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Thread: Large Conical Grinder Users Group...

  1. #301
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    Quote Originally Posted by LeroyC View Post
    I wonder why the Robur has a bad name then. I havenít really looked into it, but Iíve definitely heard that itís out of favour amongst many professionals.
    A few reasons. Background: I was lucky enough to do some testing in a medical grade stainless steel workshop for a couple of days. The laser refractometer showed quite plainly the differences between a number of grinders and their limiting factors in terms of extraction ratio. Rapidly sieving their grinds (about 30 seconds per dose using that gear) instantly removed most of the differences.

    Firstly, large conicals have a pronounced "twin peak" in terms of particle spread. The first peak contains a lot of fines relatively to flat burr grinders. Italians seem to love that as it slows the flow down*, guys like me reckon it fouls the flow up and tends to bitterness. This can be corrected via the roast or later in the process. Correcting via the roast implies roasting darker and losing some regional characteristics (sound like Italian coffee to anyone?). Any barista worth his salt can also correct for bitterness, however the resulting extraction ratio will always be lower. That can be sieved out, however then there is a battle between oxidation and even particle spread. My take: avoid the excess fines in the first place (... enter a Mahlkonig Vario with incredibly long lasting ceramic burrs into my home setup).

    Secondly, Robur's waste a lot of coffee (see slides below). Alternatively, enjoy the taste of stale.

    Thirdly the burrs take a few kilo to run in (shows they are made of crap steel) and the particle spread is completely useless by about 80 Kgs. Even wattgn's earlier posts in this thread noticed that changing his secondhand Robur for a new one made a huge difference. Wonder why? (burrs again). Needless to say, using aftermarket burrs could sort that issue out - and that is a very healthy market.

    So, ignoring the newer wave of grinders altogether, guys like me prefer a Major or any other traditional flat burr grinder to the traditional conicals like the Robur.

    For those that want another opinion:

    https://www.home-barista.com/tips/be...it-t27968.html
    In 2013 Kaminsky 40:05 starts talking about fines. From 45:20 "...(robur)... basically designed with a different market in mind" he analyses why the Robur predetermines your shot and limits your extraction ratio to around 20%. From 55:55 he actually goes through the economics of the Robur. Conspiracy theorists note: about 20 minutes of video has then been edited out. The slides on Ben Kaminsky - NRF2013 VIDEO - Nordic Barista Cup from no39 onward show you the original powerpoint of the content.

    I could post a lot of other links, however after the Kaminsky one had been severely edited, I do not have the time to recheck all the others. David Walsh (http://www.tampertantrum.com/tamper-...x-david-walsh/) is worth a look if it still works - or google it under the title "Tamper Tantrum Live, Presentation Number Six David Walsh : Tamper Tantrum". He goes into even particle spread via wet grinding.

    TampIt
    PS: Ex Robur and Major owner - in that order.
    * The old gravel / sand / "mixture of both" in a bucket and "see the flow" is often used to show how desirable a wide particle spread is. My take - grind evenly and make it fine enough (halfway between Turkish and espresso is close) to give the flow you actually want. Most traditional conical grinders cannot achieve a grind that fine without humongous levels of unwanted fines so the shot goes really, really bitter - and too many CS'r's do not realise it is a grinder limitation, not directly a "quality of shot" issue.
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  2. #302
    Senior Member ozscott's Avatar
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    Having tasted shots from Super Jolly grinders in Cafes and at home versus Robur my preference is SJ. More chocolate notes from coffee and an honest taste. There was a big comparo in the US going back more than 10 years ago now and blind tasting had the SJ ahead of Robur. Having said that in SJ the speed isn't there for busy Cafes hence Major or Robur in Mazzer line.

    Cheers

  3. #303
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    TampIt, thanks for the post.

    I can't really agree that Conical is inherently flawed or limited though. True, on paper the flats are more desired due to its narrower particle distribution. But in my experience, the taste advantage if any is quite subtle to most people. There are reasons why Conical was popular before this wave of flat trend.

    One closest example is the Monolith grinders that can come in two different burrs config (flat vs conical). Many tried to compare them, and all had struggled to pick a winner. My take on that is - if minute taste difference or highest extraction yield % are the sole judging criteria we're really looking into the wrong place (assuming the alignment is fine).

    I have a refractometer, have used sifter (Kruve) and do have access to laser refractometer (very tedious using it but I had thrown in a couple samples). I also have owned a ridiculous list of grinders in the past 5 years in this crazy hobby..it's crazy but here goes...Mazzer Mini, Super Jolly, Major, Robur, Malhkonig K30, Mythos, Lidos, Pharos, Versalab, HG-1, Compak K10, K3, K6, E10, Rosco Mini, Ditting 804, Baratza Vario, Baratza Preciso, Anfim Best, Capresso Infinity, Pavoni PGC, Hario mini, and maybe a couple more that I miss... p/s: if anyone has an EK43 to loan me for a month to add to the list I would appreciate it xD

    Some I had for a 'long' time(>6 months), most for at least a month before I decided to throw it out of the house for user incompatibility reasons...

    All that geeking aside, when it comes down to my taste bud, they all can make great but slightly different shots and play to a different field. I have my preference too but mostly it comes down to the roast that I'm using at the time. Usability and other aspects are more important factors.

    Attached is a refractometer result from a shot this morning using a conical grinder...I had in the past measured a few conicals alongside a flat (Malhkonig k30) but found them to be fairly close..Can't tell them apart by just numbers alone. What I can tell apart is the ground from Conical is usually more 'fluffy' & grainy, grinds faster, and is more forgiving in day-to-day use (no need to keep chasing the right grind setting as the roast ages).
    Last edited by samuellaw178; 9th October 2017 at 09:19 AM.
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  4. #304
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    Quote Originally Posted by samuellaw178 View Post
    TampIt, thanks for the post.

    I can't really agree that Conical is inherently flawed or limited though. True, on paper the flats are more desired due to its narrower particle distribution. But in my experience, the taste advantage if any is quite subtle to most people. There are reasons why Conical was popular before this wave of flat trend.

    One closest example is the Monolith grinders that can come in two different burrs config (flat vs conical). Many tried to compare them, and all had struggled to pick a winner. My take on that is - if minute taste difference or highest extraction yield % are the sole judging criteria we're really looking into the wrong place (assuming the alignment is fine).

    I have a refractometer, have used sifter (Kruve) and do have access to laser refractometer (very tedious using it but I had thrown in a couple samples). I also have owned a ridiculous list of grinders in the past 5 years in this crazy hobby..it's crazy but here goes...Mazzer Mini, Super Jolly, Major, Robur, Malhkonig K30, Mythos, Lidos, Pharos, Versalab, HG-1, Compak K10, K3, K6, E10, Rosco Mini, Ditting 804, Baratza Vario, Baratza Preciso, Anfim Best, Capresso Infinity, Pavoni PGC, Hario mini, and maybe a couple more that I miss... p/s: if anyone has an EK43 to loan me for a month to add to the list I would appreciate it xD

    Some I had for a 'long' time(>6 months), most for at least a month before I decided to throw it out of the house for user incompatibility reasons...

    All that geeking aside, when it comes down to my taste bud, they all can make great but slightly different shots and play to a different field. I have my preference too but mostly it comes down to the roast that I'm using at the time. Usability and other aspects are more important factors.

    Attached is a refractometer result from a shot this morning using a conical grinder...I had in the past measured a few conicals alongside a flat (Malhkonig k30) but found them to be fairly close..Can't tell them apart by just numbers alone. What I can tell apart is the ground from Conical is usually more 'fluffy' & grainy, grinds faster, and is more forgiving in day-to-day use (no need to keep chasing the right grind setting as the roast ages).
    Hi Samuel,

    Yes, the reasons you mentioned, fluffy and grainy (and no clumps) are why I bought a pre-loved Robur, loved it in spite of (in retrospect) some heavily used and a bit worn third party burrs (used by the way as they are $100 cheaper than the genuine Mazzer items). The proof is in using one and I could see and appreciate the quality of the output and ended up buying a brand new one in the EM sale for $1000 Ex. GST and have now had it for a few weeks.

    I should also add 'dead quiet' and 'amazingly' quick to the list of obvious attributes of the Robur too. These are all atributes that are both obvious and undeniable before even considering the flavour differences which I generally agree are subtle and I definitely like the flavours in the cup from this machine. I try not to rave on too much about it as flavour is very subjective and hard to nail and depends on YOUR taste buds.

    I really didn't consider the flavour differences, if any, as the top item on my list. I did two comparisons with my M4D, in one no difference, in another I liked the flavour better from the Robur but I realised short of wasting a lot of time and coffee, and doing blind tests, it is hard to really prove differences in flavour, not to mention you optimise the grind for each one, not necessarily to be the same but to give the best cup.

    Finally consistency of grind performance...wow. It is super consistent. I can grind a 250g bag of beans without making an adjustment and small variations in weight due to my volumetric dosing, make only a small difference to pour. While the M4D was great in that area too, this is another level again. I don't know if that is just from being conical burrs (although baristas) think it is but definitely helped by the sheer size and precision of the tolerances in what are very big burrs and associated bearings etc..

    On what TampIT said...

    It is rubbish about grind retention, yes it is there but no more so than on the M4D or a number of other small commercial or prosumer grinders used by enthusiasts, especially on the doser machine very little really sits in the chute. I definitely don't get any stale shots even the first one in the morning. If you want a machine meticulously clean of the last bean and ground then maybe it isn't the machine for you and there is a market for those types of machines too. IMHO though the Robur scores well in this regard in spite of it's size.

    Finally it is not true about Mazzer burrs being faulty in some way in the Robur as sold by Mazzer. I spoke to more than one tech. and Mazzer themselves say that they are now pre-seasoned. The tech said that the reason that the third party ones are used is solely on price and they in fact don't last as long as the Mazzer burrs which are rated to 700 or 800 kgs.

    If you choose to believe Mazzer sell faulty poor quality burrs to all their customers for their use which if TampIT is to be believed could be less than a fortnight of effective use before becoming worn and substandard then possibly ask yourself if this really appeals to your common sense... and why this same complaint would only relate to their flagship machine and not all Mazzer grinders. There was an episode in 2012 when they did produce some sub-standard burrs but this was fixed quite quickly. It seems the notion persists.

    The grinder is also built well (understatement) unlike many other prosumer grinders especially the ones built for zero retention which seems to result in a delicate burr assembly, the vario and others. To some extent you get what you pay for too. The Versalab M3 is an exotic grinder built for zero retention which also applies to your bank account after buying one but no doubt is an excellent.

    In the end if you have a grinder you like, really like then keep it...and buy another one when the wife isn't looking if you are still curious. I'm not one-eyed on conicals really but this one impressed so much I had to have it but I am still curious about large flat burr grinders like the Major, I'm sure that they are great too.

    You can't go wrong with the Robur (aside from it is BIG and it can be expensive). I would highly recommend a home user, even a new one to try out one of these Roburs. They last such a long time that even ex-cafe ones (with fresh Mazzer burrs) are a good buy if you can get it past your wife or significant other (my wife hates coffee so she must love me).
    Last edited by wattgn; 9th October 2017 at 12:10 PM.
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  5. #305
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    Just another interesting comment on another thread that explains what I could not but observed...

    On my NEW Robur, the zero point where the burrs touch is past zero but towards nine.

    I set it to 2.5 which was my guess based on the used Robur I bought.

    I wasted a lot of coffee as at 2.5 the grind rate was very slow and it came out powder. The amazing thing though it was powder and still very slow at 4 or so and the final set point was near 7.5 to get my pour which is where it is now. This behaviour is way different to the flat burr grinder M4D I owned.

    Here is a technical explanation from the Titan grinder thread...

    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.
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  6. #306
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    Quote Originally Posted by ozscott View Post
    Having tasted shots from Super Jolly grinders in Cafes and at home versus Robur my preference is SJ. More chocolate notes from coffee and an honest taste. There was a big comparo in the US going back more than 10 years ago now and blind tasting had the SJ ahead of Robur. Having said that in SJ the speed isn't there for busy Cafes hence Major or Robur in Mazzer line.

    Cheers
    Hi ozscott:

    The differences as Samuel noted in flavours can be quite subtle:

    Here is the summary from the Titan project. Flavour is subjective and also getting the grind the best for each grinder isn't easy. Flavour as discussed isn't the only reason conicals are well respected...

    The Fight

    I was expecting another boring Italian soccer match, but instead it went back and forth. The Jolly is different, period. In successive rounds, it produced "interesting," identical, far worse, and far better shots when compared to the as always steady tasting Robur. I found while the pours and packing are fairly consistent, the taste of this grinder, with a sensitively balanced blend, is all over the place.

    In the first 13.5 gram round, its shot tasted like it had been roasted a few notches darker, with a lot more caramel, and a lot less fruit. The crema was thinner and browner as well. My half point taste edge to the Robur was subjective -- the shots were different, and others would have the preference the other way around.

    In the second 13.5 round the shots were nigh indistinguishable, except for a nicer tiger flecking on the Jolly's.

    In the first 16.5 round, the Jolly's taste was over-aggressive, and it lost by 4 points.

    In the final round 16.5 gram round, the same aggressive taste was coupled to improved sweetness and a more persistent crema, which enhanced the shot enough to give it the taste edge. This time it won by 6 points, the biggest single round score of any grinder over the Robur.

    Final score: 2 rounds each, Robur wins by 1.5 points.
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  7. #307
    Senior Member chopinhauer's Avatar
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    Quote Originally Posted by wattgn View Post
    To some extent you get what you pay for too. The Versalab M3 is an exotic grinder built for zero retention which also applies to your bank account after buying one but no doubt is an excellent..
    Agreed and touche. I get zero retention in both your senses from my Monolith Conical (ridiculously expensive after currency conversion, shipping and tax). But for real zero retention in the bank balance sense, at least, check out the Titus from Frank Durra, which begins at around $AUS7,000 before shipping and taxes. And you can easily double that price with customisations.
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  8. #308
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    Quote Originally Posted by chopinhauer View Post
    Agreed and touche. I get zero retention in both your senses from my Monolith Conical (ridiculously expensive after currency conversion, shipping and tax). But for real zero retention in the bank balance sense, at least, check out the Titus from Frank Durra, which begins at around $AUS7,000 before shipping and taxes. And you can easily double that price with customisations.
    Chopinhauer,

    yes sounds good. Coffee nutters like us (some with more money than others) create a market for some interesting but often scandalously expensive machines but value and also cost are all relative to what you want and can afford. The Robur, for me, was just affordable. After I got the used one I took a punt and made a bid on gumtree for one, offering $1500 with GST and shipping but $1800 was the best that they could do then the sale came along and it was an offer too good to refuse and the used one got sold on gumtree for what I paid for it.

  9. #309
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    Quote Originally Posted by chopinhauer View Post
    Agreed and touche. I get zero retention in both your senses from my Monolith Conical (ridiculously expensive after currency conversion, shipping and tax). But for real zero retention in the bank balance sense, at least, check out the Titus from Frank Durra, which begins at around $AUS7,000 before shipping and taxes. And you can easily double that price with customisations.
    Yes, looking at the Monolith ( I believe this was the same one as in 2001 A Space Odyssey). Seriously it is the sort of finely engineered home enthusiast type machine, ridiculously and laughably over engineered.... (all good in other words) but with adaptations making it more suitable for single dosing and low rate usage. It maintains though the fine principles of conicals that make them so effective and to boot achieves an even lower RPM of 250 versus 420 RPM for the Robur.

    I have also seen a few other high end conicals along the same lines of design. I have nothing against them either except I can't afford one. This is where those with shallow pockets can pick up a damned nice Robur ex-cafe. The one I picked up was $650 but did (in hindsight) need a new set of burrs. In a cafe, a busy one, the burrs on a Robur need replacing every three months. Shocking really. 30 years of normal use in a household probably.

    The used Robur I had, did a small jolt turning it on, absent in the new one and probably a design enhancement. It was 2010 model. It had the round tray (a good design actually as it could slide in and out to suit using long slots around the rubber feet. Some cosmetic damage around the front where staff bang the machine with the portafilter. The adjustment ring at the top needed polish and the Hopper showed some very minor deterioration.

    I say to people well, 'put that in your pipe and smoke it', if they wonder why an ex-cafe machine is a good deal to consdier. After processing between 5 and 15 tonnes of beans, that is 250,000 to 750,000 shots of coffee and it still runs quietly as a new one and with new burrs would perform like a new machine. Not a bad deal if you can get one at the right price. Even adding $250 for Mazzer burrs it is still a good deal and the burrs in home use would last decades.

    At even say 4 seconds per shot (and it is closer to 3 seconds for 20 gram double) that is 200 seconds per kg of coffee and say 10kg in a busy day is 2000 seconds which is a run time of just over 30 minutes per day. This is not a lot for an electric motor and bearing and is why these things last for decades in a cafe setting...easily.

    A nice toy. GNW certificate of approval in the mail for your Monolith...
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