# Inconsistent Gaggia Classic performance



## adesignercallednick (Jun 20, 2012)

Hi Peeps,

Now I'm starting to time extractions, have invested in a grinder etc I'm starting to notice that my classic is giving very inconsistent results, despite using the same grind, beans, amount and tamp pressure.

For example this morning I made the first coffee of the day - dbl espresso, about 25 sec extraction time. 20 min later went to pull the same shot - 30 sec and much slower, then the one after that virtually choked the machine - almost as if the pressure had dropped and dropped or something.

As above I'd used the same grind setting, bean amount and tamp for each of these - does anyone with more experience of the classic than me know what this could be?

Thanks guys, as always your help is much appreciated!


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## jimbow (Oct 13, 2011)

That does sound quite inconsistent. If you don't mind me asking, how are you measuring the dose/amount of ground coffee? Also, are you measuring before or after grinding?

If you are not already doing so, I would suggest weighing the grounds using scales accurate to 0.1g. Even as little as 0.3g variance can make a massive difference.

Sent from my HTC One X using Tapatalk 2


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## chimpsinties (Jun 13, 2011)

Have you tried watching what happens when switching the brew switch on with no porta filter attached after it's been sat for a while? You'll see that some steam comes out, then some water, then it kind of stops for a sec, then the proper flow starts. Could this be your increased time of shot?


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## MikeHag (Mar 13, 2011)

1. Changes in atmospheric conditions. Temperature. Humidity. Steam from a kettle! They instantly change the beans and require grind adjustment.

2. Inconsistency of dose in the basket, despite consistent dose in the grinder. Retention.

3. Brew temperature instability. Varying temperatures dissolve different particles at different rates, which could affect flow. Need to find a consistent surfing routine.

4. Poor burrs


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## adesignercallednick (Jun 20, 2012)

Hi guys,

Thanks for replies so far.

In answer to the questions.

jimbow - Dose is a timed grind from the Eureka grinder I've got, so the 'measurement' is based on that - I've not been weighing beans etc - should I be?

chimpsinties - I will check this - it may be the reason for a delay but does not explain why it's progressively choking the more shots I pull.

I know I'm a bit of a newbie to all this - and doing a million things wrong - least of all I'm using the portafilter that shipped with the machine (the one with the plastic pressure reducing valve in it) - can someone point me to a link for a decent replacement one please?

I am thinking of finding a short course or session on coffee / pulling espresso shots, as I feel pretty ignorant at the moment (and disappointed in the results)

Does anyone know of any or could recommend some options (I'm based on the south coast, near Brighton).

Also people have talked about PID / temp kits for the Gaggia as a way of improving consistency - is this something you guys would recommend?


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## chimpsinties (Jun 13, 2011)

I'd get your basic technique and equipment sorted before you go looking at rather expensive toys like PID's. They're great but are only going to make a fine tweak to an already good technique.

The fact that you've got a pressurised PF basically nullifies anything we're saying because it works by building up the pressure in the basket before letting it out. This is appose to the puck of coffee forming a seal and building up the correct pressure. You need to replace that sh!t ASAP.

Get yourself a bottomless or normal double spout PF and a VST basket. I think HappyDonkey or CoffeeHit sell them.

What are you using as a tamper? Not that it really matters with the pressurised basket but it will once you get a proper PF and basket.


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## jimbow (Oct 13, 2011)

Try weighing the grinds that the timed dose produces (perhaps grinding into a container for easier weighing) before loading them into the portafilter. This will at least prove or disprove whether the timer is causing the inconsistency. Mechanical timers on grinders are pretty accurate but are occasionally inconsistent.

HappyDonkey are a good place for replacement baskets, portafilters etc. You might just be able to remove the black plastic and use an unpressurised basket with your existing portafilter.

Sent from my HTC One X using Tapatalk 2


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## adesignercallednick (Jun 20, 2012)

Thanks for replies...

I\m using a decent 57mm tamper - though might need a 58 with the VST basket I've just bought.

The basket sits a millimeter or so higher in the standard portafiter meaning it doesn't go onto the group head, so I need a new portafilter from happy donkey I think - Do you know if the VST i've got (18g straight edged) will fit in their double portafilter? I have a bottomless potafilter, but I can't use it without coffee spraying everywhere.

Will try weighing the does out to check they're consistent.

Will get the basics sorted first before PIDs etc....

Hopeless or what?!?!


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## Obsy (May 21, 2012)

I've got the Eureka Mignon and I no longer use the timed setting as it does vary with retention and the way the beans hop about when being ground as it has small burrs. If you weigh (using scales accurate to 0.1g) your beans before grinding then grind them using the manual setting and then do the same using the timed option, you'll see the difference and that transfers into the final shot (not for the better!). If you do want to use the timed option, you'll need to play about with the timer adjustment to ensure that the weight of beans put in pretty much equals the weight of beans coming out. If the Eureka is new, retention is a little bit of an issue as the burrs need seasoning and the grind is somewhat clumpy in the beginning and one of those clumps stuck at the top of the chute can weigh 0.5g which will affect the shot.

However, the main change in your shots initially will come when you get rid of the pressurised basket and black plug. Keep the same portafilter, just buy a double basket (non-pressurised) and when it arrives, remove the black plug and see the difference. Then when you have played around with the grinder and the new basket set up and are getting fairly consistent results, then I'd go for a bottomless PF otherwise you may end up with coffee soaked walls!

Good luck, it's a fab journey I think!


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## chimpsinties (Jun 13, 2011)

Obsy said:


> just buy a double basket (non-pressurised) and when it arrives, remove the black plug and see the difference.


Isn't the black plug in the bottom of the PortaFilter and the pressureised basket just the basket with a single hole in the bottom? Or are you talking about removing the plastic plug from the PortaFilter?

PortaFilter










Basket differences


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## Obsy (May 21, 2012)

The black plastic plug is what Gaggia call their 'perfect crema' device which is meant to be used in conjunction with the pressurised basket (ones on the right in the picture). The black plastic plug should be removed when using a normal basket (the ones on the left)


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