Poor Grinder Burr Manufacturer QC

#1: Post by **shadowfax** » July 28th, 2009, 7:23 pm

I took a lunch break and visited my friend Paul today, carrying along my Nino burrs to show him. He'd agreed that we'd pull his Robur burrs and compare/contrast them to the Nino set. That was something of a revelation in 2 ways: first, the Robur (which is running great, shotwise) had a surprising amount of apparent damage, similar to Chris' photos or maybe even worse. Second, I can't see any meaningful differences in the Robur and the Nino burr sets. It seems as though the major difference is that the Robur top burr is milled from a larger steel cylinder and mounted by 3 holes rather than 4. I could literally buy a set of Robur burrs and use its bottom burr with my current (unscathed) Nino top burr (!).

Paul's got some fantastic photography gear, a Nikon D100 and a slick macro lens. We took some nice photos of the two burr sets. Check this out:

Yet better photo of my Nino bottom burr... (Flickr link: 1, 2)

Robur E's Bottom Burr for comparison (Flickr link)

Robur and Nino bottom burrs facing each other at the base--Robur burr is on top here (Flickr link)

Robur and Nino bottom burrs facing each other at the tops--Nino burr is on top here (Flickr link)

Robur and Nino top burrs facing each other at the bottoms--Nino on top (Flickr link)

Robur and Nino top burrs facing each other at the tops--Nino on top again (Flickr link)

Robur and Nino burrs stacked on top of each other--Nino on top (Flickr link)

So... I'm thinking the Robur isn't that special, and that calling them "71 mm burrs" in contrast to "the other 68mm conicals" is a bit mistaken on our part/disingenuous on Mazzer's. Which isn't to say there aren't some distinct differences (beyond the mounting systems of the top burr): The Robur's finest cutting face (the shiny part) seems "wavier" and smoother overall. Also, its crushing knobs on the upper and lower burr are thinner, though this seems purely superficial. Did you guys know any of this? It's crazy, I never checked with my own Robur because it just looked bigger to me when looking at the two in their respective grinders. Turns out that was just skewed perspective...

Anyway, Paul and I both agreed that my bottom burr looked somewhat more damaged, particularly with some notches along the lower ring, but that both burr sets looked rather sub-par on their bottom burrs. Have we both taken minor stones? Is this what these things look like from the factory? Are they designed to deteriorate in this way?

Finally, it sounds like most of the signs are pointing to that I just sucked at dialing in 2 blends last week and made a big deal of it when I saw the crappy looking burrs in my grind chamber. Damn. Well, we'll see. I got some coffee this morning, and the Notchy Robur E vs. Notchy Nino test is on for Saturday. I'm also going to ask Jon to pull his burrs and see how bad they look. If they look better, I may try to get him to bring my old Robur back for the fun instead, maybe a 3-way elimination test or something.

Moderator note: topic split from the thread Elektra Nino Grinds Through Rock; Request For Help From K10/M7KR Owners; please refer to the original thread for context.

#2: Post by **another_jim** » July 28th, 2009, 8:27 pm

Interesting. It almost looks like Mazzer designed the Robur for the standard 68, then made their burr a bit faster grinding (see the distinctly steeper/more vertical slope on the burrs) and upped the motor HP. No wonder all the 68s were toss ups with the Robur when I did the taste comparisons.

July 28th, 2009, 9:04 pm

Indeed, the Robur burrs above do have a more aggressive cut. It's hard for me to gauge visually how they compare to Chris' replacement burrs as discussed here, where his replacement burrs had noticeably different fine cutting surface shape AND more aggressive cutting angle. I'm wondering how big of a deal that is... Judging by Chris' experience, I imagine it might be fairly subtle. Still, it's certainly a mystery why they chose such a powerful motor for the beast, beyond that it's awesome and quiet.

#4: Post by **michaelbenis** » July 29th, 2009, 2:40 pm

A very interesting thread, Nicholas (and great photos).

Glad to hear you won't be needing new burrs and all kudos to you for stating your plain conclusion without fuss.

On the whole I have surprised myself with how quickly I can dial the Nino in and then all of a sudden I take ages getting it right - which is what happened this week (with no obvious weather changes), tightening the grind up quite astonishingly on a new light-roast Nicaraguan.

Cheers

Mike

#5: Post by **another_jim** » July 29th, 2009, 3:58 pm

I remember the similar discussion on initial burr quality came up when all the old Starbucks grinders were being sold by Tagex, and people got replacement burrs that were all over the map.

It's clear that most common burrs, including these 68mm conicals, are multiply sourced. The different sets are "plug-compatible," but have slightly different burr angles, and, most importantly, they are not all that well ground or polished. That means dings, roughness, spots, etc on brand new burrs, and maybe as much as 20 or 30 pounds worth of beans as the final polishing agent before their performance becomes completely consistent. I thought my Compak settled in after 5 to 10 pounds, but I never examined closely examined the burrs week after week.

#6: Post by **malachi** » July 29th, 2009, 5:01 pm

There was a period of time (for example) around the Tagex liquidation of Super Jollys, where more than 50% of Mazzer burrsets we were seeing had tons of loose metal filings all over the cut edges. If you installed these with a good brushing to remove the filings the burrs would dull VERY quickly (and in some cases would chip the first time you turned the grinder on). After a lot of whining, we got back channel that burrsets were coming from at least 3 different suppliers and at least 1 of them was overwhelmed by demand and doing a crap job of finishing.

July 29th, 2009, 5:06 pm

Jim/Chris, have you ever heard of a study of burr defects and their impact on grind quality?

I've been pulling shots of this graciously donated Brazil SO from 49th Parallel today, and the Nino seems back in the zone after jumping to my triple basket, 18g, and 201F pulls. The last shot I had was mellow and sweet, and somewhat more complex than last week's messes... So I'm getting even more convinced that my ugly bottom burr is not associated with a recent rock or the bad shots I made all last week, suggesting perhaps that I need to work on my barista skills with respect to parameter exploration.

My 'problem' aside, taking a closer look at these burr sets has really been disappointing. It's one thing to be like this on a $30 set of Super Jolly burrs to be rather rough, but these 68mm conical burrs play in the $200 range from what I have seen. Previously I'd understood burr seasoning as dulling overly sharp burrs into performing consistently and as needed for espresso. Now I'm beginning to think it's more a case of wearing down notches and dangly edges of metal from rough cuts that should have been ground off in the first place, which would explain the variation in peoples' experience with seasoning. How much could something like that have skewed, say, reviewers' impressions in the TGP?

What a shame Mahlkönig can't get over their flat burr thing; I bet they make way better burrs than the Italians.

#8: Post by **JonR10** » July 29th, 2009, 5:31 pm

shadowfax wrote:What a shame Mahlkönig can't get over their flat burr thing; I bet they make way better burrs than the Italians.

From my experience replacing the K30 vario mills I'll say "not much better, if at all". The K30 mills had obvious machining burrs (think "hanging chads"). I did not grind, but I did use a very fine file to remove the obvious flaws and the overly sharp edges at the spots machined out for the screws.

The finishing process for freshly finished metal parts in a machine shop is called "de-burring". In my work we disqualify vendors who do a poor job of finishing the parts after they come off the machines, so it's a surprise to me seeing such poor finishing work on these "precision" parts.

#9: Post by **another_jim** » July 29th, 2009, 5:41 pm

shadowfax wrote:Jim/Chris, have you ever heard of a study of burr defects and their impact on grind quality?'... How much could something like that have skewed, say, reviewers' impressions in the TGP?

Sadly, I think you and a few others are the glorious pioneers on this snafu. A cafe would put through 20 to 30 pounds of coffee through a grinder in a week, so the burrs would be seasoned before anyone really noticed anything. We would be spending half a year if a grinder needed that much coffee to season. By that time the thing would have been out of the window.

In the TGP, the early reports favored the Jolly, especially when used with those very nicely finished duranium burrs, and strongly panned the Kony. By the time I got them, the Jolly remained a solid grinder, but all the Titans had a distinct edge over it.

I'm the only one who did all the grinders side by side. I got them last, discarded all my initial tests, and held them for an unconscionably long time before I was happy with what I was tasting. I assumed this was my problem; I was going through a depression and figured that my taste buds weren't functioning right, and that's why I couldn't get any clear results from the comparisons. But the grinders could have been changing all the while as they broke in. It's just not something that even occurred to me as a possible source of problems.

#10: Post by **malachi** » July 29th, 2009, 6:24 pm

shadowfax wrote:Jim/Chris, have you ever heard of a study of burr defects and their impact on grind quality?

Sorry - we just used to always visually inspect new burrsets and return the defective ones, so I don't have data on what grind would be like. And now I always "clean up" new burrsets on arrival (unless the defects are so bad that I send them back).