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Going insane with channeling, pls help!

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  • Going insane with channeling, pls help!

    I'm wondering whether someone might be able to diagnose this annoying channeling problem I've got. It's driving me crazy.


    I'm using a Unico Splendour machine with a convex 58mm tamper. FWIW I'm using Cosmorex Rio Gold beans which I grind at home using a Rocky doserless. I'm pretty sure the machine zeroes at 8 (out of 40) and I grind a 10, (but have also tried at 9). I weight 22g (sometimes 21g) into the portafilter and use the tamp to push the coffee down and it resides with normal pressure just under the raised 'lip'.

    BUT, I always get a channel hole at the same position, at 12 o'clock or 12:30 (see diagram). The consistency of the channeling occurring AND its position has to be something systematic. Any ideas? It's making great coffee taste not so great
    Attached Files

  • #2
    Maybe try and drop the dose back a little and go finer. 22grams maybe just too much and there is plenty of info out there suggesting that over dosing can lead to channeling. Just a thought

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    • #3
      Have you tried the nutating tamp technique (see post on this)? Helped reduce channeling for me.

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      • #4
        Agreed, I've found that technique is great, especially noticeable with a naked handle

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        • #5
          As it's always in the same position perhaps it's a machine issue, rather than technique. Maybe the screen is less clogged at that point?

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          • #6
            My suggestion is that once you have done all your dosing and tamping etc, rotate the basket in the handle 90 degrees before you lock it in to the machine.

            That way you will be able to tell if it is you or the machine that is causing it to channel in that spot.

            If the channeling is still at the ~12:30, it could be something to do with the machine. Check the showerscreen for blockages, fouling, etc.
            If the channeling moves when you rotate the basket, then it's time to look at your dosing/tamping technique.

            Edit: Further to the above, when you lock the handle into the machine, try and take it out again before you make a shot and inspect the coffee to make sure it hasn't impacted the showerscreen before you brew. If the dose is too high and it hits the showerscreen before it even gets wet, this can lead to channeling too.

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            • #7
              thanks all, these are all great ideas for me to try. I will do so and reply back when done.

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              • #8
                ....can't change the entry point of the portafilter due to groves on grouphead

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                • #9
                  Turn the basket

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                  • #10
                    ah so....!

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                    • #11
                      I had the same problem when I started out with my silvia, after reading a whole lot of posts I worked out that I was putting just a touch too much coffee in the PF. When it gets wet it swells and hits the nut on the bottom of the shower screen where the hot water comes out, that causes the water to squirt out thru the crack. Looking at your pic I think it is similar to what I was getting.

                      Instead of the stated 22 grams for my 22gm basket I use 21 grams, makes a BIG difference.

                      Please let us know what works for you.

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                      • #12
                        I used to have a channeling issue with lower doses until I was told to try and tamp harder. The problem stopped. Lower dosages require more resistance to the water flow and pressure, so this helped me a lot! Higher doses can be an issue too, the relativeness of the grind plays a major factor.

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                        • #13
                          Are you sure it's channelling and not just a bit of grinds that sticks to the same place on the shower screen each time?

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                          • #14
                            Perhaps you are just dosing more to the front of the basket? Try rotating the portafilter 90º when you fill it, and see what happens.

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                            • #15
                              OK, an update on subsequent attempts.

                              1. Used 21g + nutating method + coarser setting(10). This visually reset the coffee a good 2-3mm below the lip than when not using nutating method. Result: shot channeled in same position and pour was on the slow side. Interestingly I did get some oils on the periphery of the crema that I don't normally get. But in short it was undrinkable due to channeling.

                              2. Used 20g + nutating method + coarser setting(10) + 180degree turn of the basket. Result: channel in same position!! pour was too fast, very watery taste and undrinkable.


                              I will next try finer setting 9, but not sure of grams at this stage, maybe 21g as a start. Also need to dabble with a harder tamp as pnormal kindly supplied.

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