Compak K3 single dosing possible?

Grinders are one of the keys to exceptional espresso. Discuss them here.

#1: Post by bandoneon » Jul 12, 2019, 9:14 am

Hi all - first time poster, long time reader, looking for some advice from the experts here.

I just bought a "Compak K3 touch advanced V2" to replace an older K3 (not advanced) that I owned for many years. I'm having some trouble with this new grinder: grinding seems to take forever, at least one full minute for 11 grams, with sometimes no coffee coming out at all. I did the same type of grinding with my old K3, same fineness (for the same espresso machine, La Pavoni pro), and even though I never timed it I can't remember it taking so long.

I mentioned this to the seller and showed them a video, and they are telling me that this happens due to the single dosing (the hopper starts empty, I weigh 11 grams of beans and put only that amount in the grinder). According to them, these grinders aren't meant to work like this, as they need some pressure from extra coffee beans on top of the dose being ground.

This seems weird to me, as I used my old K3 in exactly this way for about 10 years, always single dosing either 7 or 11 grams.

Am I wrong, and is single dosing in the K3 not possible (so was I just lucky with my older K3) ? Is it normal that I need more than one minute to grind 11 grams of coffee ?

Would greatly appreciate some advice, thanks all!


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#2: Post by truemagellen » Jul 12, 2019, 11:01 am

Did you buy it new or used?

If used:

1) are the burrs at end of life and worn out?

2) have the burrs and burr holders been cleaned since you bought it?

3) are the burrs aligned? it is possible they were removed then reinserted and not aligned properly so it doesn't grind effectively

As for single dosing on these you will get a better grind if you put a plunger of some sort on top of the beans to help feed it but that would only lead to a minor change in grinding time, seconds.


#3: Post by bandoneon » Jul 12, 2019, 11:33 am

I forgot to mention that - the machine is brand new!
I did notice on my old K3 that the last few beans took a little while longer to grind, but indeed, it was a matter of seconds. Over a minute for 11 grams still seems like an awful lot of time to me...

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#4: Post by truemagellen » Jul 12, 2019, 12:03 pm

sounds like it is taking way to long and not sure what could be wrong.

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#5: Post by GC7 » Jul 12, 2019, 12:58 pm

I owned a K3 touch for years before I upgraded to a K10 probably 6-7 years ago.

I single dosed exclusively and never had any problem with slow grinding even with very fine grinds. I used a brush and pulsed a couple of times to get all the coffee but I was very pleased with the grind quality and the workflow timing.

Something seems amiss with your V2


#6: Post by DrugOfChoice » Jul 13, 2019, 1:00 pm

I also have an older K3 that I use for single dosing with no problem. Sounds like there is something wrong with your V2. I can't imagine what kind of change they might have made that would make the K3 so unsuitable for single-dosing. My impression is that it's basically the same grinder with the timer knob on the front.

By the way, I get (I think) very little retention with my K3. At the end of each grind I pulse the grinder and brush out the chute, and I get exactly the same weight in and out. At the beginning of each grind, there is about .5g of coffee that comes out immediately, then a brief pause in the flow, and then it flows continuously after that. So my guess is that the initial burst is additional retention. If so, that's acceptably small to me.