That was the question I asked myself one day. Why bother?

My reasoning was, that once the grinds filled in all the dead space, the new grinds should be able to push out the old ones...
Soon after that decision I noticed that nothing is coming out of my Mazzer mini E -A. That is, nothing at all.
So, I removed the hopper, and looked inside - some crashed beans were there. I tried to grind them away, but the beans did not seem to have any inclination to move down into the burrs.

I opened the funnel, and to my amazement saw that the opening was absolutely plastered with the grinds, so that the Mazzer's grill could hardly be seen.



I tried to vacuum them out of there, but they were stacked and cemented together, so that the vacuum cleaner could not do anything at all. It took me some efforts to get the grinds out of there with a small brush.




I clearly saw that the grill was the real culprit. Its function is to de-clump the grinds as they are pushed out, but if do not clean it regularly, the grinds might get stack to it and to each other, and eventually block the exit chute.



Clearly the grill should not be there. Fortunately it can be removed without any efforts. It is not even glued. You just need to remove the funnel, and then pry the grill gently out of its place. That's all.



Now I am just vacuuming my grinder about once a week (a bought a separate adapter for my vacuum cleaner, so that I am not using the same for cleaning car, door mat and the grinder), and it works like a charm.

tonythewonderful wrote:Clearly the grill should not be there.

I agree with your premise that the grill serves no useful purpose in a home environment, but for sake of completeness, I'll offer an explanation for why it's there.

To improve the accuracy of timer-based dosing for doserless grinders, manufacturers add a flap or grill on the chamber exit to create backpressure. So instead of grounds being flung out in random spurts, the coffee is extruded at a measured pace. A home barista may not care that the coffee dose varies by more than a half a gram (since they're probably weighing anyway ), but a cafe owner banging out 100-200 shots a day appreciates the extra precision since it saves them coffee.

Although many years has passed since I owned a mini-e, I do remember that the anti-static grill was a constant annoyance and did not really make alot of sense, as the grinder in itself does not have enough centrifugal force to overcome the barrier.

On some of the bigger models however, it clearly makes more sense, as the back pressure the grid creates, improve the dosing accuracy, reduce the problem with static grinds going everywhere and sticking to the inside of the funnel and in some cases overspraying the poor person standing next to the grinder. On those models I would not recommend it, unless you love to clean up and use alot of time improving on the dreadful dosing.

HB wrote:So instead of grounds being flung out in random spurts, the coffee is extruded at a measured pace.

malling wrote:On some of the bigger models however, it clearly makes more sense

Yes, the problem with mini is that its burrs can chew too few beans at a time (Difference between Mazzer Mini E burrs and Super Jolly burrs?)
and hence a very small amount of the grinds flying out per second. The grill stops to many grinds (instead of de-clumping them), and they block the exit chute, and the flow of new grinds is simply not powerful enough to effectively push old ones out.

I have a K10 and have never once actually cleaned it! I don't really understand the point as I've never used oily beans. I know it has stale coffee in it but I presume that would happen the first day again after cleaning and using it.

I mean assuming the ground coffee on the recently cleaned burrs is again stale the next day!

RyanJE wrote:I've never used oily beans

Neither have I
I am using only coffee that I roast myself, and it is never dark enough to be oily.

It takes my mini about 20 sec to chew through 14g of beans (I always load only one dose at a time, for folks who store beans in hoppers it might be faster)
Your K10 probably does the job in 3 sec or so? It means that K10 creates a much more powerful stream of grinds that effectively push old ones out.

RyanJE wrote:I have a K10 and have never once actually cleaned it!

How long have you been using it?

For the last couple of months I just vacuum the mess around it once a week, otherwise it gets way too messy, and while doing so, vacuum the grinds out the grinder through the exit chute and the opening.
This seems to be working fine, and I am kinda hoping to stop opening my mini and cleaning inside with a brush altogether.

tonythewonderful wrote:Neither have I
I am using only coffee that I roast myself, and it is never dark enough to be oily.

It takes my mini about 20 sec to chew through 14g of beans (I always load only one dose at a time, for folks who store beans in hoppers it might be faster)
Your K10 probably does the job in 3 sec or so? It means that K10 creates a much more powerful stream of grinds that effectively push old ones out.


How long have you been using it?

For the last couple of months I just vacuum the mess around it once a week, otherwise it gets way too messy, and while doing so, vacuum the grinds out the grinder through the exit chute and the opening.
This seems to be working fine, and I am kinda hoping to stop opening my mini and cleaning inside with a brush altogether.

I'm going on about 1.5 years now and have never once removed the burrs or truly "cleaned" it. I just don't really understand the reason for cleaning a grinder that's in perfect working order. Seriously, after a cleaning aren't we then just grinding more coffee that's going to stale in short order? That said, I brush out the doser after every use.

I worry more about taking it apart and doing more damage than good for no real benefit..

Now, if I bought something used that needed cleaning up, whole different story.

RyanJE wrote:I just don't really understand the reason for cleaning a grinder that's in perfect working order.

Given enough time the grinds will go rancid, some breaking off entering the dose and some getting harder to remove and jamming up the areas they sit: the screws and threads - it's pre-emptive maintenance so you can dismantle it later. If the grinds eventually work themselves under the burrs it may affect alignment, too.

Has this all been proven or demonstrated somewhere on grinders properly and consistently used?

What's different about these grinds than ones I ground 5 days ago? 10, 15, 20?

Doesn't this assume that none of the retained grinds are ever replaced by newly ground coffee? Personally, I'd be more than happy to tear down my grinder and clean it if I was convinced it adds value, but I don't get it.

When I get more grinds out than I put in, yes I assume some of the retention has been added to my dose.
When I open my grinder because the adjustment gets tight after a month or so and see what appears to be fines behaving as a smelly gel/solid, yes I assume they have gone rancid.
Sorry, I don't have a RCT to demonstrate this. I don't have a certificate to prove that I've been using my grinder properly.