Help with extreme channeling - Page 2

Beginner and pro baristas share tips and tricks.
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#11: Post by emradguy »

Jake_G wrote:You should try it again.

Most folks who first try this don't go nearly vigorously enough. you really need to whip the grinds into oblivion. Otherwise your shot did not look bad...
And make sure to get all the way to the bottom of the basket. Afterwards, use the wire to try and even out the top third of the dry grounds, then smooth the rest of the way with your finger...and then tamp as level as possible.

I also would stress bean freshness, roasted within 2-3 weeks. There are reputable roasters in Hong Kong...I think...well, for sure in Taiwan...though I don't know any names other than Simon Hsieh's off hand.


#12: Post by disaster999 »

OldmatefromOZ wrote:Both the machines are re-badged Sunbeam, Aus brand.

You can not single dose these cheap domestic grinders and no amount of WDT will fix the poor grind quality.

Try keeping your hopper loaded at least half full likely you will be able to grind coarser as well and you will end up with more uniform grind.

The espresso machine should be able to pull pretty decent shots with a great grinder.
Wow thanks, I didnt know they were re-badged Subeam units. Good to know my machine should be able to pull decent shots

I kind of figured my grinder is the issue, but didnt know it was THAT bad. I dont want to keep the hopper full since I only make 1 drink aday and as you all know, keeping beans inside the hopper overnight is huge nono. cleaning it out, emptying the machine is a pain and wastes a lot of coffee too. I will definitely be getting a new grinder soon.


#13: Post by jrham12 »

One other thing to consider; Does your machine have an adjustable OPV? In the video, it looks like your pump pressure is around 12 bar.

On my Gaggia classic (new 2019 version), the OPV was non-adjustable and was set to about 12 bar for pods and a pressurized basket. As a result, I had a very difficult time getting a decent shot with a standard basket that didn't show channeling and spritzers everywhere. I was able to get it lowered a bit, but it was still high compared to the recommended 9 bar pressure. As a result of the higher pressure I think I had to try to grind finer than necessary to minimize channeling and get the shot times even close to correct. This led to most of my shots being bitter and overextracted. (at least to my limited tasting ability!)

So coupled with a lower quality grinder, it may be a double hit working against you...



#14: Post by disaster999 » replying to jrham12 »

I dont think my machine has an OPV. It tops out at ~14 bars and wont go any higher.

I guess thats another thing I dont get with extraction. The "golden rule" lately seems to be ~1:2 ratio of grinds to coffee @ 10bar pressure in 30s. I can never get that with my machine, If I adjust my grind to get 10bar on the brew head, my shot comes out super fast. If i adjust my grind to get a 30s shot, then I'll be at 12-13bars.


#15: Post by jrham12 » replying to disaster999 »

Just to be clear, the OPV is an internal component that limits the pressure that hits the coffee puck. Your pump is capable of pressures higher than that so the OPV acts as a relief valve to bleed off that excess pressure, usually back to the water reservoir. (I'm assuming your machine has a vibratory pump and not a rotary pump).

In order to lower the pressure at the puck, this OPV is adjusted so it opens at a lower pressure and limits the maximum pressure at the portafilter to about 9 or 10 bar when no flow is making it through the puck.

In the situation with my Gaggia (and your situation with your machine), my thinking is that you have to grind finer in order to create enough resistance to slow the flow down to keep the extraction within a reasonable time. If the OPV was set lower, you wouldn't have to grind as fine to get the same shot times. in my case, I suspect that the finer grind was causing most of my shots to be over-extracted and the higher pressure on the coffee puck was causing channeling to occur more often.

But that's just my thinking; keep in mind that I'm still learning as well! In any case, check your user manual to see if it says anything about adjusting the brew pressure...



#16: Post by disaster999 » replying to jrham12 »

Im pretty sure my machine doesnt have the OPV valve. Did some research and found on another forum someone actually retrofitted one onto my machine and they said they were able to dial in the pressure and all. Im all for tinkering and all, but I kind of have my eyes set on the Lelit MaraX (christmas present maybe?) so probably not gonna mess with mine for now.

I got some coffee locally freshly roasted on 17/3 and pulled a shot as soon as I got home. Didnt change my setting at, ground 19g of coffee, same distribution and tamp and all. The shot came out too fast lasting only 21 seconds with 2oz of liquid, but I can already see the most of the portafilter have coffee coming out and that made me pretty happy knowing that if I dialed in my grind/tamp some more I might be able to get a "normal looking" shot.

But then it got me thinking...could be because the beans are still fresh and releasing a lot of gas thus oozing to the sides as it comes out the holes, giving me an illusion of a more even extraction?? Given that I literally changed nothing about my technique or grind, or having fresh beans does make a huge difference?

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#17: Post by emradguy »

Having fresh beans does make a huge huge, that it is essential.


#18: Post by Maak »

HOW I ELIMINATED channeling.
1-This is JUST my experience on my equipment but it might help. I chose to experiment with ideas I heard of no matter what science says should or shouldn't happen in a puck. It's results that count. I only make 2 espresso's a day for myself unless we have guests. (And that won't happen untill covid19 lockdown ends)

2- Equipment:
- Mazzer super jolly custom modified for single dose.
- 1980's LaPavoni pub single group commercial machine (the volumetric model with large boiler and external pump.)
- Naked portafilter.
- IMs shower MA200NT
- IMS basket E&B B702TFH26 - 18-20g

3- Recipe. in this day of 2+:1 recipes with larger yields I'm a bit old school and go for the thick syrupy espresso. No milk ever. So it's currently 19.5 dose 28 yield in 28 seconds. I have found using a dose on the higher end of the baskets recommendation where the grounds just touch the shower actually gets the BETTER pour with less channeling. Obviously I can't see exactly what goes on in the portafilter during extraction but I see faint marks of the shower sometimes and always see a mark from the shower screw.

4-PROCESS: this seems long winded. I only make 2 a day so I don't care. It works for me. All these steps get me the best pour without channeling and the best espresso in cup to my taste.

A- fresh beans. You'll work out when the best period for your roaster is but for me curently it's between 2-9 days from roast. If your roaster won't date the roast go elsewhere.

B- I weigh the beans into a dosing cup as I don't want to waste. I spray the beans with a tiny amount of water with a small spray bottle to eliminate static (RDT). When doing this I see the grounds flying out of the grinder, loose compared to a little clumpier when I don't.

C- Grind. I won't go into dialing here but the jolly is a reasonable flat burr and I've done some modifications to enable less retention of old grinds and better grinding of a single dose without a hopper. I can put in 20g beans, get 19.5 grounds and flush out 0.5g grounds consistently.

D- I grind into a dosing cup. I've found for whatever reason, even with WDT it seems to be better with this intermediate step.

E- Weigh and adjust dose here. I POUR the grinds into the portafilter and find how I do this doesnt matter. However if I try to upend the dosing cup on the portafilter upside down and rotate as described here I get bad results. It seems to be something to do with the density of grounds at the bottom of the puck compared to the bottom. I'd love this shaking technique to work for me.

F- Hand tap to level the grounds. I use a dosing ring

G- WDT. I use a paperclip straightened out. I know what they say about scratching the basket etc but a toothpick leaves large hollows in the least for me

H- Tap the bottom of the portafilter on the bench. I find how this step is done, makes a big difference to the pour. If too hard you can feel when tamping that the top is soft and the bottom dense. Also after tamping sometimes the level grounds go unlevel. If this happens I scrape some grounds around a bit on top with the paperclip, otherwise the pour is uneven.

I- I use a wedge style grooming tool. I don't believe these tools really distribute well especially low down but they do give a great level puck to make level tamping easy with a regular tamper.

J- Tamping. I find with all this prep to this stage it's really easy to get the pressure right. You can feel easily when the compacting stops.

K- Pre infusion? My machine does not have pre infusion. I've been following the development of the decent espresso machine and on John's blog (one of the decent founders) he mentioned their staff have a competition for the best pour each day and someone sprayd the puck with cold water with excellent results and showed the difference in the spread of water hitting a pre wet puck vs a dry puck. I tried this and it was a game changer. I use the same sprayer I use for RDT. I hold the portafilter about 200mm away and move it about (to get even coverage) while I give it about 6 pumps on the sprayer. I've tried different amounts and this seems right for my sprayer and grounds. It's not a lot of water at all and it's a fine mist.. After trying and using all the other techniques this made the BIGGEST DIFFERENCE to the pour and channeling than anything!!!!!! While I do this I'm flushing the group

L-Make sure you don't slam the portafilter into the group as I've found this can unseat the puck in the basket.

M- Even though my machine is volumetric I'm always starting and stopping the pour with the manual button my machine has. I'm weighing and timing the pour.

OMG that seems like a lot of steps when separated out and written down but every time I remove a step the espresso is not as good. It has to be as good as the best cafe/barista I know can make it.


#19: Post by sprin001 »

I have always had difficulty with distribution and channeling. I bought a Pullman basket and tamper - this eliminated a significant amount of room for error in my espresso making and brought back a lot of enjoyment. The next upgrade was from a ceado e5p to a EK43 which made leaps of improvements.

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#20: Post by millmountain »

Maak, thanks for writing all that out. It gives me some good ideas for things to try in future.