Sylvia channeling problems

[WME]

Hi everyone, been lurking around for a while but first time posting, hoping someone can help out.

I've got a rancillio Sylvia and a rocky doserless grinder, both about a year old, was all going fine up until about a month ago when I've started having really bad channeling problems to the point where I can't get a decent shot.
Thinking back it would've started around the same time I pulled the screen off to soak and clean it.

I'm using the same beans (Gesha from freo) similar grind and trying to keep my distribution and tamp as similar as possible to narrow down the cause.

Pulled screen out the other day and gave it a good clean and pulled one really good shot, then the next shot straight after was terrible.

Have just replaced the gasket above the screen with a new one and descaled the machine.

Trying to fault find the problem, have tamped to just below the ridge on the double basket and inserted then removed the basket and I'm left with an imprint of the hex bolt in the puck? I thought that the ridge mark was the right level?

Any ideas welcome as I'm at my wits end trying to get a decent shot, just want to go back to pulling nice shots and enjoying my machine.

Thanks
Jake

[tobeanornottobean]

How do you know it's channeling? Have you tried wdt to help beak up clumps and distribute grinds?

[mrsakata]

I have a silvia as well and have noticed that the hex bolt protrudes far enough to make an impact on the dry puck in a lot of cases. I'm not sure what effect that has in relation to channeling, but my understanding is that it is best to use a dose/basket that doesn't end up with an indent in the dry puck. It shouldn't matter if there is an indent in the wet puck at the end of the shot though. If you are getting an indent in the dry puck, which you can check by putting your portafiler into the group head and taking it out again to look at the puck, I would suggest trying a lower dose - or maybe trying a different basket (e.g. VST). I use a VST 18g basket and dose 17 grams which tends to avoid any imprint from the hex bolt.

[dumiya]

FWIW, I believe channeling is a grinder or bean problem. Rockies do clump so does the M4D. If the clumps are loose they break up easily so sometimes they are very tight. Try to grind a shot, get a meat skewer and break up the clumps or empty the grinds into a container and break up the clumps, put them back into the basket, tamp. The hex head on the filter should just touch the top of the tamped grinds. Then extract. You will loose some flavor because of the time stirring up the grinds. But try. This may help eliminate Silvia from the problem?

Addition: if the timing is right with channeling then the grind is too fine. Elsewhere on the forum some post said the finer the grind the more clumping or at least the tighter the clumps will be and the more prone to channeling.

I do think it is a grind problem.
The other matter is that if the grinding surfaces are uneven then the grind will be so this can contribute to clumping. We had a new grinder that took 12 months to wear in. Now it is perfect. I am not sure why your Rocky seems to be causing problems now.

We use either Cimbalino's or Dimittina fresh beans one grinder soft clumps the other no clumps, but no channeling.

Do you know the brew pressure of Silvia? The very early ones V1 were around 12 bar, I lowered mine to 9bar. It sounds like yours should be okay.

[WME]

Thanks a lot to everyone for replying and helping out.

Ordered a new screen and put that in the other day which eliminated the majority of channeling issues.

Thanks guys, have also tried as you suggested using more of a distribution and breaking up the clumps with a skewer which seems to have helped massively with getting shots back close to where they are.

Thanks a lot guys, not to sure why I'm getting bigger clumps now, perhaps oilier beans? Bit of a pain individually breaking up clumps but worth it to get a nice cup.

Thanks again [emoji106][emoji106]☕️