Coffee making - the perfect grind!

I have a Breville dual boiler coffee machine, BES920, which is now a year old - it replaced the same machine which we had for 6 or 7 years so I consider I know what I’m doing and what to expect.

I was always happy with the what the first machine produced - coffee tasted good and the leftovers (for want of a word) would fall out of the portafilter in a nicely formed, relatively dry shape - easy to dispose of. The newer machine makes quite different coffee, (though the taste is OK), very sloppy leftovers which can’t be disposed of in a knock box (goes in all directions) and which doesn’t seem to affected by brand or grind.

I complained to Breville early in the piece - we had numerous phone calls discussing how things should work and the fact that the machine never got anywhere near the required pressure (between 8 and 10 on this machine) on the pressure gauge and the machine was replaced - the replacement isn’t any different.

So I think my questions are quite specific -

  1. what determines the consistency - dry and formed OR sloppy - of the leftover coffee? I would think the grind would affect this but this doesn’t seem to be so.
  2. what should the should the pressure ideally reach? The needle always wavers just below the ‘8’.

Any suggestions about what I can try will be welcome.


@RebeccaCiaramidaro from Choice may wish to respond.

I suspect you are familiar with the normal tips.

From personal experience (Sunbeam EM7000) the grind and quantity are closely related. If you go coarser try putting in more coffee and vice versa. 9 bars is often cited as ideal in a general case assuming your gauge is calibrated. A fine grind might get you 9 bars but if there is not enough coffee in the basket the puck will float up and stick to the shower screen or be muddy. If that happens go slightly coarser with more coffee and a firmer tamp to maintain the pressure.

There are some who suggest putting a small coin sized object (or clean coin) on the top of you coffee, inserting it into the machine, and removing it, should yield an indentation of the coin. Alternatively there should be evidence of the screw/indentation of the shower screen. If it does not you are not using enough coffee regardless of grind.

If you still have your old machine parts compare the portafilter and basket. From experience even different hole patterns on the coffee baskets can have subtle effects and manufacturers change some things just because they can or because a different process might save a cent in manufacturing costs.

I have a Eureka Mignon grinder, not so well reviewer by Choice, but instead of click stops it has an infinitely variable adjustment, and as the humidity or temperature changes a nudge one way or the other has worked magic.



Hi @Rel and @PhilT

I’ve spoken with our tester and the most important thing to play around with would be the quantity and grind that you’re using. We have experienced similar issues during testing but once an extra gram or so was added it fixed the pressure issues. The only thing to be careful about is that the extra coffee grind might cause the coffee to be burnt as its being extracted and lower the taste quality of the espresso.


As for your sloppy pucks, it’s usually adjusting one of your variables…amount of coffee or grind size (whilst keeping your tamping pressure consistent). This is turn will affect your pressure reading. So if you have way too much coffee in there and it is a fine grind, the resistance will be high and your machine will battle to get any water through it. I had a similar problem and found I wasn’t using enough coffee. And just remember to vary one element at a time.
Watch James Hoffman on Youtube…very informative! He likes to precisely weigh his coffee so he has that one variable under control.

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What makes for a “sloppy” is the gap between the top of the tamped surface in the basket in the portafilter and the shower rose of the group head. If it really bothers you, get some coffee scales and start with your regular shot - weigh it. Then, add more coffee (say, 0.5gm). Keep re-doing the shot with additional increases in shot weight until the sloppy puck disappears. At this point there will be no gap between parts mentioned earlier. Now, two words of warning–if you overfill the basket, when you lock in your portafilter you will add pressure to the shot (compressing further an already tamped shot), and you won’t get your desired “mouse-tail” pour. Also, as you incrementally add coffee to your basket, you will probably have to back off the grind as it will become too fine for the shot volume. Coffee machines vary but your instructions should tell you the time and volume for a good pour. A barista using an E61 group head, (cafes and high-end home machines) aims at 30 seconds for 30 mls. (Double shot - 60 mls in 30 seconds). This gives that mouse tail pour. Experiment to see what ideally suits your machine but be in control of your variables (weigh of coffee in the basket @ what grind). Hope this helps.

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Thanks Phil.

You’ve reminded me what the leftovers should be called - puck ----

My questions were

So I think my questions are quite specific -

  1. what determines the consistency - dry and formed OR sloppy - of the leftover coffee? I would think the grind would affect this but this doesn’t seem to be so.
  2. what should the should the pressure ideally reach? The needle always wavers just below the ‘8’.

Re 2 above - the gauge shows a black section which seems to be
This machine comes with a gadget which trims the top of the dry coffee so it isn’t overloaded and that means that the pattern of the shower screen won’t appear - to the extent that if it is overfilled the coffee dribbles out and produces a very small amount.


I hope this reply can be seen by all those who responded - PhilT, Suzique, Rebecca and BassaJack, thanks for your suggestions, it will take some time to try all those suggestions and see how they go. Much appreciated.


A lot of solutions for you to try here Rel but for what it is worth the puck is very much affected by the grind quantity, the tamp pressure and the particle size of the grind.
You need to tamp with the same pressure each time. It should be reasonably forceful because the density of the grind is what creates the back pressure on the pump and gives it the correct extraction. In simple terms the pump has to push hot water through the grind and that creates the pressure that you see on the gauge. Too low a density and the water will flow through easily giving low pressure on the gauge and a sloppy puck.
Check your contents container because Breville provides a stainless levelling device. It is basically a scraper to allow you to get a uniform amount in the cup after it has been tamped.
If it is still too wet the grind setting will need to be adjusted inside the machine. Remove the hopper and beans, grasp the stainless wire grip and turn it to unlock and remove the inner teeth of the grinder. Clean the inner and outer teeth (I use a stiff paint brush). There is a grind adjustment setting you can change before you reassemble it. It enables you to go finer or more course. It could also be that your grinder teeth are somewhat clogged which will also have an effect.
When you get it all correct you should see the pressure rise to about 3/4 of the max setting on the gauge. The puck will finish dry.
I have found that changing beans to a new brand will sometimes require a the grinder to be readjusted.
I realize that there is an external wheel to change the grind size but I have found cleaning the teeth and making the internal adjustment is the best way to go.
There are some good YouTube videos on how to do all this. It is not difficult.

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Thanks for your suggestions Mal. This machine doesn’t have its own grinder and I have stopped using the grinder I have because I don’t think I can adjust it to grind fine enough, though it has instructions about how to make it finer it didn’t work. I get my coffee ground from a good, reliable source (35 years in the business) and use it fresh.

Yes, I use the levelling device and, as far as possible, tamp with the same pressure - though hard to be exact but likely to be too much pressure rather than too little.

Anyhow we’re just about to go off in our caravan, (where we use an espresso maker) so I will come back to this in a couple of weeks. Then I will start again, one step / change at a time and see if I can get it right. I’ve now had this machine for 18 months and I’m becoming very disillusioned.

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What model is it? Most grinders can get fine enough for Turkish and espresso should be about mid-setting +/-.

Was that shimming the burr wheels or relocating the collar in its track? Either should result in a noticeable difference, even if not enough at the first go, noting some entry grinders are sloppy (imprecise) no matter what.

FWIW if I leave ground coffee for more than a few minutes it starts drying out. Do you buy it fresh every morning and promptly use it? If I even leave whole beans in the grinder hopper for a few days they will noticeably decline.

Using pre-ground coffee could be the or part of the problem. Some machines are more tolerant of it; some thoughts to prove or disprove that possibility:

  • if you have a dual wall basket have you tried that? If you do, and it improves your shot I suggest you revisit your grinder, and/or
  • buy a small bag of the highest quality ground for espresso machines you can get at your grocery (Vittoria Espresso; Lavazza Qualita Oro or their Barista line; or Illy Espresso). If that improves your shot when first opened, first coffees, whether or not it is acceptably good, you have likely identified the problem as being your beans and grind.

I look forward to hearing how you go, and happy travels.