MWJB

OK so the bitterness in the 1:1.9 shot isn’t over-extraction, because if it was the 1:3 shot would not have been better.

Very useful to learn that 🙏

MWJB How are you able to stop the shots exactly on the weight to 0.1g?

I just double checked my note. The liquid should be 54.2 (instead of 54.0). I will edit the typo.

MWJB The shot you videoed, 1:3 assuming 15s pre-infusion and 30s “pull time” would be 45s total, but you have coffee running for another 25s?

Yes. All with 15s pre-infusion. I am unsure if I can answer the workflow clearly but here are what I did:

  1. Preinfusion for 15s. Pull the lever down until seeing the first drops and maintain the same pressure without further pulling down for 15s.
  2. Started pulling down with higher but steady pressure for 30suntil the end of the shot. I feel it was like 6-7 bar. I define this as “pull time” this is where the fluid comes out.

So, the total preinfusion+pull time was 15s + 30s = 45s. Fluid mainly came out during the final 30s.

MWJB Try 1:3 again a bit coarser to see if you can reduce bitterness

Thanks. Glad to have the advice and direction. Without this, I may have bend steered by the bitterness to go coarser and go back to my endless cycles.

          1. Grind 2.1.0/ 1:1.9/ 18.0g to 34.2g, pull time: 16s [3.0/10] (very bitter)

          2. Grind 2.0.2/ 1:3.0/ 18.0g to 54.2g, pull time: 30s [4.5/10] (same bitterness but less striking and with some sweetness)

          3. Grind 2.1.2/ 1:3.05/ 17.7g to 54.1g, pull time: 27s/ 4 bar by feel [4.7/10] (less striking bitterness and start to taste a little bit sourness)

            (note: this time I weighted the ground output from grounded. Notice quite a bit retention with this new beans, which are oily and sticky)

          Guess next maybe I should go a bit coarser?

          • MWJB replied to this.

            Knluk Is that 3 new brews since yesterday, or have you repeated the first two?

            You should always record the ground weight of the dose.

            If the sourness is not offensive and you can take a little more and if it reduces bitterness, then yes, go coarser.

            What would your score be for the automatic machine?

                MWJB

                I just made one shot today. The first two were just copied and pasted for easy reference.

                i would score the automatic machine as 7.

                The sourness is not unpleasant. Ok. Will go a bit coarser for experience. Can I also shorter the shot a bit? Think it is stretching the limit of the Robot’s basket, where water is filled for brewing.

                • MWJB replied to this.

                    Knluk Just list new shots please.

                    Try 50g out?.

                    If you need to extend the ratio, you understand that you will need to reduce dose size, if you can’t reliably hit more than 50g out? (change grind or dose, one at a time).

                        MWJB ok. One change at a time. Just to make sure I understand your correctly. So you mean if I want to yield 50g liquid, I should use 16.7g coffee to maintain 1:3 ratio?

                        • MWJB replied to this.

                            Knluk First off, just try coarser & 50g out.

                            Then if you can’t shake disagreeable sourness, without also increasing bitterness (by grinding finer), try reducing the dose.

                              Shot this morning. Can feel it start to be more drinkable. But also have problem:

                              • Grind 2.2.1 (coarser than last shot)/ 1:3/ 16.7g to 50.1g, pull time: 15s/ 6 bar by feel [5.0/10] (taste wise a bit more balanced and more creamy)

                              This time I coarse the grind a little bit. But because the robot means to works in higher pressure. So I tied to use more pressure this time. So the pull time reduced to 15s. Wonder I should go back to finer or reduce pressure.

                              thanks!

                                Cafelat Robot user here but I’m rather late to the thread, I’ve skimmed the other replies so apologies if I’ve missed or am repeating anything.

                                As others have mentioned, the thermal stability of the Robot is very good and the beans you’re using are dark. I know you mentioned you’re letting the water sit for 20 sec in the kettle but the temperature is unlikely to significantly decrease in that time in an insulated kettle. This will definitely be contributing to the bitter flavour - try a thermometer and aim for lower temps, you’ll be surprised at how much it improves the shot.

                                If you’re still struggling with bitter notes I’d shorten your brew ratio, decrease the pressure you apply (6 bar is fine) and finally decrease the preinfusion time. Don’t worry too much about brew times, but again with it being dark roast I’d guess shorter will be better. Finally do as you’re doing, change one variable at a time and record how different grind settings, ratios, temps all taste.

                                Also see if the cafe who brewed the espresso you liked with those beans can give any tips on how they do it.

                                As others have mentioned the Robot is a very good and capable machine (and the JX-pro a great hand grinder) but manual levers can be challenging even for experienced home brewers. It sounds like you’re on the right track so stick in there and please shout if you have any more questions or issues.

                                  MWJB noted. I was kind of worried that the pull was too easy leading to inadequate extraction. So I tried to use the bathroom scale approach and make sure I make 40lb pressure. But then I found the shot very fast (15s to produce 50g liquid) even when the ready was 30lb. Will try coarser and see how it goes and report back.

                                    FadedFrontiers

                                    Thanks for the advice. Can’t wait to see the result after lower the temp. I actually taste some burnt taste in the bitter (with my untrained tongue) so maybe temp is really the cause. Do you also recommend me to fill the PF 1cm to full?

                                    Re the pressure, I previously did underestimate how much force I should apply for 9 bar. After I put a bathroom scale underneath to check, I found I really have to muscle it down at the end. Will try 6 bar and reduce the length of shot and see how it goes. I think that will improve the brew time although it should not be the focus.

                                    I will finish this bean in two days. Next ones will be medium dark and medium roast. How would you approach the first dial in in term of ratio?

                                    thanks

                                        Knluk After I put a bathroom scale underneath to check, I found I really have to muscle it down at the end.

                                        Bear in mind that a lever (spring or manual) usually has a declining pressure profile, and this is generally seen as a positive characteristic. You may want to try NOT to maintain a steady 9 bar pressure through the very last seconds of the shot, and see if things improve. However, as others have said, change one thing at a time.

                                            Knluk no problem, I imagine you would have found the best grind setting before but the high temperature made it taste too bitter. It’s easily done.

                                            Because of its design that minimises the contact (and heat transfer) from basket to portafilter, the Robot doesn’t drop temperature so quickly like the Flair. Off the boil water into the basket usually results in a starting brew temp of round 90c-ish so for your beans I would aim to lower the basket temp down gradually towards a minimum floor of 85c to see how that tastes.

                                            Yes I usually find that filling the basket with water to around 1cm from top works fine. You can leave slightly less space at the top you just run the risk of spilling hot water when you lock it in. I can’t imagine this will affect taste dramatically unless you do what Hoffman did in his review and underfill it too far as that could make it harder to generate pressure.

                                            You’ll soon get a feel for the pressure and it comes more naturally now you have an idea of the correct range. As CoyoteOldMan mentioned usually you build up to pressure quite quickly then you slowly decline towards the end of the shot, so don’t worry about sustaining the max pressure for any period of time. I usually go off the feel and flow from the basket and adjust accordingly but it took time and plenty of bad shots!

                                            Once you dial in a few different roasts you’ll also end up defaulting to different starting parameters depending on your preferences, but I’d say aim for a 1:2 ratio for dark roasts and nearer 1:2.25 for medium ones (lowering the dose and raising the ratio and water temp for even lighter beans since they’re harder to extract). As mentioned the important thing is to keep your starting temperature, ratio and preinfusion consistent as you dial in the grind. Then tweak them one at a time to perfect the taste in cup.

                                            Lastly don’t beat yourself up for a bad cup, just write down notes that you might find useful for next time so you can improve with the next attempt. Your shots look a lot better than what my early shots were like. Good luck!

                                                The best thing I got here besides the technical advice was the encouragement. Here you go for another experiment incorporating the valuable comments:

                                                Same: beans/ tampering technique/ dosage (17.7g)

                                                Change: coarser grind/ temp 92.1 degree Celsius (measured at kettle)/ zero preinfusion/ 1:2 ratio/ brew time

                                                Learning: I cleaned and calibrated the JX Pro and I thought I set the same burrs gap. (Maybe I messed it up). However, it seems to me that the resultant ground is way too coarse (unless it is channelling, what do you think after viewing the clip below?)

                                                So, I finished the pull at 9s with 4bar pressure at peak. The liquid is watery and bitter. Think I should make the grind setting much finer.

                                                Another thing was I greatly underestimated how much force I should use for the indicative pressure eg 4bar/ 6bar. That’s why the shot became much faster now after I paid attention to it

                                                Probably worthless to watch but here is the clip:

                                                  Knluk the resultant ground is way too coarse (unless it is channelling

                                                  One thing does not rule the other out; I think you have both: see the spritzing at 0:03 0 0:04 as well as the general speed of the shot and the not great taste result. Definitely grind finer!

                                                    Knluk yes I would definitely go finer but I’d probably go with 95c at kettle as a rough starting temp for those beans (as it will drop immediately when it goes in the basket). I know it seems like a small amount but in my experience it can have a noticeable effect on taste.

                                                    Instead of working your way backwards grinding finer and finer again, it could be worthwhile finding the grind setting where you had the best shot and try that just with 95c kettle temp water. Then adjust accordingly, if it’s still too bitter, takes long, or requires a lot of pressure to pull the shot then go coarser with the grind, and vice versa.

                                                        Knluk Grind 2.2.1 (coarser than last shot)/ 1:3/ 16.7g to 50.1g, pull time: 15s/ 6 bar by feel [5.0/10] (taste wise a bit more balanced and more creamy)

                                                        By far, this was your best shot, unless I missed something, thanks to @MWJB. As FadedFrontiers advised you, please start at those parameters, take your temp at about 95c, and post the details of your shot and the score.

                                                        Furthermore, please don’t forget this :

                                                        MWJB Don’t worry about the pressure.

                                                        Try coarser until you get unpleasant sourness/thin shots.

                                                        It’s easy to get lost. You are doing great and being helped by those who have similar set ups, knows what it takes to get a good cup and also by our own go to person for coffee/brews/beans @MWJB. He is our Coffee / Brew God !

                                                        😊

                                                              Thanks all for the helpful inputs. I have to sit down to think about my next trial. I still have the same beans for ⅔ shot to try. I have a fantasy that the Blackcat and Northstar beans will make a night and day difference

                                                              No matter what, through all the advices here, I start to get a little more sense on how I assess the espresso based on taste and get some improvement on the next shot. Although sometime it may be confusing but I think experience counts. Will report back my next shot if you don’t mind.

                                                              Knluk Please keep everything the same as per your last best shot, where you had scored 5/10. Change only the temperature to the required level.