Italmill makes a bunch of different conical burr sets for various grinder and espresso machine companies, but in their trade listings they show standard outer diameters of 38mm, 48mm, 71mm, and 83mm. A few companies say they use 48 mm conical burrs, but Italmill's site shows they tend to be used more for small commercial superautos.

Confusingly, OE currently lists the Lido 2 as having 48 mm conical burrs.

You are correct. They are measuring the OD of the outer burr at the widest point, the collar. You have correctly ID'd the burr set.

http://www.oehandgrinders.com/assets/im ... %20Set.pdf

We have updated our terminology to stay current.

orphanespresso wrote:You are correct. They are measuring the OD of the outer burr at the widest point, the collar. You have correctly ID'd the burr set.

If this is true it is very disappointing and surely against convention?
No one would pay 150 bucks for a hand grinder with the solis (ie. starbucks) burr, knowingly anyway.

I did some further sleuthing. The catch cup for the ROK is said to double as a tamp for their ROK espresso maker. This has a 49mm tamp/portafilter size. So in side shots of the grinder like on the indiegogo main page you can see clearly that this 49mm base is only very slightly narrower in diameter than the burr housing. It looks like there is not enough room for there to be any collar at all, if it is truly a 48mm burr set. But then again, if it were a 38mm burr you would expect the housing to be slightly narrower than that. However further down the campaign page is a diagram showing the internals and a demonstration that the outer burr is quite a lot narrower than the housing. I am very disappointed. Surely this goes against Indiegogo rules?

Edit:
Looks like my post at the top of this page was deleted where I identified the burr is actually the 38mm Solis/ Baratza Maestro burr. So just filling in that information again.
http://www.baratza.com/cgi-bin/commerce ... n&key=6071
Now that we can see it more clearly in the new ceramic photo on the campaign page, you can see it in the video too and it looks identical. I hope that it is just the shared burr design in a larger build, but that is perhaps wishful thinking.

IMAWriter did warn me that they were probably measuring 48mm as the diameter of the burr carrier but I didn't believe him. Looks like he was right.

More reasonable would be to call the mm size to be that of the inner burr on a conic, but Italmil clearly calls this, in the catalog and spec sheets a 48mm, just as they call the burr in the haus/field grind a 38mm (no 5mm collar). The 71mm burr is 71mm OD of the outer burr, etc.
Perhaps as important as size is blade geometry, etc as these burrs are matched to motor size and machine design...after all, they are designed for electric grinders.

orphanespresso wrote: Perhaps as important as size is blade geometry, etc as these burrs are matched to motor size and machine design...after all, they are designed for electric grinders.

From what I have read about that burr set it is not good for espresso. But on the ROK campaign page they are pitching it as an espresso grinder. I wonder if it is something in the Maestro design that prevented the burrs adjusting close enough for espresso and not inherently something in the design of the final section of the burr. I believe this burr is also used in the Graef CM80, a grinder I was contemplating buying in germany as my first electric grinder. It was considered a decent starting point, but nothing more - though it could grind fine enough for espresso.

Edit: I believe it is also the burr in the Breville Smart Grinder. Disappointing!

Hi Roland,

I'm not sure where you've got the impression that the smaller burr are not good for espresso. I can vouch it works well, provided the adjustment system & alignment are good. Most of the unsuitable examples you quoted are either : i) Not rigid grind adjustment ii) huge stepped adjustment iii) weak motor not suitable for high duty espresso grinding iv) imprecise alignment v)plastic built v) weak burr mount

I was using a Rosco Mini and Lido 1, both with 38mm conical burrs. Suffice to say they worked really well for espresso.

Yes I understand that, but none of those mentioned hand grinders use this burr set. They use a different one which faired very well in the Titan blind testing thread from a few years ago. To be clear I was not dissing all 38mm burrs, but the Solis one (though very commonplace) has not to my knowledge ever been selected for a hand grinder. I wonder why.

In any case I am in no position to says this is unsuitable for espresso, I am merely provoking the debate. I am disappointed first of all that ROK has been misleading with their information, implying a larger burr was used in their grinder. This in turn implied the ROK was something especially new (aside from its form factor) and made it more appealing than it now seems. (It should be reiterated that this particular burr is commonly referred to in other situations as a 38mm burr. and they clearly state it is 48mm.) Secondly, I am disappointed because I have never seen this burr being used in anything but mass produced value grinders and likewise I have heard no tales of it punching above it's weight like the Lux burrset (in the Lido and Hausgrind etc that you mentioned). I could be wrong in my negative presumptions.

Yes the other mechanical factors you mention do play a massive role in the outcome of a grinder. Perhaps this will make all the difference with this burr. And there are other design features which I find appealing. I for one very much appreciate the geared axle, not just for ergonomic reasons, but because it minimises up and down rocking motion of the axle from your unstable hand as you grind. On some grinders, for example the Lido 2, lifting the handle slightly during a rotation while grinding will close up the burrs even just a tiny bit, for a split second. Also there is even a very slight flexing possible in a 2 bearing axle. We are talking very small amounts, but everything counts. If you remove the lateral motion of the handle swinging round the axle and replace it with a gear that is neutral in terms of its lateral load, you eliminate that problem.

I received a response from the designer.
He seems to confirm that 48mm is an unconventional measurement but one that is authorised by the burr makers, like OrphanEspresso was saying. This all but confirms it is in fact the 38mm Solis / Maestro / Starbucks burr.

He also acknowledged a few comments he had read about the wobble in the video. He assured me this is due to the higher tolerances in the prototype and said that this particular axle has a lot of blemishes which makes it appear to wobble in the video. He assured me the final product will not wobble.

So some good and bad information.

If the rest of the grinder turns out well but you are unhappy with the burrs there are other 38-40mm burrsets that should fit. It is disappointing that they claimed they were 48mm just as it's disappointing to now see OE doing the same.

The manufacturer defines their product. Once you have the drawing then you can decide what you would like to call it but the retailer is pretty much locked into what the actual manufacturer defines as the measurement standard.