From your prep video, I would suggest looking up a video on proper tamping technique.

I had a breville that would occassionally channel with old beans as the Breville's can have poor flow distribution also. But I have never seen your tamping technique used in puck prep. Also check your flow distribution ring (not sure of actual name) and shower screen and clean or replace to improve flow distribution.

I would agree with Fitz, I think you need to actually use the handle to tamp, and not press down on the edges of the tamper (that's what it looked like in the video). You'll get much better/even force by firmly grabbing the handle and pushing straight down. Just push until you feel coffee stops compressing, no more, no less. I know the smaller tamper that comes with the breville isn't the greatest, but I think changing up your tamping technique will help.

Echoing other people's suggestions that you should work on your WDT and tamping technique, though I don't think that's the root cause of your fast flow or crazy channeling issues.

Check out Lance Hendrick's video on how to WDT and he has a simple demo on tamping at ~9:38 of his video. You don't need to press super hard or like 4-5 times. Biggest things are 1) making sure your portafilter is level (which I can't tell if it is based on the angle of your video), and 2) ensuring your tamp is consistent (how hard you tamp doesn't really matter; just ensure you're applying the same, even pressure every time).

Are you grinding in two stages because the portafilter would otherwise overflow with the amount of grounds you're dispensing? I would suggest just putting the funnel on at the beginning, dose the entire amount, settle to compact, and then WDT.

Yes it does look like you needed to replace your grouphead gasket given the amount of water spraying from around your portafilter.

However, your shot is showing more than just channeling; it's gushing. Have you tried shimming your grinder yet? It's absolutely possible to choke the machine; I used own an Infuser (840XL) and could grind fine enough on my old Baratza Preciso to choke it.

Furthermore, it sounded like your pump gets louder at around the 10-second mark of your shot vid. Do you have pre-infusion set to the maximum duration (10 seconds), and then the pump ramps up to full pressure after that? I ask because the longer you pre-infuse, the faster your shot is going to flow afterwards once at full pressure. You can change pre-infusion length manually and programmatically; try pre-infusing for only 3-4 seconds to see if that will slow things down.

folks thanks a lot for all the time and effort put to help me.

I will try to answer all the questions one by one.

- I have no special reason to grind two stages. I just like it this way. I can do it all in one go but by my experience the final outcome is the same. I should order a cup compatible with the holder though.

- Yes I am worried about the group head gasket as well. Group head was replaced a couple days ago, the gasket should have been replaced but it seems it wasn't. Will order a new one.

- I didn't tried shimming my grinder yet because I have another one that goes a lot finer. I went as fine as I could just below the choking point and it didn't fixed the channeling. Besides, after disassembling and cleaning the built in grinder, the lowest setting is a lot finer and the pressure goes almost to the end of the espresso range, which is already too bitter for my taste. Do you believe it's still worth a try ?

- Regarding pre infusion:

The Barista Express has built in pre-programmed preinfusion - where the pump runs at a lower pressure - that runs for about 10 seconds; I have not found a way to change that in the programmed shot volumes, but you can modify the preinfusion manually on a solitary shot pull basis.

will try a manual shot with shorter pre infusion and report back.

- as for my tamping method... I read in a lot of places that it doesn't matter the force to be applied. I just found out by myself that using 3 fingers evenly spaced by 120 degrees (same place where portafilter locks are located) I could ensure the best leveling and still had enough force to push the puck all the way down. I do a final push in the handler just to make sure, but its more a double check and usually doesn't change anything.

To be honest at this point I am more concerned about a machine issue then my prep skills. It's true I have just started out, I might be doing everything wrong but it stills feels like an impossible task. I just bought this machine second hand and like I said the group head was replaced in the shop and the valve body was replaced by me. I can't help but believe there might be something wrong somewhere. Besides all the mess, final product is fantastic both in taste and crema. It just ruins the experience that I have to hold the cup in the air every time.

I hear you, but you should know that a machine can't make channels unless the water distribution is horrible in epic terms. A well-prepped puck will survive just about anything.

Follow Ira's guidance on WDT. I'm not sure what tool you are using, but don't do the side-to-side business. Keep everything fluid and circular in motion, starting down low near the bottom of the basket, working your way up. From there, tap straight down and tamp firmly, but no need to do a handstand on it. Just tamp straight down. Also, there is nothing wrong with using your fingers like you did, just don't worry about leaning on it after the fact. If you want to use your fingers, use them and be done.

Cheers!

- Jake

I am working on my prep skills like everyone suggested. In the meantime I did some research about my machine and it looks like channeling in the Breville Express is a common thing:

this guy "fixed" channeling by using a paper filter. down in the comments section someone says and I quote:

This is not fixing the channeling but covering it up[...]The water inlet is hitting the holes in the IMS screen and creating a water drill. I fixed this by using a thin Stainless steel plate above the shower screen.

then I found this:

I tried to dial in to this pressure while brewing, but found it impossible to get the flow slow enough when the pump kicked in. I saw somewhere else online that one trick is to hold the shot button in for the entire duration of the shot so that the pump does not kick in and send the pressure through the roof.

So my conclusion is there might be 2 things wrong with this machine that is causing channeling for me:

1) bad water distribution (it always bothered me that shower head has a single point water extrusion)

2) pressure going up to 15 bar per factory design

And as far as understand for the fixes:

1) can be fixed by upgrading the shower screen
2) can be fixed by forcing the machine to stay in the pre infusion phase for the entire shot duration

ifeghali wrote:1) bad water distribution (it always bothered me that shower head has a single point water extrusion)

2) pressure going up to 15 bar per factory design

And as far as understand for the fixes:

1) can be fixed by upgrading the shower screen
2) can be fixed by forcing the machine to stay in the pre infusion phase for the entire shot duration

You can also try a paper filter on top of your puck for 1).

2) really should be addressed with an adjustable OPV. Not sure if yours has any range of adjustment from the factory. I know the BDB does.

Also...

This is not fixing the channeling but covering it up[...]The water inlet is hitting the holes in the IMS screen and creating a water drill...

A water drill would fit my definition of water distribution that is "horrible in epic terms".

You need fresher beans.

Lots of tips offered, but no amount of tinkering will result in a "good" shot if the beans are too old. Get freshly roasted beans & wait 5 days. See if that helps.