# Extraction issues - Rocket Cellini V1



## cedriklizotte

Hi! Long time lurker, first time poster. I own a Rocket Cellini V1 and I've always had serious extraction issues with it. It under-extracts. It takes about 6 seconds to get 50 to 60 ml. According to the Rocket documentation, I should be waiting 25 seconds for my 50 ml of coffee. Of course all of my coffees are super sour.

I tried everything:

- I own a grinder. It's set on the finest grind. In order to troubleshoot, I bought pre-ground Lavazza "crema e gusto", but the issue remains.

- I tried to tamp as hard as I could. I add a lot of coffee, tamp extra-hard; sometimes I put so much coffee that the handle wont go in the machine, so I have to remove a bit of coffee and tamp again and try again. I do get an acceptable coffee once every 3-4 times using this method, but I'm nowhere near the 25 seconds of extraction time.

- I tried lowering the pressure of my machine. On the gauge, there's a little green line to show the suggested pressure, and that green line is between 1 and 1.4 bar. I lowered it all the way to 0.75, but it's changed nothing.

- I'm using the single handle and the single serving cup inside of it. Using the double handle with the single serving cup (obviously) has no effect on the result.

Can anybody suggest anything that might be the issue, here? Did I forget anything? Could the machine/handle be to blame?

Thank you!


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## Glenn

A few questions to help troubleshoot.

What type of grinder?

Do you have scales?

How much coffee are you putting into the single or double basket?

Do you have a tamper?

Where are you based?

In my experience it's extremely unlikely the equipment is to blame.


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## DavecUK

How about simply grinding coarser?


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## Mrboots2u

DavecUK said:


> How about simply grinding coarser?


60 ml in six second and you want him to grind coarser


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## cedriklizotte

@Glenn :

- What type of grinder?: It's an Isomac Granmacinino. Conical burrs.

Do you have scales?: Not as far as I know, but I don't know how to check that.

How much coffee are you putting into the single or double basket?: You mean by weight? No clue. As much as I can. How much should I be putting?

Do you have a tamper?: It's a plastic tamper, the one that came with the machine.

Where are you based?: Canada. It's water from an underwater well. It's quite hard. But we've also tried with bottled water, which has no effect.

@DavecUK: Well I know I'm a newbie, so correct me if I'm wrong, but the coarser the grind, the quicker the extraction, so...


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## Glenn

First things to get;

Scales

Proper Tamper

Once you have these then you will be able to start experimenting with the weights

Stop using the single basket immediately - they are notoriously difficult to get right (unless you have a lever - then its a whole different ballgame)

Use the double only, and start at 16g of coffee

Tamp firmly and see what happens

Then try .2g increments either way and see if you get a decent shot

Without both of these items you will struggle.

Report back when you have these.

By proper tamper I mean a well fitting metal based tamper

It will be heavier and will likely fit the basket so much better (with no gaps around the sides)


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## cedriklizotte

@Glenn,

Oh! Scales! I thought you meant scaling. Yes, I do have a scale. And the tamper has absolutely no gaps around the sides.

I've just tried exactly 16g in the double basket. Same: superfast, no extraction, less than 4 seconds for my 50ml, no wait time between turning the machine on and seeing the coffee run through, ultra-sour coffee.

Any clues?

(Thanks for your help!)


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## Mrboots2u

Grind finer , get a better tamper , that plastic one will be rubbish

How old is the coffee ( from roast date )


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## cedriklizotte

I'm not sure about the roast date, but I bought it yesterday in a speciality shop, the best in town... they sell to most of the really good coffeeshops in the city. And I've tried with 3-4 different coffees, too...

It doesn't grind finer, and I've tried with pre-ground Lavazza, with the same effect.

Ok, I'll check for a better tamper.

Is there anything else that could be the cause of my issue?

Thanks


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## johnealey

IF, the pre ground lavazza is coming out at the same rate as your finest grind from your own grinder then it could be that you have an issue with the grinder just not going fine enough, if that makes sense. This is based on use of the same tamper and roughly the same amounts in the basket to date, so could be way off the mark.

One of the only ways you are going to be able to test this though is to get some known fine ground espresso, maybe from the same place you got the beans referred to above at the same grind as used on their machines.

If this pours at a more respectable rate then the grinder is the issue (although would still ditch the plastic tamper as you may well be introducing some form of channelling around the edge of the puck). If it doesn't then move on to the how the grinds are put into the basket, each time ruling out a link in the chain.

Would also get in to the habit of not only weighing the grinds into the portafilter but also the weight of liquid coming out rather that volume as differing coffees give different volumes, crema etc

Hope of some help and that you sort this soon

John


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## DavecUK

cedriklizotte said:


> @DavecUK: Well I know I'm a newbie, so correct me if I'm wrong, but the coarser the grind, the quicker the extraction, so...


rather than say are you turning the grinder knob the wrong way, which you could have been doing?..I was trying to be kind and attempting you to turn it the right way without saying so. Anyaway, the grinders crap and some of them are not capable of grinding fine enough for espresso whatever you do. I'm not just pulling these comments out of my arse...I did test a few and some had the problem that they were incapable of grinding for espresso and those that could, were a very poor quality grind..

I strongly suspect that if you're not turning the grinder dial the wrong way...let's presume you're not, changing the grinder should solve the problem.


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## MediumRoastSteam

Also, the OP says it is a conical grinder, which are known to retain a lot in the chamber / burrs. @cedriklizotte, do you purge the grinder before you pull the first shot?

My advice would be to grind finer as much as you grinder allows. Purge some before you pull a shot. You should be able to choke your machine.

PS: Rocket Cellini v1. You have adjusted the Service Boiler pressure (to 0.75 bar). That has no influence what so ever on the brew pressure. Brew pressure should be around 9bar while pulling the shot. Leave the Service boiler pressure in the green zone, as that has an effect on your water temperature and steam pressure.


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## cedriklizotte

pessutojr said:


> PS: Rocket Cellini v1. You have adjusted the Service Boiler pressure (to 0.75 bar). That has no influence what so ever on the brew pressure. Brew pressure should be around 9bar while pulling the shot. Leave the Service boiler pressure in the green zone, as that has an effect on your water temperature and steam pressure.


Thanks for this, very helpful. I'll put it back where it was.

I'll purge the grinder and see if it helps... but I've just done another experiment with a small blade/propeller grinder, letting it run as long as possible, to try to get a finer grind, and it was much better. Still not acceptable, but much better.


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## Rhys

I use my Isomac for brewed only. I'm guessing it's the same as mine but with better innards (mines plastic inside the burr chamber). It won't grind fine enough. Try a decent handgrinder or a used Mazzer SJ (depending on budget you can get better as well. The grinder is more important than the machine IMHO).

Bin the preground (you need a pressurised portafilter anyway to us this stuff).


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## cedriklizotte

Rhys said:


> I use my Isomac for brewed only. I'm guessing it's the same as mine but with better innards (mines plastic inside the burr chamber). It won't grind fine enough. Try a decent handgrinder or a used Mazzer SJ (depending on budget you can get better as well. The grinder is more important than the machine IMHO).
> 
> Bin the preground (you need a pressurised portafilter anyway to us this stuff).


Gotcha. Yes, everything's metal in the grinder. The guy who sold me the Rocket was adamant this is the stuff I need for espresso making. I'll let him know how I feel.

Thanks for the help. I'll go get some high quality coffee and ask the vendors there to grind it for me with their big machine. We'll see how it goes then.


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## Mrboots2u

cedriklizotte said:


> Thanks for this, very helpful. I'll put it back where it was.
> 
> I'll purge the grinder and see if it helps... but I've just done another experiment with a small blade/propeller grinder, letting it run as long as possible, to try to get a finer grind, and it was much better. Still not acceptable, but much better.


A blade grinder is useless as a indicator in this case . It's not always how fine a grinder can go but how consistent the size the bits of coffee are .


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## The Systemic Kid

Save yourself a lot of time and invest in some training. Either put out a request on the forum or approach a local coffee shop owner.


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