Having trouble with Cafelat Robot

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Starguru
Posts: 78
Joined: 9 months ago

#1: Post by Starguru »

I got my robot roughly a week ago and am struggling to pull decent shots. I've tried 16-19g. With WDT. I usually start with pre-infusion, then go to 6-8bar of pressure.

No matter what I do somehow get sour yet also bitter shots. I never get anything close to sweet.

Also I can't seem to get more than 40ish grams out. I fill the portafilter to about 1cm from the lip, and the arms all the way up. I notice that the arms go about 1/4 to 1/3 of the way down during the pre infusion.

I am using a Zerno Z1 at about 165um setting.

Any tips?

Edit with more details:
SSPV2 burrs.
I have both medium and a roast on the lighter side.

Using my phone I watch the shot; it starts out looking real nice, with even flow from the bottom, but mid to end I get a bit of a vortex type flow.

jgood
Posts: 903
Joined: 6 years ago

#2: Post by jgood »

I usually use a higher pressure -- ie 10 -12 -- tapering down at the end of the shot. Preinfusion of 16 -20 sec. (20 gr dose). I go for a 30 gr output, so I can't help you there. What roast level are your beans? How long are your pulls? Have you tried higher pressure -- which may mean grinding finer?

Jonk
Posts: 2195
Joined: 4 years ago

#3: Post by Jonk »

We need more information. What burrs are in the Zerno?
Is this your first espresso maker?

You should be able to get a lot more output. Fill the basket more so there's minimal air left when you lock it in, about 3mm from the lip.

Starguru (original poster)
Posts: 78
Joined: 9 months ago

#4: Post by Starguru (original poster) replying to Jonk »

Updated with answers. My first espresso maker was a Bambino. The robot is my second.

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Jeff
Team HB
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#5: Post by Jeff »

If the Cast v2 burrs, they may need some seasoning before they settle down.

I get good shots without going to high pressures. I think Paul Pratt thought 6-7 bars was plenty. I agree. You might try lightening up during soak, just light pressure on the arms is enough until it seems the puck is well saturated.

Jonk
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Joined: 4 years ago

#6: Post by Jonk »

SSP V2 what? They'll both pronounce acidity if there's any left in the beans. If it's MP, forget medium roasts. Pre-heat the Robot's piston with a big cup of water and do an 'overflow pour' i.e. let hot water run over the side of the basket into the sink for a while before locking it in (careful not to burn your hand :!: it needs to be tilted away from you)

You might also want to aim for longer shots, 1:3+

With the cast burrs you can use any roast level you like. Darker roasts will mean less acidity and more traditional shots.

I don't have a Zerno, but at least with my grinders I need to grind finer with both of those burrs (V1 though). I wouldn't force the shot to run slow with the cast burrs though, best to aim for a relatively fast shot IME.

Starguru (original poster)
Posts: 78
Joined: 9 months ago

#7: Post by Starguru (original poster) »

Jeff wrote:If the Cast v2 burrs, they may need some seasoning before they settle down.

I get good shots without going to high pressures. I think Paul Pratt thought 6-7 bars was plenty. I agree. You might try lightening up during soak, just light pressure on the arms is enough until it seems the puck is well saturated.
Yes the Castv2 burrs; wasn't aware there was any other kind. I'll use less pressure for the preinfusuon and see how that works.

I ran half a large ziplock of old beans thru when I got the grinder, but that's probably not enough for a proper seasoning.

Starguru (original poster)
Posts: 78
Joined: 9 months ago

#8: Post by Starguru (original poster) »

Jonk wrote:SSP V2 what? They'll both pronounce acidity if there's any left in the beans. If it's MP, forget medium roasts. Pre-heat the Robot's piston with a big cup of water and do an 'overflow pour' i.e. let hot water run over the side of the basket into the sink for a while before locking it in (careful not to burn your hand :!: it needs to be tilted away from you)

You might also want to aim for longer shots, 1:3+

With the cast burrs you can use any roast level you like. Darker roasts will mean less acidity and more traditional shots.

I don't have a Zerno, but at least with my grinders I need to grind finer with both of those burrs (V1 though). I wouldn't force the shot to run slow with the cast burrs though, best to aim for a relatively fast shot IME.
Yes the cast v2, sorry I wasn't aware there is more than one type.

Starguru (original poster)
Posts: 78
Joined: 9 months ago

#9: Post by Starguru (original poster) »

Ok, I tried longer pre infusion and got somewhat better results today. The sour is going away but is still present, and the overall coffee is more balanced, but still bitter. The espresso produced does fine in an Americano but I wouldn't want to drink it straight up. I've also started grinding finer to facilitate pressure. Im at 150um on the Zerno, with 18g in. I will say it gets pretty difficult to get above 8 bar, even using my body weight. And the damn pressure gauge is next to useless. I perform the extraction with the robot faced away from me, so as Im above it I can look over and kind of see the pressure gauge, but everything is reversed.

I still notice that the shot starts looking pretty good initially, but towards the end I get the "tornado" effect. I guess this means the puck degrades and I should lower pressure? Are there any other tips?

thirdcrackfourthwave
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Joined: 5 years ago

#10: Post by thirdcrackfourthwave »

The 40 grams was/is a huge red flag for me. I did one pull today, so small sample size, but I got around 68-69 grams total. Ftr after a fair bit of trial I've just settled on 18 gram doses for just about every shot. I'm curious why you are only getting 40 grams max out.

And yes, ramp up slowly after pre-infusion and ramp down slowly at the end of shot