channeling

[zak42]

Picking up from the pride page post, here's a shot which doesn't seem to be suffering from chanelling (although there are those 2 pockets which never came through)





but it ran for 45 seconds, making the grind coarser for a 25 second shot, always seems to get me back in to channelling land (and always at the back).





Is this a distribution thing, an unlevel tamp ? any pointers ? Any related to my flow profile post, the cone never seems to fill out.

[zak42]

Well, i just burned through a pile of beans, and learnt a lot, a good investment. I payed close attention to the grind / dose / tamp aspects.

I have a Mazzer Mini E grinder, and what i noticed was that i would double tap the button to get a double dose, leave the portfilter on the PF rest and go start aranging the milk, i would then come back push the PF up against the button to run the grinder long enough to top up enough grind in the basket. As you can see from the photo, the combination of the round PF handle and the smaller basket size means that the PF is not level and its grinding into the front side of the basket.



I went back and looked at my Gaggia PF and the combination of the 58mm basket and a larger square handle meant that doing the above procudure would grind into the center of the basket, and that the PF is level.

If i hold the S1 PF level and in position so that the grinds fall in the center of the basket, then activate the grinder with my finger, i get results much closer to what i was expecting, the flow profile & cone size is also much more like what i was expecting.



After all that i also noticed that regardless of what i do, when the shot starts it always starts at the back of the basket and sweeps towards the front, is this common ?

[Barry]

I use a Mazzer Mini and have never had issues with channeling. I always overfill the basket with loose grounds, then level the grounds, however, I don't really use a sweeping motion so much as a combination of sweeping and pressing the grounds to level. This creates a tamped puck that is almost perfectly level with the baskets retention groove. My pour tends to start at both the back and front and then come together. You may want to check to make certain your counter is perfectly level. When you remove the brass diffuser, you can see that the water actually enters the top of the diffuser to one side of the screw hole that holds the diffuser and screens in place.

[padillatim]

I removed the fork from the MM so that I could rotate the PF more. I was seeing a similar issue, with less distribution in the back and overextraction from that side of the basket. I rotate the basket as it fills and then level using stockfleths and a sweep. I think distribution is king... if it is good, the tamp takes care of itself.