# Consistent channelling



## drmarc (Mar 4, 2018)

I am getting consistent channelling on my Gaggia Classic at the 12 o'clock position in the basket (see pictures). It's really frustrating and I can't seem to get rid of it.

I am dosing 19.5g into an IMS 26.5 basket, and then distributing with a home made WDT tool before tamping.

I'm using a bottomless portafilter, and the pour always starts really nicely, coming through evenly with some lovely tiger stripes. This usually lasts about 10 seconds before it blows and gushes out.

Has anyone any idea why the channelling always happens at the 12 o'clock position?

Thanks


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## Mrboots2u (May 10, 2013)

A clip of the prep and pour is more helpful than post puck

Would be worth establishing if you have enough head room in our basket. So dose your 19.5 g put a 5p coin on top , put in pf. Take out pf, is the coin leaving an indent .

Is the indent we see at 12 o'clock post puck there too ?


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## drmarc (Mar 4, 2018)

Mrboots2u said:


> A clip of the prep and pour is more helpful than post puck
> 
> Would be worth establishing if you have enough head room in our basket. So dose your 19.5 g put a 5p coin on top , put in pf. Take out pf, is the coin leaving an indent .
> 
> Is the indent we see at 12 o'clock post puck there too ?


Thanks for the reply. I settled on 19.5g for this particular bean by using the coin check method, and there is no indent in the puck prior to putting the portafilter in and pulling the shot. If I was getting channelling in other places then I would be more worried about my prep, but it is always at the 12 o'clock position.


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## ajohn (Sep 23, 2017)

Looking at the deep rim around the puck you may have too much coffee in. Try a coin test 5p or 1p not leaving an impression on a tamped puck. If there is too lightly space when the grinds expand they get compressed even more. A little of that may help actually but too much and the pressure will find a weak spot or choke the machine.

Also do you need to stir up the grinds ? Some do it as they have read about it but it can make things worse. Light clumps that break up easily aren't a problem. Sufficient tamping will over ride them. Light tamping without some associated number with it can also cause grief.

I'm assuming that the tamp is reasonably level. If always low on that side ...............

John

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## MWJB (Feb 28, 2012)

drmarc said:


> Thanks for the reply. I settled on 19.5g for this particular bean by using the coin check method, and there is no indent in the puck prior to putting the portafilter in and pulling the shot. If I was getting channelling in other places then I would be more worried about my prep, but it is always at the 12 o'clock position.


It actually looks like there is channelling all around the perimeter of the puck? So, if your dose weight is OK (20g basket?), you may be way too fine.


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## El carajillo (Mar 16, 2013)

Is the brew head level ? Is the shower screen firmly fixed ? Dosing 19 gm's in a 26 gm basket, is it under-dosed ? too much head space ?


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## ajohn (Sep 23, 2017)

El carajillo said:


> Is the brew head level ? Is the shower screen firmly fixed ? Dosing 19 gm's in a 26 gm basket, is it under-dosed ? too much head space ?


I took the 26.5 to refer to the height of the basket. The rim of the puck looks weird but hard to tell if it sticks out or goes in from the shot also it looks vaguely domed.

John

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## ajohn (Sep 23, 2017)

The OP uses a dosing funnel that sits well into the basket (cheaper on Amazon). Did this start when you used this?

John

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## Stevebee (Jul 21, 2015)

El carajillo said:


> Is the brew head level ? Is the shower screen firmly fixed ? Dosing 19 gm's in a 26 gm basket, is it under-dosed ? too much head space ?


The 26 refers to the height of the basket, not its capacity. I think this one is 18g - 20g capacity


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## Inspector (Feb 23, 2017)

From the picture i can tell you are grinding too fine


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## drmarc (Mar 4, 2018)

Thanks for the suggestions everyone.

I'll have a play over the weekend and see how it goes


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## Microlot (Jun 22, 2017)

You may make a vid from the shower screen with water flushing through.


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