I have had my Monolith Flat now for several weeks. It was an 'upgrade' to my Baratza Sette 270 that I waited for with great anticipation for the 5 months it took to get here after ordering. The build quality surpassed expectations. It is just stunning.

My desire to upgrade began when I started down the single origin / light roasted coffee rabbit trail. I knew the 'sweet spot' for the Sette were medium roasted coffees and the reason I was getting channeling / dry spots must have been the grinder. I have watched and read about everything online on basket preparation and have had the Kafatek WDT tools (pick, grooming tool, LevTamp) for 6 months (I purchased them early to practice with and hopefully improve my Sette shots).

Weeks later using the Monolith Flat, I'm still not sure I'm having anymore luck pulling lighter roasted coffees than I was with my Sette. I have tried everything: VST and Stock Baskets; varying doses to create more/less head space; pre-wetting and no pre-wetting by lifting up the E61 brew lever partially and not engaging the pump; vigorous WDT; no WDT; some WDT; LevTamp and Espro Convex.

All of these marginally change the shot but it maintains its lack of uniformity and overall channeling. Basically the shots start out properly as beads across the basket, then as pressure goes to max a flow starts but there are a lot of dry spots. Generally the dry spots never fill in and you get this thin looking shot that sometimes starts squirting or gushing in places. Taste is usually nothing special.

I lay all of this down to ask a question of this community who speaks very highly of the Flat and its ability to produce 'end game' type shots. What am I doing wrong? Is it my machine (Profitec Pro 500)? The only variable I can think of I have not adjusted is brew pressure, which is at its factory setting of10 bar with blind disk (supposedly the way a vibration pump works, you lose 1 bar on coffee compared to the blind disk so 10 bar blind disk equals 9 bar on coffee). I see a lot of posts on here talking about lowering brew pressure to between 6-8 bar on modern coffee roasts. Even the DE1+ has a profile called 'trendy espresso' that has a low brew pressure profile. It makes sense that a lower pressure would greatly reduce or eliminate channeling as the water would have more time to evenly go through the puck. It seems like the bigger issue when going super low pressure is reducing the water debit which I'm not sure how you'd do on an E61. Changing the brew pressure on a Pro 500 is a PITA since you have to take the entire housing off so that's why I haven't tried that yet.

Thus, I wanted to create this topic to see if there is anything else basket prep wise I can do and whether or not it sounds like my machine is the issue, specifically a brew pressure that is too high for light roasted coffee. Most people on here raving about the Flat tend to have either a lever machine or a GS3 / Slayer which allow for a declining pressure profile (lever) or a controlled pressure profile that allows the barista to full saturate a puck prior to full pressure and eliminates channeling.

PS: Pulling espresso blends (Like Kaldi 700 for example) pull fine. But they pulled just as good on my Sette with much less basket prep work.

JayBeck wrote:All of these marginally change the shot but it maintains its lack of uniformity and overall channeling. Basically the shots start out properly as beads across the basket, then as pressure goes to max a flow starts but there are a lot of dry spots.

In my experience this is always caused by the lack of distribution in the basket. The coffee is not evenly distributed and it has air pockets left which allows water to find paths of least resistance, i.e. channels. Best is to work on your distribution. I use WDT for that. I have found lighter roasts hard to pull regardless of grinder and requirement for good basket prep is noticeably increased.

What is your WDT technique? I follow the same routine as Denis' video but my shots look nothing like his. I have also watched other online WDT videos and same result. I've tried doing a vigorous stir (like Socratic Coffee shows) and a gentle stir (like Denis shows on YouTube). Then settling the bed with a gentle tap, grooming tool, LevTamp. Not sure what else I could be doing?

I use vigorous WDT myself, I think Denis slowed down the technique on video so you can better see what's going on. Vigorous stir for me is most consistent, works 100%.

I forgot to write, but I have also found that some coffees are simply more challenging to pull and these are always light roasts. How did coffee that was included with the grinder pulled for you? Have you tried different coffees?

The Caffe Lusso that came with the grinder pulled fine. But that's an espresso blend like the Kaldi 700.

My first light coffee I ever tried and never was able to pull well on the Sette was Blue Bottle Opascope. I got a bag of that on week 1 of owning the Flat and went through the entire bag never pulling a decent shot trying all these various techniques. It did seem to pull slightly better using my Stock E61 basket over the VST.

I just finished a Kaldi Single Origin: Fair Trade Democratic Republic of the Congo Muungano. I must have bought the last of it as it isn't on the site right now. Nothing but a mess and bland espresso. It made a nice Chemex though. I guess I'll try a more vigorous WDT...but I see you are using a Cremina which is my thesis -- lever pressure profile may be why you aren't having trouble like I am.

Light roasts are just hard in general, I used to always struggle with the Vario, where the flat's advantage was being able to go much finer on these light roast coffees to get a proper extraction.

That said, since some light roasts require a very very find grind, it takes a lot more work to get the distribution right but still tend to channel very easily. Longer pre-infusions generally help with the channeling but I'm not sure how much control you have on the 500. Also light roast shots never look as pretty as something like café lusso on a bottomless portafilter, so don't be too concerned about the look. I've also found that light roasts tend to have a narrower band of parameters where you really get the coffee to shine. It's easy to get an ok shot, but sometimes it takes just the smallest adjustment to get more out of your coffee (whether this be grind, temp, yield, etc).

Have u fully broken in your flat yet? Have many pounds have you run through?

I found that with my flat, no amount of basket prep prevented channeling for certain types of coffee during the first couple weeks of owning it. However, after a couple months as the grinder became fully broken in, I didn't need to be as meticulous with basket prep. shots just always came out fine with just minor adjustments to grind setting to adjust flow.

I'd recommend you be patient with it for another 1-2 months. there's a reason why this grinder is so well loved.

*sigh* wrote:Light roasts are just hard in general, I used to always struggle with the Vario, where the flat's advantage was being able to go much finer on these light roast coffees to get a proper extraction.

That said, since some light roasts require a very very find grind, it takes a lot more work to get the distribution right but still tend to channel very easily. Longer pre-infusions generally help with the channeling but I'm not sure how much control you have on the 500. Also light roast shots never look as pretty as something like café lusso on a bottomless portafilter, so don't be too concerned about the look. I've also found that light roasts tend to have a narrower band of parameters where you really get the coffee to shine. It's easy to get an ok shot, but sometimes it takes just the smallest adjustment to get more out of your coffee (whether this be grind, temp, yield, etc).

Yes to preinfusion, both amount of water and soak time. I use it to compensate for my low end equipment quite nicely!

*sigh* wrote:Light roasts are just hard in general, I used to always struggle with the Vario, where the flat's advantage was being able to go much finer on these light roast coffees to get a proper extraction.

That said, since some light roasts require a very very find grind, it takes a lot more work to get the distribution right but still tend to channel very easily. Longer pre-infusions generally help with the channeling but I'm not sure how much control you have on the 500. Also light roast shots never look as pretty as something like café lusso on a bottomless portafilter, so don't be too concerned about the look. I've also found that light roasts tend to have a narrower band of parameters where you really get the coffee to shine. It's easy to get an ok shot, but sometimes it takes just the smallest adjustment to get more out of your coffee (whether this be grind, temp, yield, etc).

I've tried going finer but you get to a point you just choke the machine or barely get 10g in 30 seconds. Not sure about 60 second shots for ristrettos on a HX, LOL!

I know light roasts won't be as pretty -- maybe I should quit with the bottomless on them lol. Here is a video of Opascope being pulled. http://www.youtube.com/watch?v=XBH95YukiDw He doesn't use the bottomless unfortunately but that looks like more crema than I was getting. The LMLM here is reduced to 6 bar and has the smaller gicleur so my suspicion is that's why the shot looks better.

wai2cool4u wrote:Have u fully broken in your flat yet? Have many pounds have you run through?

I found that with my flat, no amount of basket prep prevented channeling for certain types of coffee during the first couple weeks of owning it. However, after a couple months as the grinder became fully broken in, I didn't need to be as meticulous with basket prep. shots just always came out fine with just minor adjustments to grind setting to adjust flow.

I'd recommend you be patient with it for another 1-2 months. there's a reason why this grinder is so well loved.

I'd say I'm about 5 pounds into it plus whatever Denis ran through it prior. Maybe a little more. I'm certainly grinding about 2 full steps finer than I was in week 1 (it came set to around 8 and I'm around 6 now).