Hi fellow (home) barista's,
A newbie to the site logging in after lurking for a long time. I hope this excellent forum can help me?
For some time now (weeks) I wasn't"t able to produce a good shot. All of the shots were 8 second gushers. I tried changing many variables, but experience massive side channeling every time.

My setup now is:
Expobar Leva (recently serviced and adjusted to 9 bar, 93 degrees C)
Fiorenzato T80 grinder (burrs with less than 5kg beans grinded with them)
Torr 58,55mm sharp edge tamper
VST 20gram basket

My routine consists of weighing every dose, aim for a 1:2 brew ratio in roughly 25-30 seconds, distributing by tapping side of PF, then tap on counter (like Matt Berger does), tamp evenly and avoid hitting the PF after tamping to not cause cracks in the puck. After tamping with the new tamper my puck looks immaculate. I make sure to not remove the tamper too quickly and avoid lifting the puck with a vacuum.

The beans I use ae roasted on July 11th, frozen a couple of days after (immediately after receiving) and taken out of the freezer 3 days ago.

After every shot, the puck shows heavy channeling on the sides. The surface of the shower screen is clearly visible.


The shower screen shows quite some grounds after the shot.


I dosed down to 19grams, but this didn't help at all. Same channeling, same residu on shower screen. I didn't dose down any further, since I've heard that yo need to stay maximum + or - 1 gram of the VST specific dose for that basket. Is that correct?

To clarify: i was able to pull decent shots in the past, but for some reason it doesn't work for me anymore lately.

Could someone offer some guidance please? Is it all a matter of beans perhaps?

Thanks a lot!

Have you pulled the shot with a naked portafilter and seen channeling? Examining the puck does not tell you that you have side channeling. The puck will expand and contract and seeing gaps on the sides like that means nothing. You need a naked portafilter to really see what's going on.

Hi ! When did you started to note that "channeling"? after your machine service ? after the new basket/tamper ?

Have you tried grind finner ?

bye!

I would second the suggestion to grind finer and reevaluate. Plus, I wouldn't examine the puck itself if I had concerns about channeling, unless I saw it on a bottomless portafilter.

Thanks for the comments!

I do have a naked PF and saw spritzers all over the place. That happened with an IMS basket and standard Cafelat 58mm tamper as well.
Before and after the service job.

I'll make a video from a shot with the naked PF and link to it in a follow up post.
Regarding grind size: what I did was locate the zero point of my grinder (just next to where burrs just touch, I believe) and adjusted the burrs just about 5mm on the scale from that point. Fairly close to where the burrs touch. I'm reluctant to grind any finer in fear of ruining my burrs.
Or can you actually hear it pretty well if the burrs are too close?

thanks!

Hi Leon,

Glad you posted! One of our baristas was having this channeling issue, and I see it in our beginner classes a lot. After settling/distributing by way of palm tapping, be gentle with any subsequent bangs on the counter. I coach my baristas to only do vertical collapses on the fork of the grinder itself. And lastly, make sure it's going straight up-and-down with no forward/angled momentum. Other than that, everything you're doing sounds right. Hope that helps a little - good luck!

I have seen plenty of trouble from people trying to replicate Perger's distribution method. If its not done right you will get cracks inside the puck almost every shot, I personally feel any hitting of the portafilter from the side is a risky method. You might want to try WDT and see where that gets you.

Auburn Lion wrote: I'm reluctant to grind any finer in fear of ruining my burrs.

No need to worry about that, burrs when touching don't contact their cutting surfaces, just flat smooth metal. You won't ruin them by going finer. I'd also say go finer and try out this method that's been posted around here:

http://www.youtube.com/watch?v=0q-SIs5spnM

Basically, grind into a paper cup, shake/swirl a bit, then dose a little carefully to start, at about half full dump the rest in. If you still have problems I would say your grinder may need a deep cleaning by taking it apart, brushing out all the old coffee and start again. This has happened to me from time to time with certain grinders.

You may know, but just in case, I would suggest to make it a habit to never adjust the grinder finer unless the grinder is empty and motor is running, unless the adjustment amount is very small.

EspressoForge wrote:You may know, but just in case, I would suggest to make it a habit to never adjust the grinder finer unless the grinder is empty and motor is running, unless the adjustment amount is very small.

Thanks for the tip. This one I don't quite get. Do I understand correctly that small adjustments are okay, just no big steps? (Which I wouldn't do. Just 1-2 clicks)

If you single dose, you can just make it a habit to never adjust when going finer. If you have a hopper full, I'd just make small adjustments (not exactly sure how large a "click" on your grinder is....1s or 5-6s adjustment? etc).

Alternative is to start grinding a shot and just adjust right away, you have a bit of a blend of particle sizes, but for a single shot it's probably fine.