temperature measurements at the burr surfaces during grinding? I'm unaware of any equipment (some sort of super-duper IR thermometer?) that permits such measurements to be made.

[Ken Fox]

Actual measurements will trump BSing any day. But this topic did come up during the Titan Grinder testing, and Dave took some

The people that I know of who have made this observation online would very seldom grind three shots in succession (Andy's threshold), and this is unlikely to be their normal usage pattern, although it might happen on occasion. The people who I recall making this observation (of the need to change grind adjustments less frequently with conicals) include Dave, myself, Jim Schulman, Jason Casale, and to some extent Jeff.

The first time I recall this coming up was in a conversation I had with Jason Casale at the SCAA in Long Beach, 9 months ago; Jason had a Max and I had recently acquired 2 of them. We had both made the observation independently. Subsequently I saw it posted on the TGP and other related threads by others. Undoubtedly I have left some people out who have made this same observation.

In addition, when I did a mini blind tasting between the Max and an old Cimbali Cadet (same burr set and motor as the Junior), it was extremely obvious due to the side by side usage of these grinders; it is posted somewhere in the TGP thread. Only on very rare occasions did either grinder grind for more than ONE shot in a 10 or 15 minute period, no less three.

ken

[Matthew Brinski]

Based on temperature data taken in the chutes of the Mazzer Kony vs. SJ grinders, there was no compelling reason to believe that temperature plays a major role in grind quality, at least not for these grinders under typical home conditions.

Unless I misunderstood the way that the test was carried out, there is no compelling reason for me NOT to believe that temperature plays a role in the quality of the grinded coffee secondary to grinder activity. I say this because I interpreted the measurments to be from a sustained grinding of 1/2 pound of coffee. (Dave, if this is not the case, please correct me.) The problem is that people are looking at this test and drawing immediate conclusions that the issues of heat are overstated or not applicable to home use while referencing a single test that does not represent either home or cafe use anyways. At best, this type of grinder use represents a cafe which fills the doser rather than grind per shot, a practice which is considered poor.

I am being a bit critical because it is somewhat ludicrous to see conclusions drawn from tests that have had variables either introduced or removed from what is representative of real life application. For instance, although I am currently led to believe that the majority of grinder heat is a result of the burrs themselves, the motor does release a decent amount of heat. Electric motors are inefficient due to the energy required to start them. This is especially true of motors that are not being supplied power via 3 phase wiring. Again, I may be wrong in the way I interpreted the way the test was carried out, but the variable of intermittent "off/on" motor duty was removed from this test. That variable is responsible for a great deal of heat from the motor.

Yet, from this single test, there is opinion that heat issues have been "debunked" or misrepresented by others' current opinion and thought.

Just because we geeks have some decent instruments to obtain accurate data doesn't make our findings meaningful.

[Matthew Brinski]

The people that I know of who have made this observation online would very seldom grind three shots in succession (Andy's threshold), and this is unlikely to be their normal usage pattern, although it might happen on occasion.

Ken,

Maybe I am out of the norm, but when I make espresso at home, I usually make my wife and I (and sometimes my three year old) an espresso followed by a cappuccino every morning. With a seasoning shot, possible additional shots for grind adjustment (a sure thing when changing coffee), and four drinks, I easily prepare five to six shots in succession.

I'm not stating one way or the other about heat issues with that usage pattern, just giving my pattern which meets or exceeds the "thre shot" threshold.

.

[RapidCoffee]

Yet, from this single test, there is opinion that heat issues have been "debunked" or misrepresented by others' current opinion and thought.

To the best of my knowledge, nobody is claiming heat issues have been categorically excluded from grinder evaluation. If you have criticisms of the data that was presented, why don't you run your own experiments and generate new measurements for the rest of us to chew on? Further armchair quarterbacking is optional.

One more piece of speculation here, and then I'm done: coffee beans are subjected to high temperatures (400-500F) for long periods of time (many minutes) during the roasting process. Unless the beans are heated to much higher temperatures during the much shorter grinding process, this argues against heat being a major factor. Grind particle properties (size, shape) are more likely to play a significant role in determining pour characteristics, especially when evaluating grinder forgiveness (not taste).

[Ken Fox]

Ken,

Maybe I am out of the norm, but when I make espresso at home, I usually make my wife and I (and sometimes my three year old) an espresso followed by a cappuccino every morning. With a seasoning shot, possible additional shots for grind adjustment (a sure thing when changing coffee), and four drinks, I easily prepare five to six shots in succession.

I'm not stating one way or the other about heat issues with that usage pattern, just giving my pattern which meets or exceeds the "thre shot" threshold.

.

Matthew,

I don't recall you're ever having commented on the need or lack of need to change grinder settings with planar grinders vs. conical ones.

Of the people who have made this comment, most are either single or have spouses who don't drink coffee. I hate to dismiss an idea out of hand, but heat build up in commercial grinders used in a home setting as an explanation for this phenomenon simply does not pass the "sniff" test.

I'm personally exceptionally familiar with grinders using the Cimbali Junior 64mm planar burr set (includes the Cadet also), having used them for about 12 years. I've now been using Maxs, and was using a Compak K10 conical for some months. All of these grinders have seldom been used for grinding more than 40g of coffee at a time, and most usually about half of that. The frequency with which these planar grinders need adjustment for changes in coffee or humidity is about 1-2x per day. With the conicals the difference isn't subtle, it is obvious enough that anyone would notice it. The conicals have their grind settings changed 1-2x a week, tops.

ken

[cannonfodder]

I saw little benefit in the thermocouple in the grind chute test I did when I had the Kony and SJ out. So I did not bother to repeat the process on the rest of the grinders. I thought we had come to the conclusion that there are too many things happening inside that burr set at a micro environment level for the probe check to be of any real significance but it has been a few months since I read it.

I am content in knowing that this is not a single observation and appears to be consistent with the bigger is better theory of grinding burrs. The reasoning my elude us and having a measurable item for the apparent change would be nice but I am not going to obsess over it. I will leave that to the engineers that design these things. The validation of the observation is good enough for me. I think I will spin up the Robur for one last shot before she gets packed up and moves on.

[gscace]

Actual measurements will trump BSing any day. But this topic did come up during the Titan Grinder testing, and Dave took some grinds temperature measurements. Based on temperature data taken in the chutes of the Mazzer Kony vs. SJ grinders, there was no compelling reason to believe that temperature plays a major role in grind quality, at least not for these grinders under typical home conditions.

Again, I'll observe that we need measurements taken in the grinding microenvironments produced by the cutting surfaces of the burrs. It's possible that the grinds are subject to rapid heating followed by rapid cooling, and this does impact flavor. If there were major differences between grinders, and temps correlated well to taste profiles in the cup, it would be worth pursuing. But right now that's even more BSing than speculations about particle size and shape (for which we at least have preliminary data).

Perhaps you could suggest a way to get near-instantaneous temperature measurements at the burr surfaces during grinding? I'm unaware of any equipment (some sort of super-duper IR thermometer?) that permits such measurements to be made.

FWIW, comparisons of temperature measured just above the burrs and immediately after the cutting process done by a company that is heavily involved in grinder manufacture indicate that the work of cutting the coffee, the friction produced when coffee passes out of the burrset is remarkably similar between different manufacturers of flat burrsets and different manufacturers of conical burrsets. There apparently is some difference between flat and conical burrsets. The conclusion drawn from the comparisons was that there was little to gain heat-wise from rethinking burrset shapes, but lots to be gained in managing heat flow from other sources in the grinder. For our use - folks using commercial gear in a light duty environment, temperature issues are pretty much moot.

-Greg

[Nick]

Yer all wrong. It's simple geometry.

The threading on the grind adjustment collar between a Robur and a Super Jolly have a very similar pitch. In other words, one 360-degree rotation of the grind adjustment collar results in the same vertical movement of the upper burr set.

However, flat burrs sit completely parallel to each other. They're like a sandwich. When you move the upper burr set, say 0.10 mm vertically, the gap/distance between the burrs at the final cutting edges moves 0.10 mm apart from one another.

In a conical burr grinder, the grinder burrs are configured significantly differently, with the cutting edges converging at the "grind gap" at diagonal angles. 0.10 mm of upper burr movement does NOT widen the gap between the final cutting edges by 0.10 mm. It's something fairly smaller.

Anyone who's seen conical burrs (esp. Kony or Robur burrs) and flat (SJ) burrs can, I believe, visualize what I'm talking about. It's sort of hard to explain. (illustrations would help... but I'm too lazy)

That's why conicals "need less adjustment" than flat burr grinders. At espresso-grind fineness, one radial unit of collar adjustment/movement on a SJ equals about (just a guesstimate based on extensive experience) 3 to 5 units of movement on a Robur, when adjusting for flow rate.

[Ken Fox]

Yer all wrong. It's simple geometry.

The threading on the grind adjustment collar between a Robur and a Super Jolly have a very similar pitch. In other words, one 360-degree rotation of the grind adjustment collar results in the same vertical movement of the upper burr set.

However, flat burrs sit completely parallel to each other. They're like a sandwich. When you move the upper burr set, say 0.10 mm vertically, the gap/distance between the burrs at the final cutting edges moves 0.10 mm apart from one another.

In a conical burr grinder, the grinder burrs are configured significantly differently, with the cutting edges converging at the "grind gap" at diagonal angles. 0.10 mm of upper burr movement does NOT widen the gap between the final cutting edges by 0.10 mm. It's something fairly smaller.

Anyone who's seen conical burrs (esp. Kony or Robur burrs) and flat (SJ) burrs can, I believe, visualize what I'm talking about. It's sort of hard to explain. (illustrations would help... but I'm too lazy)

That's why conicals "need less adjustment" than flat burr grinders. At espresso-grind fineness, one radial unit of collar adjustment/movement on a SJ equals about (just a guesstimate based on extensive experience) 3 to 5 units of movement on a Robur, when adjusting for flow rate.

Nick,

We aren't talking about how far the adjustment mechanism needs to be moved; we are talking about how FREQUENTLY any adjustment needs to be made.

In a busy cafe, perhaps you have different standards and would adjust your grinders more frequently than we would in a home setting. We might decide, for example, that anything between 1.3 and 1.8 oz for a double was "satisfactory," and you might insist on 1.65oz. (numbers made up for purposes of the example).

What we're saying is that within the range that each of us would define to be an acceptable output for a double, that we can get that acceptable output without changing the grind setting as often with a typical conical than with a typical planar (but the typical planar grinders we are talking about are for the most part 64mm in diameter or less). We are saying that changes in the coffee and in environmental factors such as humidity, over time, make us tinker with grind settings less on conicals than on planars.

ken

[Nick]

It's sort of hard to explain. (illustrations would help... but I'm too lazy)

Nevermind...



The picture speaks for itself.

At standard web 72 ppi, I moved the top burr illustration exactly 15 pixels up (no lateral X-axis movement) on both.

The smallest gap between the two burrs will determine the primary grind size.

[Nick]

Nick,

We aren't talking about how far the adjustment mechanism needs to be moved; we are talking about how FREQUENTLY any adjustment needs to be made.

Ah. I hear ya. Wasn't paying close enough attention (never my strongest suit). Hope the illustration wasn't a complete waste of time.

Then here's my take two: because the Robur makes more fines, the "non-fine" bulk of the dose is made up of coarser particles than the SJ's planar burrs. Coarser coffee is less susceptible to environmental factors than finer.

That's my story and I'm stickin' to it.

[Ken Fox]

Ah. I hear ya. Wasn't paying close enough attention (never my strongest suit). Hope the illustration wasn't a complete waste of time.

Then here's my take two: because the Robur makes more fines, the "non-fine" bulk of the dose is made up of coarser particles than the SJ's planar burrs. Coarser coffee is less susceptible to environmental factors than finer.

That's my story and I'm stickin' to it.

Home usage patterns are hugely different than what one faces in a cafe. A typical home user will make some shots in the morning, then maybe an additional set or two of shots later during the day. It is not uncommon to have gaps of several hours between shotmaking sessions. During these gap periods, the environmental factors and the coffee itself can change.

Then, the equipment sets idle overnight, and gets used again the next morning. What would amount to be trivial waste in a cafe (adjusting grinders at the start of the work day) could amount to being hugely wasteful of coffee for a home user, on a percentage basis of the coffee that he or she uses. If a home user has to toss one or two shots each day due to the grind not being right, that might amount to 30 or 40% waste of all coffee that is ground, for a home user.

On the other hand, if the home user can go 2 or 3 or even 4 days between the need for changing the grind setting, that saves coffee.

There is also the issue of "how far off" is the "non-optimal" shot. My prior experience with 64mm planar Cimbali grinders was that when the shot was off, it was often bad enough that I wouldn't even use it in a cappuccino, it would go down the drain.

Contrasting this with both the Compak K10 and the Cimbali Max, those sorts of sink shots are rare. So, even if the shot isn't spot on, it is drinkable, and a small grind adjustment gets it back into a good range. With the planars it might take two attempts to get it back to a good setting.

So, for a home user concerned about coffee waste, the conicals and the hybrid Max conical/planar seem to be much easier to use and to economize on coffee waste, and on the time of the home barista.

ken

[Sedi]

Nick, even if the discussion was on the accuracy of adjustment and not on frequency of it, your geometric explanation for the more accurate adjustment with conicals is certainly not applicable for hybrids like the Max, were the fine grinding is by planner burs.

If the spectrum of particle size is determined by the fine grind area of the burs, then maybe grinders with planar burs with a large fine grinding surface should exhibit same behavior?, how often Major owners adjust?

If the particle size spectrum is similar and still large planar burs need more adjustment than conicals, then maybe the spectrum of size is not the main issue here. Did anyone consider how much the metal is deforming under different temperatures during the day or heat produced by the grinder?, if there is a small deformation of the burrs and the axis under different temperatures which is not negligible compared to fine particle size this might explain differences between frequency of adjustment with different grinders, not necessarily conicals and planar, and with different usage. If deformation size is negligible, I just gave it a shot.

[Nick]

Nick, even if the discussion was on the accuracy of adjustment and not on frequency of it, your geometric explanation for the more accurate adjustment with conicals is certainly not applicable for hybrids like the Max, were the fine grinding is by planner burs.

I specifically discussed the Mazzer grinders, because the grind adjustment collars have the same pitch (movement of the collar moves the burrs the same vertical distance). I don't know anything about the Max.

[gscace]

Nick,

We aren't talking about how far the adjustment mechanism needs to be moved; we are talking about how FREQUENTLY any adjustment needs to be made.

In a busy cafe, perhaps you have different standards and would adjust your grinders more frequently than we would in a home setting. We might decide, for example, that anything between 1.3 and 1.8 oz for a double was "satisfactory," and you might insist on 1.65oz. (numbers made up for purposes of the example).

What we're saying is that within the range that each of us would define to be an acceptable output for a double, that we can get that acceptable output without changing the grind setting as often with a typical conical than with a typical planar (but the typical planar grinders we are talking about are for the most part 64mm in diameter or less). We are saying that changes in the coffee and in environmental factors such as humidity, over time, make us tinker with grind settings less on conicals than on planars.

ken

Ken,

That depends on what it is that causes the need for grinder adjustment. Folks assume that it's the coffee that changes, but we see here that conicals appear to behave differently than flat-burr grinders in their perceived need for adjustment. The coffee, however, stays constant in this (same type presumeably), which could lead one to the conclusion that the grinder may be moving around as well. Grinder housings are aluminum, which has a pretty high thermal coefficient of expansion. Depending on the design, it's entirely possible that burrs move relative to each other quite a bit when temperature changes. This would be due to motors being mounted in one part of the housing (near the bottom), while the upper burrs are a spaced quite a distance away, usually threaded into the top. Thermal expansion in grinders using a conical burrset is likely to be less of a problem than for flat-burr grinders for the reason that Nick presents. I can think of other sources of grinder instability that would be less of a problem for conicals compared to flat-burr. Motor shaft end float would be one, as would deflection under stress from cutting the coffee.

-Greg

[Nick]

Home usage patterns are hugely different than what one faces in a cafe.

Yes and no, but I can still confirm that the "conicals seem to need less frequent adjustments than flat burr grinders" rings true in a cafe setting nonetheless.

There is also the issue of "how far off" is the "non-optimal" shot. My prior experience with 64mm planar Cimbali grinders was that when the shot was off, it was often bad enough that I wouldn't even use it in a cappuccino, it would go down the drain.

Contrasting this with both the Compak K10 and the Cimbali Max, those sorts of sink shots are rare. So, even if the shot isn't spot on, it is drinkable, and a small grind adjustment gets it back into a good range. With the planars it might take two attempts to get it back to a good setting.

So, for a home user concerned about coffee waste, the conicals and the hybrid Max conical/planar seem to be much easier to use and to economize on coffee waste, and on the time of the home barista.

I wasn't kidding with my take-two explanation.

I recently wrote an article about grinders (mostly basic, "what every retailer/barista should know about grinding") for the current issue of Fresh Cup magazine, and I've been thinking about grinders a lot lately. Also, revisiting H-B after having not in many months yielded this gem of a post from Mr. Weiss. It's inspired me to inquire within the SCAA and among some of my like-minded colleagues in the industry about doing a more comprehensive study of the differences among grinding burrs (where the action happens) for espresso.

This might be an oversimplification, but I'll try anyway: the more fine particles that are produced, the more coarse the rest of the dose (the "non-fine" particles) will be, compared to a dose with fewer fines, for which the non-fine particles need to be an overall smaller size to, let's call it "make up for the lack of fines."

I think that results in a more environmentally-sensitive grind (sensitive to humidity and temperature changes) for grinders that create fewer fines.

That all said, I believe it has more to do with the constitution of the ground coffee itself, rather than directly attributable to mechanical or physical attributes of the grinders.

[cannonfodder]

But in the particle analysis and SEM analysis of comparably adjusted grinders, there was no significant delta between burr sets. We thought we would see an increase or decrease in the fines (or other particle sizes) that would correlate to the burr set. At that point you would be able to look at a histogram of the particulate and know that the sample you are looking at is from a flat or conical burr. There would be a defining trend to the graph for each burr type, but there was not.