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Thread: Same filter basket, different group handle = different result?

  1. #1
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    Same filter basket, different group handle = different result?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi folks,

    I've spent the last week or so playing around with a bottomless portafilter on my Gaggia classic, to work on my technique. It's been very revealing and I've enjoyed the results.

    Anyway, today I popped the filter basket back in the regular portafilter, so that I could make two coffees at once. Lo and behold, it very nearly choked the machine up! Very little flow, jet black ink barely flowing from the spouts.

    My routine stayed exactly the same (dose, grind, temp surfing, tamping etc etc), only the group handle changed. I had three runs at it just to be sure.

    The regular group handle is standard Gaggia, the bottomless is from Coffee Parts, but very similar in construction where it counts.

    All I can think of is the regular group handle brings the basket closer to the shower head, thereby compressing the puck more? Perhaps I can think of a way to test this later.

    Anyone with any better ideas?

    Andrew

  2. #2
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    Is the group handle 'tighter' in the group? If not, puck compression due to differences in distance to the shower screen can probably be discounted.

    I think it highly unlikely that there would be a significant difference hydraulic resistance between the naked and the original, due to geometric differences in the flow paths, unless the bottom of the basket was very close to the portafilter.

    There is some who seem to think otherwise, however my thoughts are that subtle variations in the way the handle influences how you dose and tamp are likely at play.

    Might even be possible that the naked doesn't heat the basket/grinds as much whilst filling and tamping, altering the temperature of the water once the pour starts, altering the rate of extraction and thus initial viscosity (thus the hydraulic resistance of the puck and ultimately the flowrate ).

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    Thanks for your thoughts, MrJack.

    Quote Originally Posted by MrJack View Post
    Is the group handle 'tighter' in the group?
    It did seem tighter when I went back to the standard group handle, but I thought nothing of it. I assume they just locked into the group head differently due to slight manufacturing differences. Perhaps this wasn't the reason. I'll test this properly in a few days time.

    Quote Originally Posted by MrJack View Post
    There is some who seem to think otherwise, however my thoughts are that subtle variations in the way the handle influences how you dose and tamp are likely at play.
    I'm not discounting this having an effect, but the difference was night and day. We're talking 60mls of coffee with the naked vs 10mls with the standard. I'd have to be tamping and dosing wildly differently to create that effect, methinks.

    Andrew

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    Senior Member Dragunov21's Avatar
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    Could be lugs engaging at a different height, could be variance in technique (I don't know how long you've been making espresso), could very well be difference in tamping if you're not using a PF-holder to tamp (I hate tamping PFs on their spouts).

    There are those with a different opinion, but I hold that there can be no difference besides the above, unless your spouts are blocked. Even if you believe that there's an inherent difference between otherwise-identical spouted/naked PFs, this would be the biggest claimed difference I've heard.
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  5. #5
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    The 5c test should easily tell you if the basket is closer to the shower head.

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    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by TheBoneRanger View Post
    My routine stayed exactly the same (dose, grind, temp surfing, tamping etc etc), only the group handle changed.
    Not quite true. Your beans have also changed, as has the environment unless your setup is in a temperature and humidity controlled area.

    As coffee ages it goes through many changes. Those changes affect the brewing process. It is completely possible to see the changes you describe one day to the next due solely to the aging of the beans and/or changes in the environment. Making espresso with fresh quality beans is a constant dance of grinder adjustments to maintain the desired extraction.

    To be sure the reason behind the change in extraction is due solely to the different group handles would be to use both of them as close together as possible. Of course they will both need to be warmed up to the same temp. I would suggest doing 2 brews from each group handle repeated for a second day but reverse the order the group handles were used in the day before. If you see the same behavior over those two days then and only then would I be looking at the group handles as being the reason.


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    Senior Member Lukemc's Avatar
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    I'm going to suggest something which may be totally wrong in this case only because the same thing happened to me with a gaggia classic when comparing naked v standard portafilter.

    I was using a larger basket (triple, 18-21gm something like that)

    Really nice pour from the naked, barely any flow from the stock portafilter, same basket same grind same dose.

    The basket did fit in the normal portafilter, but must have been virtually flush with the bottom as i couldn't get coffee to flow properly from it..... I assumed that the basket must have been pressing down on the bottom of the portafilter when locked in to the group, blocking a bunch of holes.......

    May be worth looking at.....May not

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    Quote Originally Posted by Dragunov21 View Post
    Could be lugs engaging at a different height,
    That will only show the variance in lug height between the handles, but won't change the location of the basket relative to the shower screen - where the basket stops only changes due to variances in group seal wear or changes in seal thickness, which hasn't been altered. First spot I would look is in the spout for blockages.

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    Quote Originally Posted by MrJack View Post
    I think it highly unlikely that there would be a significant difference hydraulic resistance between the naked and the original, due to geometric differences in the flow paths, unless the bottom of the basket was very close to the portafilter.
    Quote Originally Posted by Lukemc View Post

    The basket did fit in the normal portafilter, but must have been virtually flush with the bottom as i couldn't get coffee to flow properly from it..... I assumed that the basket must have been pressing down on the bottom of the portafilter when locked in to the group, blocking a bunch of holes.......

    May be worth looking at.....May not
    I'm sure that could have some effect, yes.

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    Thanks everyone for your responses!

    I spent an hour or so this morning with the machine and both portafilters to try to get an answer on this one.

    I first checked whether the filter basket was close to the bottom of the portafilter (using blutack, if you're wondering). Nope, plenty of clearance.

    I then did what is commonly referred to as 'the ol' 5c piece trick' - no visual difference. However, during this step, I paid close attention to where each portafilter inserts into the group head, and how much pressure I was applying when inserting it (i.e. how far I was turning it to lock it in). It seems the bottomless inserts a bit after 6 o'clock, and the dual-spout inserts at more like 7.30...

    So after using the bottomless portafilter exclusively for a month or so, I'm convinced that what I was doing was trying to crank the dual-spout around to where the bottomless usually stopped, which was simply raising the filter basket too high, and likely compressing the hell out of the rubber seal.

    So I made a coffee using the dual-spout, and just lightly inserted the handle this time.

    Voila! A perfect pour!

    Thanks everyone for your responses, hopefully someone will find this thread one day to learn from my mistake!

    Andrew
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  11. #11
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    Great stuff! Good to see some well considered testing!

    As they say, the simplest answer...



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