So everyone having issues with side channeling, weak body extractions without heavy pre-infusion here is what i have discovered that completely changed my extractions with the robot.Disclaimer:
This might all be total crap and just accidentally fit my style, setup whatever. Check my first post about the Robot i got two and love them to death.So story:
Like many others i noticed that it was kind of hard to get those syrupy extractions from the Robot. Recently i also had a few issues while using heavy dark italian roasts that do not do well with low pressure, long pre infusion at all. Ramping up faster without a lot of pre-infusion always left the stream swirling, weak extraction, typical channeling issues. I started putting the Robot near the edge of the kitchen counter to watch the extractions from below and noticed that flow would always start from the outside - doughnut extractions - no matter what tamping style, tamping pressure etc, which grinder (helor flux, niche zero, kinu m47, kinu m68) - which beans etc pp.
Doing low pressure long pre-infusion like everyone advises with the robot here fixed that to some degree although not completely (syrup body, dark roasts become very unpleasant). Going faster on the pre-infusion and ramp up + max pressure (usually above 6bar this would start to be very noticable) you would notice that it would just side channel no matter what you do.Solution:
Today it clicked. The edge of the shower screens that you pop in before filling with water are edged down and cut into the puck where?... at the wall of the basket...
First try: I cut a piece of chemex filter the size of the shower screen and just that as a shower screen to be able to fill in water without disrupting the puck too much. Boom... first extraction instantly WORLDS apart in body, side channeling etc pp from using the supplied shower screens. I repeated that... every single extraction as perfect as it could be no matter the pre-infusion, ramp up, final pressure.
Cutting those papers is not very user friendly though and you get a bit of blooming at the beginning, no temperature drop on the boiling water etc so i thought well lets just flip the shower screen. This is of course not ideal as the little knob will be pressed into the middle of the puck but since there are no holes around it etc pp i thought i would give it a try.
Sure enough that worked perfectly too on the first couple tries.
Sooo... give it a try if you miss that syrup body and or got side channeling issues.
@Paul_Pratt Any chance to get shower screens that are just flat instead of bent down? I could probably just go the a machine shop around the corner and let them cut a stainless disk with holes or rasp off the bent down edge but well it might be interesting for you to look into this in general for future versions in case others find the same issue with this and it is not just my imagination (which is perfectly possible