Knluk How many coffees are you going to make per day?

A 250g bag holds 14× 18g doses max, so 2 weeks even if you make 1 shot per day.

If resting 2 weeks, brewing in the next 2 weeks, it will be fine to leave the beans in the resealable bag.

The consensus for 70yrs has been that freezing preserves coffee. But if freezing, freeze in small, rested, batches/doses that you will use straight away (hence vacuum sealing in portions).

      I had a Robot and all the best advice on using it comes from the inventor on the Cafelat YouTube channel, you can see how he preps and pulls shots. Hoffman does mention his technique in the review but I’d stick with the guy who invented it to start with before experimenting.

      I wouldn’t get too obsessed with bean storage and hitting some mythical sweet spot window when they aren’t too fresh or too old, to start it’s about grind size and technique on this machine. There is no need to pre-heat either according to Cafelat, people may disagree with this in general but I’d listen to people who have the machine and use it to pull shots, rather than general coffee theory.

      After you’ve got that down then you can start obsessing over the smaller details.

        MWJB I drinks 2-3 shots a day, currently using 18g per shot. Good to know I can keep it in the bag for short term. I prefer not to go too complicated for storage and focus on coffee making skill first. Thanks!

          gotters is this the clip you referred to?

          I watched that before and rewatched it just now. What I did differently was:

          • I feel 5mm to full instead of 1cm
          • I used 18g instead the 14g he mentioned.
          • I am not sure how much liquid he extracted but that look like he is using a much lower ratio than the 1:2 i normally used. I was told to try longer shot. I tried 1.25 yesterday but it was bitter. I think that’s sign I either over extracted the coffee and/ or the shot it too long so I captured too much of the later liquid which is bitter(?)

          Would love to hear your recipe in term of ratio and gram of coffee.

          great advice on the storage. I feel very relieved.

            I took the advice from above. Went back a cafe that served me the espresso I really like and bought the exact beans he used. I enquired about the lack of roast day and he said once the beans were roasted, they were rest and packed with gas inside an expensive valve bag. So as long as it is not open, it can be kept for months without problem. I know it is contradict to the opinions of almost all home espresso enthusiasts here. But the North Star and black cat beans I have are all too fresh, why not give it a try. At the end of day, the barista used this to produce something I like.


            From appearance, the beans are dark and oily. Smell pretty nice (this is useless comment though as I like the smell of any coffee). I applied the knowledge I recently learnt and here was my plan for the first trial dial in:

            • it is pretty dark. And I tried 1:2.5 in my old bean yesterday and it was overly bitter. So to avoid I capture too much of the bitter shot in the last part, I reduced ratio to 1:1.9.
            • It is pretty dark. So I worried about over extraction, so I sit the boiling water in the kettle for 20s before pouring. And I changed my grinder setting by 2 dot coarse

            Here are what the resultant drink:

            • pretty thick body
            • Very dark in colour
            • Drinkable but nothing close to good. Less bitter than my last shot with 1:2.5 ratio. But the bitterness is still pretty striking.
            • I made a latte with it. The bitterness and burnt taste still quite profound.

            Grateful if I can have some advice on the next trial dial in? I am thinking keep everything the same but go coarser? Maybe further increase the ratio to 1:1.8?

              Knluk It is very, very unikely that you are over-extracting, so don’t worry about it. You’re not measuring it anyway, so tell us how much you like/dislike, rather than second guessing unusual faults that you can’t diagnose.

              It is much more likely that you are under-extracting.

              Bitter happens for many reasons, not just one. Over-extraction is an intensely drying, smoke like bitterness, you’ll know when you get it. The result will not be drinkable.

              You’re going round in circles if you go shorter, you’ll be grinding finer, making more bittering silt & the coffee will be so intense you won’t be making sense of it. Eventually you go too fine & extraction drops again.

              Coffee is bitter, coffee is sour, it is often bitter & sour at the same time. It was roasted & is often charred/burnt…none of these things is helping us troubleshoot. Give us a numerical score, grind setting & ratio so we can see how they relate. Every bag of coffee tastes different but the dial in process is the same and the same things apply to all of them.

              I’d go 1:3 and coarser until the coffee starts becoming too weak and tart/sharp, then tighten up the grind to where it tasted best. If you need more concentration, then look to shorten the ratio.

                  MWJB Yes. You could see my feeling. I really feel like circle. I was at 2.1.0 (on the coarse side) setting before. And tried to go fine to 1.4.2 where I choked the Robot. The I slowly step by step open the grinder to 2.1.0.

                  Do you mean I should report back something like this:

                  • grind 2.1.0, 1:1.9, score 3/10
                  • Grind 2.0.0, 1:3, score 5/10 (this row is make up number)

                  Really appreciate your advice. Cos I really directionless on which side of the spectrum in grinding or ratio I should heading to.

                  • MWJB replied to this.

                      Knluk Yes, you are preinfusing for 15s anyway, so also include the total shot time. Probably best to put the final shot weight too as you can just read that off the scales & 1:1.9 an 1:2.0 are essentially the same thing (so close that when you consider natural variation and noise, you can’t be sure where the difference is coming from).

                        I apologise if my tediousness upset anyone 🙏

                        But I am really need some suggestion on simply whether I should go finer/ coarser/ longer/ shorter ratio as maybe I am less talented in understanding coffee making after quite a bit reading. Hope I can grab the basic skill quick for dial in.

                        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)

                        Thoughts: this hobby is really difficult I expected 1:3 will extract lots of the bitterness at the end of the shot so it will be even worse I tried with doubt but suprisingly it shows some improvement. Btw, I extracted the last drop while filling the robot 1cm to full. I may need to fill up a bit higher next.

                        Video if helpful:

                        Thanks as always!!!

                        • MWJB replied to this.

                          Knluk I can’t imagine anyone getting upset, people can choose to engage or not :-)

                          Knluk Grind 2.1.0/ 1:1.9/ 18.0g to 34.2g, pull time: 16s [3.0/10] (very bitter)
                          Grind 2.0.2/ 1:3.0/ 18.0g to 54.0g, pull time: 30s [4.5/10] (same bitterness but less striking and with some sweetness)

                          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.

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

                          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?

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

                                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.