We have a Breville Dual Boiler Coffee Machine, my husband even made a barista course to learn all about it.
But when we try to knock the coffee biscuit into a knock box, it doesn't work. It never comes out and if you use more force, the filter pops out before the biscuit (hope it's clear what I mean). So you need to get a spoon and scrape the coffee out of the filter (and avoid doing a big mess).

Does someone knows a trick or has an idea why it happens? I though, I use to much pressure to compact the coffee at the beginning, but according to my husband it's okay.

  • How long are you waiting between pulling the shot and knocking the portafilter? Jan 12, 2015 at 18:36
  • I didn't try different time, sometimes straight away, sometimes it can be a few minutes up to 10
    – Bettina
    Jan 14, 2015 at 3:43
  • 1
    A couple of other questions - are you grinding your own beans or buying a commercial grind? Also, how much coffee are adding to the basket? You might be over-dosing your filter. You can use the nickel test (place a nickel on top of the tamped coffee, put the portafilter on the machine, then remove and view - if the nickel is pushed way down into the coffee you have too many grounds and not enough headspace) to see. Jan 14, 2015 at 19:22

1 Answer 1


IF this is the machine you have, we're using the same.

Overdosing is the most likely cause. Please try to adjust the weight of your coffee dose. We've found that 20-21 grams is still OK for the double-shot.

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