Hi,

Here is my brew recipe using the Cafelat Robot and Kinu grinder.

-water: 99.5 degrees
-Dose: 16 grams in hoping for 32 grams out ( I also tried 17/34)
-timing: 5 second pre-infusion at 1 or 2 bars, then another 15 second pull at 6 bars, then 5 seconds of slowly winding to zero bar.
-Beans: dark roast (psychedelic sunrise by Disco Coffee) about 10 days from roast date

Using my Kinu grinder I tried various grind settings (I've tried several shots between 1.1-1.3 and 1.1.2 seems to get me the closest end weight unless I am way off due to channeling I am not seeing). Generally the shots are still coming out about 5-10 grams too heavy and taste terrible. I wanna say it is too bitter but I am too new to trust the difference between sour and bitter so I could be wrong. I try going finer but I get channeling. I tried going coarser but the water just runs right through the puck in no time.

pre-infusion looks good, I am not seeing channeling. the puck looks good when I dump it.

I am VERY new to all of this and I feel like hitting my head against a wall. Any advice would be appreciated.

cheers,

A couple of caveats, I don't do a lot of dark roast stuff ( I got some over the holidays and passed of to DW) I 've never seen a Kinu live and in person. Typically I dose 17.5 and about 35 out--pretty sure this is not your problem as you have tried 17/34. So. . . .
1. Not sure you need a pre-infusion with dark roast, again probably not your problem. 2. You do need to figure out the difference between bitter and sour--it is the difference between under extraction and over extraction. Sour is citrus, bitter is cruciferous veggies or unsweetened chocolate, for example. 3. My pulls are generally longer--25-low 30s and at higher pressure. While I don't necessarily do much of a pre-infusion with darker stuff I do a gentle ramp up and hold the shot at around 8bar for all but the last 5 ish grams--which I decline to about 4 bar before ending the shot--all the ishes and ranges are because I am lazy and the Robot is very forgiving. 4. How the puck looks is irrelevant with a Robot. How the shot looks while being pulled is relevant. If I did what you did with the beans I generally use--not as dark apparently-- my shot would be under extracted--sour.

I would be inclined to updose your darker roast and grind finer, and/or maybe reduce your ratio to 1:1.5-1.75.

Very helpful thank you! I am going to experiment under the assumption that my shots were underextracted. I am looking forward to trying again tomorrow.

No pre-infusion for dark roast...did not know that!

How long do you suggest I take to ramp up to 8 bar?

When I say 5-10 grams too heavy I mean I weigh 16 grams of coffee in the hopes the espresso weighs 32 grams but it ends up weighing 37 grams up to 42 grams ( so 5 or 10 grams too heavy). I am sticking to a 1:2 ratio.

I see you are deviating from what I understand to be the traditional recipe.... 1:2 ratio (I know this changes a bit based on dosage) and 20-30 second shot time. I am too new at this to understand why one would steer outside of this other than personal taste/preference and experimentation, but since I am new I am trying to start with a traditional cup. Perhaps with some beans this is just impossible and deviations are required?

You asked if I've tried this roast before. This is my first day making espresso. I can't believe how hard this is. I mean I knew it would be hard but I feel like an idiot wasting 8 cups today.

It takes a little while, so don't get discouraged.

Try to go longer than you are going for the actual pull. Pre infuse as you have been and then go for about 25 seconds for the actual pull and don't take 5 seconds to go to zero. It could be good to reduce pressure on the handles at the end if it starts to run faster, but I don't think it should be a 5 second ramp down to zero. See how this tastes and go from there.

What coffee are you using? Some are more sour and some are more bitter, some are more fruity and some more burnt, so choose wisely. There are coffees that I buy today that I just don't like, and in the beginning I probably would have blamed the tastes I was not enjoying on myself and not the roast.

My niche zero came in yesterday (heard kinu's all have different zeroes/starting points so perhaps this will be easier to determine if grind size is the issue).

New Recipe:
-Niche grind size 15
-water: 99.5 degrees
-Dose: 18 grams in hoping for 36 grams out
-timing: 30 seconds at 9 bar (no-pre infusion)
-Beans: dark roast (psychedelic sunrise by Disco Coffee) about 10 days from roast date

The shot was spot on in terms of the recipe above except the end cup was .7 grams over target weight and it took closer to 26 seconds to reach. I wish I knew sour from bitter but it tastes pretty bad. Here is the kicker. I had this bean as an espresso at a local shop and it was not good. I only chose it because it tastes great as a pressed coffee, and I was hoping that this shop did not know how to make a good espresso. When I had it as an espresso at my local shop it tasted pretty much like it tasted just now.

Can you tell from the pic if this is over or under extracted? (Note the glass is large)

At this point I am thinking of putting some research time into finding the right bean and hoping for better results.

Side note, I live in a DC suburb and when I went to DC to try a bunch of espresso (just walked around and stopped at random places) I did not like any of the shots I had. I would not characterize any of them as having any subtle notes of "sweetness." I have had good espresso from those fully automated machines and also those machines that have everything in one (like a dual broiler machine with a built in grinder) but I do not recall the beans used.