I would need advice on the status of the burrs of my Max. It can't grind for espresso. I have taken some images of the burrs, you can find the series up on my web site. Will publish them here too, soon, but for now just please have a look at
http://www.digitalakuten.com/coffee/maxburrs/

I think I have established beyond much doubt that the flat burrs need to be changed. Looking at the detail image of the top burrs, the edges are really worn.

But how is the state of the conical burrs? To me, they look worn too. What do you think? Sorry about the bad image quality regarding the bottom conical burrs... will try getting a better shot of them later on.

Also, when looking at and feeling the top screw, it looks like the motor axis is not perfectly centered. Is this OK for a Max, will it center itself when there is enough of coffee inside the grind chamber?
If not, is there something to do about that eccentricity?

OK, as promised, here are the images. Now rescaled and cropped to fit home-barista better. Detail and overview images are from the same original image, that's as close as I can get with my optics.
Again, sorry for the bad image quality regarding the bottom conical burrs... here they are:



Top conical burrs, detail image follows in the next message:

Top conical burrs, detail:


Bottom flat burrs, a bit more detail here, and the worn edges should be visible...


How bad is this eccentricity behaviour, that 's what I worry most about. And do the conical burrs also need change? (If that is possible to say from these images...) I was quite surprised that I couldn't get anything close to an espresso grind from it, this Max must be in rather bad shape.
P.S. The burrs are not clean, I know. Still, I have done quite a lot of cleaning. The grinder was in a rather dirty state when I got it.

The Max uses a hybrid set of burrs; the first conicals act as an auger, breaking the beans into smaller pieces. They have no finishing perimeter like all-conical burrs. Subsequently it would take a long, long time to wear out the Max's conical burrs. T.J. from Cimbali could probably find out the recommended conical to flat burr replacement schedule. For home use, I would say it's "never".

As for the flat burrs, I cannot say if they "look" worn. Do the edges feel sharp or dull? When you say it can't grind for espresso, are you certain the burrs are coming close to touching? A dirty grinder could have gunk clogging the threads giving you the impression that the burrs are meeting final resistance when they're in fact a good distance apart.

That said, if it's a used grinder and there's any doubt about the flat burrs, replace them. You'll not need to do it again for many years.

Thanks for chipping in, Dan.

are you certain the burrs are coming close to touching?

Should have written that, sorry. Yep, I have cleaned the gunk out and turned the setting screw as far as it goes and then some - and I heard the (faint) sound of burrs meeting.
The edges feel dull. They can't shave off anything from the surface of a finger nail, for instance.

the first conicals act as an auger, breaking the beans into smaller pieces. They have no finishing perimeter like all-conical burrs. Subsequently it would take a long, long time to wear out the Max's conical burrs.

Sounds good. The worn corner edges of the top and bottom conical burrs should be OK then, I hope. These burrs don't feel sharp either. They have edges, but those edges either have never been sharp, or have been worn dull.

How about that eccentricity? Is that OK? On my two other grinders (one Minimoka M-203, one Anfim KS Self) it has not been OK - if there is off-center rotation it has always translated into uneven grind.

The conical portion really never needs replaced. Even when new they are not terribly sharp, nor do they need to be. They simply break the beans into large chunks and feed them into the flat burr cutters. You could replace the flat burr portion but even with worn out burrs you should be able to choke a machine unless you have some old coffee.

Well... I'll try to see if that non-centered rotation changes after a good cleaning and with new flat burrs then. The grind that comes out of it right now is somewhere between lungo and moka grind. Old or new coffee is the same.
I will probably change the auto-stop while I am at it, unless that proves to be very problematic. I also have a broken grinder bottom plate/foot to fix (it was broken during transport, so that is why I worry that there might also be something wrong with the rest of the grinder)