Posted Sun Jul 5, 2009, 8:51am Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
cappuccinoboy Said:
...first and most important on same size OD (outside diameter) and same number of rotations conical have a much lower peripheral speed = less heat generated, "softer" contact with the bean ...
While it seems you have learned a bit about burrs (apparently what is generally purported by machine manufacturers), here you are technically incorrect about the physics of rotation. The relationship is determined by a simple law: Two objects with the same outside diameter and rotational velocity will have the same peripheral speed:
r x w = v Where r is radius, w is angular velocity, and v is peripheral speed.
But there is no change in heat transfer to the grounds due to burr rotational velocity. In home use these professional grinders run for very brief periods, not long enough to build any heat. Experimental measurements have shown that the Mazzer Major at 1600 RPM doesn't heat the grounds any more than the Mazzer Robur at 500 RPM.
It is true that the larger grinding surface of conicals can allow a conical burr to grind the same amount per unit time at lower rotational speed in many cases. For example, the Macap 68mm conical grinds a regular double shot a tad faster at 400 rpm than the Mazzer Super Jolly 64mm flat burr at 1600 RPM. Conicals can also be more forgiving in terms of adjustment.
But the Mahlkönig has 65mm flat burrs and grinds more than twice as fast as the Macap 68mm conical (albiet the Mahlkönig runs at 1600 RPM). In this case the difference in grinding speeds between the Mahlkönig and Super Jolly can be attributed to the burr design having more aggressive cutting angles, and if you were to install the new Titanium alloy burrs available for the Super Jolly (with similarly aggressive cutting angles) it would grind as fast as the Macap conical or the Mahlkönig K30.
cappuccinoboy Said:
...Noise I believe is strictly a matter of housing because when you "impact" a bean logics say that at higher speed you produce more noise, and this could mean that a conical is supposed to be quieter, and that does not always happen in real life, but you can always verify that by placing your noisy grinder into a cardboard box......
You're correct that noise is mainly due to the build specifics. Noise can be attributed to a number of things, but not speed of burr rotation.
My fastest-motor grinder is also by far the quietest. It's not the housing per se, but rather seems related to burr geometry and motor mounting. For example, the less expensive conical grinders are some of the loudest available...sounding like an airplane jet engine but the German flat burr grinder has rubberized motor mounts to isolate the motor assembly and it is amazingly quiet
cappuccinoboy Senior Member Joined: 27 Jun 2009 Posts: 790 Location: MILANO Expertise: Professional
Espresso: Milano pod, Milano fully... Grinder: grind on demand
Posted Sun Jul 5, 2009, 11:05am Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
JonR10 Said:
While it seems you have learned a bit about burrs (apparently what is generally purported by machine manufacturers), here you are technically incorrect about the physics of rotation. The relationship is determined by a simple law: Two objects with the same outside diameter and rotational velocity will have the same peripheral speed:
r x w = v Where r is radius, w is angular velocity, and v is peripheral speed. ........................... You're correct that noise is mainly due to the build specifics. Noise can be attributed to a number of things, but not speed of burr rotation.
My fastest-motor grinder is also by far the quietest. It's not the housing per se, but rather seems related to burr geometry and motor mounting. For example, the less expensive conical grinders are some of the loudest available...sounding like an airplane jet engine but the German flat burr grinder has rubberized motor mounts to isolate the motor assembly and it is amazingly quiet
jon you should know better : flat burrs are individually precision machined and both have the same OD, conical burrs are machined in set of two where the outside diameter refers to the upper burr, while the lower burr (the one actually rotating inside the upper one) is much smaller. I guess (but tomorrow I will be precise because I am actually going to calibrate), that in a 63mm conical the lower burr diam. is no more than 44-45, in a 47mm the lower burr is no more than 32-33, and in a 38mm the lower can be 23-24 : if you put in the right facts I bet even your formula will give a much lower peripheral speed of conical burr..... You are right about what you call German grinder : the day Italian manufacturers do realize that they can get higher price for "better" grinder, they will come out with something comparable,... and it is the sole way to go since most of the world can build a cheaper piece of equipment (of any kind), and the Know how we have can only be used to build better .......
Actually, I do know better already :-) The formula given is generic and absolutely correct in the strictest sense.
In a way, I was just poking fun at your words. It sometimes seems like you quote advertising literature from manufacturers like scientific facts when in general such information is not supported (or maybe only partially true).
It's true that the higher-end conical grinders are generally made to run at slower RPM and therefore have slower tangential speed at the point where the burr meets the bean (you called this peripheral speed).
cappuccinoboy Said:
the day Italian manufacturers do realize that they can get higher price for "better" grinder, they will come out with something comparable,... and it is the sole way to go since most of the world can build a cheaper piece of equipment (of any kind), and the Know how we have can only be used to build better .......
I guess I don't understand your point here. Are you saying the Italians don't build expensive grinders? Have you seen THIS ONE and THIS ONE, and what about THIS ONE??
IMAWriter Senior Member Joined: 4 Jul 2002 Posts: 5,464 Location: Brentwood, TN Expertise: I live coffee
Espresso: Nothing at the moment Grinder: Vario-W,Preciso-Esatto/KyM... Vac Pot: Adcraft SS, Yama 8 cup Drip: Brazen.Chemex, Hario, Clever... Roaster: Behmor 1600, CO/UFO combo
Posted Sun Jul 5, 2009, 12:14pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
Cap boy.....methinks you might want to gracefully withdraw from THIS battle! LOL Jon is an engineer, but in true R10 fashion is giving you a gentle pat on the posterior, but at the same time questioning your scientific method. besides, this conical/v flat burr thing is to me, all about taste anyway. By the way, you list yourself as a professional, yet your gear appears to be pod oriented. Whoops...don't want to get into THAT discussion. However, as a manual grinder owner, I do agree with you that for whatever reason, a somewhat miniature in stature conical in my manual does pretty much as superior a job as does a Mazzer mini, close to an SJ.
cappuccinoboy Senior Member Joined: 27 Jun 2009 Posts: 790 Location: MILANO Expertise: Professional
Espresso: Milano pod, Milano fully... Grinder: grind on demand
Posted Sun Jul 5, 2009, 12:22pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
JonR10 Said:
Actually, I do know better already :-) The formula given is generic and absolutely correct in the strictest sense. In a way, I was just poking fun at your words. It sometimes seems like you quote advertising literature from manufacturers like scientific facts when in general such information is not supported (or maybe only partially true). It's true that the higher-end conical grinders are generally made to run at slower RPM and therefore have slower tangential speed at the point where the burr meets the bean (you called this peripheral speed). I guess I don't understand your point here. Are you saying the Italians don't build expensive grinders? Have you seen THIS ONE and THIS ONE, and what about THIS ONE??
*You insist on poking fun at my words (but beware of boomerangs..)... at same RPM tangential speed is lower because lower burr in conical is of much smaller diameter: I do not read much manufacturers advertising literature (BTW you did not answer my post answering yours in :Fully automatics....), but in Naples they have a say stating that every mother finds beautifull her ugly son .....(I can say but not write in actual Neapolitan words) *I was only referring to the fact that I understand, although I could be wrong, that the Malkhonig is the most expensive grinder out there :the three examples that you give me kind of support what I said. *With ref. to noise in a grinder you get the mechanical noise of motor and the noise of beans actually beeing ground : motor noise can be dampened (like the Germans did), noise of beans is just a metter of sound transmission (body shape and size)
This is a re-statement of the formula, of course it's true.
cappuccinoboy Said:
*I was only referring to the fact that I understand, although I could be wrong, that the Malkhonig is the most expensive grinder out there :the three examples that you give me kind of support what I said.
Two of the three were roughly the same price at the Mahlkonig, and the Mazzer Robur-E is 50% higher.
cappuccinoboy Said:
*With ref. to noise in a grinder you get the mechanical noise of motor and the noise of beans actually beeing ground : motor noise can be dampened (like the Germans did), noise of beans is just a metter of sound transmission (body shape and size)
I disagree heartily. If you'd seen the evidence and personally tested and compared grinder designs then you'd most likely not make such an assertion. The science of vibration and noise is very complicated
The Germans clearly did some engineering work to make the Mahlkonig so quiet, it's not just a matter of dampening motor noise (electric motors run VERY quietly themselves unless something is horribly wrong mechanically)
Pietro - perhaps you claim not to read manufacturer's information but as a dealer of these machines I dare to say that you have probably read and re-read such material so much that now it's become much of the basis of your arguments...
JasonBrandtLewis Senior Member Joined: 9 Dec 2005 Posts: 6,099 Location: Berkeley, CA Expertise: I live coffee
Espresso: Elektra T1 - La Valentina -... Grinder: Mahlkönig K30 Vario -... Vac Pot: Yama 5-cup Drip: CCD, Chemex Roaster: No, no, not another...
Posted Sun Jul 5, 2009, 1:09pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
The Mahlkönig K30 ES is available from a US-based vendor for $2,150.00, and is available in 110v (North American "home," as opposed to "commercial," electric current). Please note, I have a Mahlkönig K30 Vario, the stepless version of the above grinder, in 110v.
The Elektra Nino is available from the same American vendor for $2,995, but only in 220v (European) current.
The Mazzer Robur is also available from the same vendor for $2,195 -- in a 110v model. But the Robur 220v model is $2,321.80.
All three of these Italian grinders are more expensive than the Mahlkönig as I am checking prices on the afternoon of 5 July 2009.
cappuccinoboy Senior Member Joined: 27 Jun 2009 Posts: 790 Location: MILANO Expertise: Professional
Espresso: Milano pod, Milano fully... Grinder: grind on demand
Posted Mon Jul 6, 2009, 12:28pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
JonR10 Said:
While it seems you have learned a bit about burrs (apparently what is generally purported by machine manufacturers), here you are technically incorrect about the physics of rotation. The relationship is determined by a simple law: Two objects with the same outside diameter and rotational velocity will have the same peripheral speed:
r x w = v Where r is radius, w is angular velocity, and v is peripheral speed.
My fastest-motor grinder is also by far the quietest. It's not the housing per se, but rather seems related to burr geometry and motor mounting. For example, the less expensive conical grinders are some of the loudest available...sounding like an airplane jet engine but the German flat burr grinder has rubberized motor mounts to isolate the motor assembly and it is amazingly quiet
cappuccinoboy Senior Member Joined: 27 Jun 2009 Posts: 790 Location: MILANO Expertise: Professional
Espresso: Milano pod, Milano fully... Grinder: grind on demand
Posted Mon Jul 6, 2009, 12:47pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
IMAWriter Said:
Cap boy.....methinks you might want to gracefully withdraw from THIS battle! LOL Jon is an engineer, but in true R10 fashion is giving you a gentle pat on the posterior, but at the same time questioning your scientific method. besides, this conical/v flat burr thing is to me, all about taste anyway. By the way, you list yourself as a professional, yet your gear appears to be pod oriented. Whoops...don't want to get into THAT discussion. However, as a manual grinder owner, I do agree with you that for whatever reason, a somewhat miniature in stature conical in my manual does pretty much as superior a job as does a Mazzer mini, close to an SJ.
I do appreciate your help, but I think I can hold my own with Jon, after all is just theory (his) against daily practice (mine) : but I do accept that there is quite a bit to be learned from these fights.... Since there is no change in taste of brew (with either method), believe me it is just a matter of manufacturing choice of giving an option to the customer, who will be happier knowing that he could have chosen either method since he will always be certain that he did chose the best one....... About pods if you were a manufacturer you would be aware that the majority of people out there are just normal decent people who love to enjoy a cup of "decent" espresso without having the fuss of going through rituals in the search for the "perfect" one, and if that "decent" cup turns out to be "good" than they are just happier... Of course out there are also a lot (vast minority though) of never satisfied people looking for more .... and willing to spend more : so, it is all about marketing .....
Posted Mon Jul 6, 2009, 1:38pm Subject: Re: Technically and Mechanically - Conical vs Flat Burrs
You seem to think I am just giving theory but I am referencing actual test data to back up my assertions. Also, it might surprise you to know that I have been making espresso every day for over 20 years, so I have a bit of experience myself, sir. In my profession, testing results are much more credible than other unsupported claims. ;-)
cappuccinoboy Said:
Since there is no change in taste of brew (with either method), believe me it is just a matter of manufacturing choice of giving an option to the customer, who will be happier knowing that he could have chosen either method since he will always be certain that he did chose the best one.......
This is not correct (another technically incorrect assertion). Maybe "seasoned" coffee all tastes the same no matter what grinder you use, but this is not true for fresh artisan beans/blends.
Testing has been done that shows a different particle size distribution from conical vs. flat burrs. This indicates that each burr type has it's own characteristic grind, and some folks can certainly taste the difference. This is also why the conical burrs seem more forgiving of grind adjustment.
Here are some links for testing threads that may be enlightening for you (they were for me):
CLICK HERE to see evidence of particle size distribution differences between conical and flat burrs.
CLICK HERE to see evidence that there is no difference in grounds heating between flat and conical burrs (home use)
CLICK HERE to see taste testing performed with various grinders by a professional cupper.
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
= No New Posts since last visit 