About a year ago, I diagnosed my Robur-E as having defective burrs. I replaced them and the quality has been amazing until about a month ago when like falling off a cliff, I couldn't dial in a shot. I broke out my refractometer and just like a year ago, all of my shots are underextracting again. I happened to have a decent set of burrs (I bought two sets of burrs a year ago) and so I swapped them last night and now the grinder is back! My question is how do I know if the grinder is causing premature wear or if the burrs are the culprit? Has anyone heard of a grinder causing burr wear?

I can attest that the burrs never touched during grinding and I've taken very good care of the grinder.

Have you done a visual inspection of the burrs or swapped them back to verify it's the burrs?

Have you inspected the burrs? They may not be leveled if the are flat burrs.

Bluecold wrote:Have you done a visual inspection of the burrs or swapped them back to verify it's the burrs?

I haven't done that yet but when I removed the older set, the burrs were so dull, I could run my finger across the blades and not get a scratch. I can certainly put the older set back in. The other finding was the older set took almost twice as long to grind 20 Gm as the new set. (Over 6 seconds vs. around 3+ for the new burrs)

How many rocks did you run through the grinder?

Lol!! I don't know if that's a joke but none. Up until last week, I was exclusively single dosing which meant weighing every single shot' beans in my OE dosing tray so I would have seen anything that wasn't a bean.

mitch236 wrote:I haven't done that yet but when I removed the older set, the burrs were so dull, I could run my finger across the blades and not get a scratch. I can certainly put the older set back in. The other finding was the older set took almost twice as long to grind 20 Gm as the new set. (Over 6 seconds vs. around 3+ for the new burrs)

Well that certainly points to the burrs being worn. If the only things that touches the grind surface are coffee beans, this is strange indeed as they are supposed to last hundreds of kilograms. Unless you drink as much coffee in a day as I do in a month.

I'd contact Mazzer for an explanation. Maybe they forgot to harden your burrs for some odd reason.

Burner0000 wrote:Have you inspected the burrs? They may not be leveled if the are flat burrs.

It's a Robur - massive conical grinder.

Mitch - You would do all a big favor if you could take a pic of the old/new burrs in question.

Misalignment? I can't think of anything else that could cause this.