bringyoutomyhell wrote:As you discovered you needed to grind coarser. There's a "peak" in extraction as you go finer. It's called volcano effect, the extraction is higher as you go finer until a point where it decreases again because the particles are too packed and you get channeling, creating both bitterness from the overextracted parts of the puck and sourness from the dry-ish underextracted parts with less water flow. Also fresh coffee has a lot of CO2 the first 10 days from roast, and this gas limits water contacts with the particles, again lowering extraction. The Robot has a temperature stability problem, which is a problem only for light roasts (it's better to also preheat the piston in that case), but with darker roasts you should absolutely have no problems once you nail the grind setting and using rested coffee (also the grind setting will need to change day by day as the coffee ages, that's just life )

THANK YOU! that's exactly what I was trying to describe. it tasted overly bitter and nasty, but had the solventy tastes of under extraction too, but neither felt 100% correct. That explains it too. over and under extraction in the same cup.

I dialed in a bit better today by realizing I was tamping WAY too hard as well judging by videos. I used a light 2 thumb tamp today and it was obvious my grind was too course (it was probably just right yesterday I just tamped it into oblivion)... dialed in 2 notches finer on my grinder, light 2 thumb tamp and I pulled a rather pleasant shot. like I was actually pleased with how it turned out. I think I'm finally on the right track to pulling decent shots now that I'm figuring out the feel of how much 6-7 bars of pressure is and I don't have to stare at the gauge in order to make sure I'm on the right track.

You're on the right track! Yes, tamping as hard as you can doesn't matter with pump machines, but with levers and manual levers in particular a "softer" tamp make for a more even puck preinfusion. Aim for 6-7 bars (you can start decreasing the pressure after half shot so you can slowly ramp down to 3-4 bars at the end) and you're good to go. Basically the only thing you'll need to nail is the grind

thanks, finally feeling comfortable today and can focus on grind level. I used the paper filters and that seemed to make it much more even distribution and kind of acted like training wheels in a sense. my second shot I somehow got the bed unlevel and the puck came out with an angle on top with the shot being kind of sourish (definitely channeling)... definitely going to be more careful with putting the tamper in straight. Ordered some more papers to have on hand just in case, and got the self leveling tamper too, as it's kind of awkward for a newbie with the new handle.

dumb question. How critical is a 100% perfect tamping edge? I'm probably overthinking this because I just spent money on something, but the tamper slipped out of my hand and landed on my granite counter top creating a minor "scar" on the bottom edge (picture shows it). it's not massive, it doesn't appear to created any sluff. it just hit at the right speed and right angle that it sort of created a light indented "scar". You can't feel it unless you run the edge of your nail across it and then you can very lightly feel it catch on the part that divoted in a fraction of a fraction of a mm.

am I just over thinking this (it seems to tamp perfectly fine, doesn't leave a mark when you twist it on the grounds) and letting my OCD take over, or is it something to worry about? (I know I'm probably over thinking it, but being that it's only a week old my brain is trying to tell me "It's going to eff up your espresso!!")

Try it out and report back.
You should also buy another and do head to head tests with graphs and pie charts.

: )

It seems to me that if you spin the tamper after tamping, aka "polish" the puck, you'll notice if that ding in the tamper disturbs your grounds. If your grounds are smooth, there won't be a problem.

davidhunternyc wrote:It seems to me that if you spin the tamper after tamping, aka "polish" the puck, you'll notice if that ding in the tamper disturbs your grounds. If your grounds are smooth, there won't be a problems.

that's kinda what I was hoping and thinking. The scar is just a very slight "inward" scar not one that creates sluff outwards and when testing it doesn't create a mark in the grinds at all. I was pretty sure I was in the clear but since it was only 3 days old when that happened my OCD inner voice started getting the better of me (especially since this is my first espresso machine). For the last 5 days I haven't noticed any marks in the espresso, but I used this opportunity to grab the self leveling tamper when I realized it would cost $50 to send a replacement from Cafelat directly for the OEM tamper ($10 item $40 shipping), but I just wanted to make sure it wouldn't be a problem and keep it as a back up, or if it was just throw it away

as I said, it seems to be tamping fine with no marks, but being that I have had no previouso knowledge of tamper and tamper maint I figured I'd better humble myself and ask instead of just hoping lol

on a side note, I used a medium/light Sidama roast tonight for craps and giggles and it was mind blowingly different than the dark roast. I'm using the X-pro which uses the K/Q2 heptagonal Commandante style burrs which accentuates clarity and acdity, but WOW, this was an incredibly different shot. The sidama has always been heavy on that tart strawberry flavor but in espresso form it was mind blowingly upfront. I felt like I got punched in the teeth with a HEAVILY tart strawberry (I'd almost say sour, but it wasn't that nasty under extraction sour. it really felt like a super tart strawberry more than unpleasant). Not something I'd drink straight but mixing with steamed milk basically turned it super sweet and strawberry fruity. Probably teh most unique shot I'd every pulled. (I accidentally mis measured and dosed my normal 19 gram does for filter coffee instead of the 16 gram dose for espresso, and turns out by googling I find up dosing for light roasts is kind of wanted...so pure luck it turned out as it did)

can I ask a shot flavor question here. I've gotten to a weird position with this bag of beans. I'm hitting near excellence but not quite. It's a frustrating thing as I don't know what vairable to change next with the robot to get a better shot.

here's my scenario

a nice dark roast, about 15 days past roast date right now. I've been playing with the grind and the shots all week and I've gotten some "meh" shots and some shots that taste excellent in a cappuccino. However, they're almost all tasted SLIGHTLY sour. Not horrible, just enough to where I notice it if I taste the pure espresso. I've changed variables such as dropping dose and grinding finer (from 18 grams to 16 grams, which made a big difference) and I've gotten to the point where I've ground finer and finer until I hit a weird spot. The under extraction sourness is ALMOST gone (but still there just a little bit) and the roast is finely dark and mildly bitter. however it has a finish that feels dry and a bit TOO bitter if you know what I mean. I'd normally assume to back off the grind to get rid of that hollow/bitter finish but if I go one click back the sourness increases, so I'm kind of at an impasse in terms of that variable.

below are the specs at which I'm pulling

16 gram of dark roast from Savaya (their singer songwriter blend)
34-36 grams out
10 second pre-infusion at this grind level
6-7 bars of pressure
X-pro grinder (12.5 micron adjustments)

if I go finer the finish smooths out but the sourness increases as well. Also at 39 clicks here (where I'm at here) if I go any finer I get VERY obvious side wall separation on the puck and the shot starts to get very uneven. one sip is smooth, another sip is sour. Which means I'm probably going sour on that shot and above due to channeling. (duh)

my question is, what variable should I adjust next? should I updose a gram? at the 39 click mark on the grinder it's already a tough pull (which is the shot that gives me a hollow/bitter finish with MOST of the sourness gone) so I don't want to add too much pressuure (though backing off one click AND updosing might change that... not sure)...add a longer pre-infusion???

increase or decrease presssure???

now don't get me wrong. if I put these into a cap or latte they taste pretty good (better than your average chain store by far) but tasting them straight up I can definitely tell they're "off" and I can't seem to get rid of this sourness no matter what direction I go (hell, for all I know it's the beans)

Jonk wrote:Don't worry about the dent.

For those very bright coffees, it's a good idea to pre-heat the piston in my opinion. Pretty easy thing to do if you can find a cup that fits around it, I let mine soak while prepping the puck.

thanks for the comment about the scarring. pissed me off as it was brand new, but if it's not a problem no big whoop.

and I didn't think about heating the piston... the bowl was something to try I didn't think of the piston