vit wrote:Machines in lower price range are often advertised as producing 15 or even 20 bar. It's the pressure that vibe pump is producing at zero flow. In reality, due to presence of "coffee valve" at the bottom of the boiler and lower quality pumps being used, real pressure on the puck on most of those machines during the shot is something like 6-8 bar, depending on the flow

As about the grinder, most of them don't produce best result at the point when the burrs start (or almost) touching, because it's way off their optimum zone and consistency is suffering (there will be lots of fines but still some boulders among them), so have that in mind. It's better to go slightly coarser than that and updose

If the flow was much higher than previous shot on DeLonhgi machine so that you couldn't reach at least 5-6 bar (I suppose it was the same or previous day and not something like a month ago, so that beans degassed in the meantime), main problem should be something else, although surely alignment of the grinder is worth checking and Robot most likely needs somewhat finer grind than DeLonghi

Have in mind than in 58mm basket puck preparation is much more challenging than in smaller baskets, so when dosing, try to achieve distribution as even as possible before tamping to avoid channeling. Robot has deep basket so it's even more challenging than ordinary espresso basket. Uneven distribution can't be entirely "corrected" with tamping. You can use a needle, paperclip or some other similar improvised tool

Another problem in "pourover espresso machines" like Robot or Flair is that way of pouring might also cause channeling, especially if gooseneck kettle is used, so that the water is hitting the small spot on the shower screen. It should be visible by observing the condition of the puck after extraction - it might have uneven surface or some parts might be considerably softer than other. Try putting a piece of filter paper below the shower screen, with diameter matching the diameter of the basket and see if that helps. In both my "pourover" machines (Flair and Kompresso) it improves the result although both of them have the shower screen

Also, for the beginning, try with shorter preinfusion or just with about linear pressure rise within 5-10 s to see if that helps and leave determining the optimum preinfusion length / profile for your taste and beans for later time

imp96 wrote:Posting a video would probably be the best way for other to notice the issue.

Corgo wrote:Any chance the pressure gauge is off or defective? I get 2 bars by barely pushing the levers and use 2 bars for preinfusion. Just pushing it so it pulls the shot is closer to 4 bars and I have to apply a little bit of force to hit 6 bars. If I am pushing very hard on it, I would be the the 10 bar mark. Wonder if OP tries to dial in by ignoring the pressure gauge might actually work.

yakster wrote:Have you tried freshly roasted coffee? Also try 18, 20, even 22 grams of coffee in the basket to see if you can feel some back pressure from the coffee when pulling the shot. Try using water right off the boil.