eltakeiteasy wrote:Anytime. I just noticed you are in the UK this might be the same ones: https://www.amazon.co.uk/Abert-CF346-Ma ... B004EEKHKG

That one's similar but I don't believe it is the same. I found yours on several sites in Italy, but the post-Brexit shipping cost is prohibitive: ≥€40 as opposed to ~€5 for EU countries. If Covid ever recedes enough to allow me to resume my annual visits to Italy, I'll try to pick up a set up over there.

Indeed! Always more fun to pick up coffee stuff when traveling

Great, how do you like it so far? I personally like to raise the lever very slowly using the pressure gauge as a guide for light roasted coffee (I could see the value in slamming the pressure like that for medium to dark roasts to increase body).. have you tried using the gauge in that fashion yet?

No; haven't been using it for much beyond diagnosing a non-return valve issue lol!

I'll try your technique next time I pull a shot of Luna Bermudez filter roast.

OK, I tried your technique of holding back the lever to slowly ramp up the pressure - it works and is kind of fun/interesting! It's hard to say what the impact is, as I've not done any back-to-back comparisons. What are you looking for when you hold the lever back? What difference does it make?

Here is this morning's shot of Luna Bermudez (1:2 brew ratio, 5 bar PI, lever held back after release) - one of the best shots I've ever pulled, but I find I'm always saying that with this bean:

How do you ensure you can replicate same pressure profile shot to shot with this technique and machine?

If you hold back the lever then it's all muscle memory. The Londinium Compressa is very much an analog machine..

I haven't been on this thread in a long time, but I see the most recent discussion focuses more on the Compressa than the LR24. I've got a couple of questions/comments.

First, I'm wondering if anyone else besides me has not been able to use a Matrix screen with their Compressa. Mine literally just pops right off as soon as I lower the lever. I've tried several gaskets, both stock and the Cafelat alternative. These are gaskets that happily hold my IMS 35 and 200 screens, and my E&B screens in place on the same machine and also on my Andreja Premium (where I actually can use the Matrix screens - different gaskets of course).

Second, regarding the lever retard technique you guys are using. I've watched Tom's videos. The preinfusion looks slightly short to me for light roasts. Of course, in the videos, the puck looks well saturated when the level is raised. Retarding the lever is akin to lowering the brew pressure until the spring is release to act on its own accord. If you talk to Reiss or read his recommendations about PI pressure, you find he says to use about 1-1.5 bar for dark, around 3-4 for medium, and about 5-6 for light. While I didn't time it, per his recommendations, that PI looks about right for a medium-dark roast. Besides that, per Reiss, the Compressa runs hotter at higher pre-infusion pressures. Higher pressures and hotter temp both have the effect of increasing extraction. So does grinding finer. Certainly, we all have our own palates and taste preferences, and I advocate following your own palate instead of someone else's table of numbers, but let's say for a moment that he's spot on. Have you experimented with grinding finer and using high resistance baskets (like the E&B superfine), or addition of puck screens? Personally, I don't use puck screens (not sure why, but it's not something I don't even want to try) but I've been grinding very fine on my monolith Flat SLM and using the E&B basket with good success. My PIs for light roasts are about 20 sec (I count in my head, as I don't like using my Lunar for extractions on a shot to shot basis).

I am intrigued by the group pressure gauge, Tom. I might have missed it but, where did you source it?

Idfixe wrote:How do you ensure you can replicate same pressure profile shot to shot with this technique and machine?

His pressure gauge certainly helps, and I would guess it's very easy for him to be consistent. You could ask the same question to anyone who has installed a flow control on top of their E61 group. I was an early adopter, installing one on my Duetto as soon as Chris' started selling them, and found it extremely difficult to move that thing to the exact right spot at the same time every shot. Tiny movements yielded large changes in group pressure on the gauge.

emradguy wrote: First, I'm wondering if anyone else besides me has not been able to use a Matrix screen with their Compressa. Mine literally just pops right off as soon as I lower the lever.

I've got the Matrix installed now; using stock Londinium gasket. No issues with it popping off. I presume you seat it with a basketless portafilter first, then lock it in with portafilter with basket installed? FYI: No noticeable difference to me in extraction between it and the IMS/Londinium 35U. I think Matrix might have more value to pump machines with 3-way valve.

emradguy wrote: Have you experimented with grinding finer and using high resistance baskets (like the E&B superfine), or addition of puck screens?

I'm using the E&B 18g superfine basket for light roasts, including the Luna. I always grind beans straight from freezer, which seems to have the effect of a slightly finer setting. For these Luna beans, I have my Monolith Connical set at 0.5 - near its finest setting. Not sure I could go much finer, at least until my Max arrives in April . Reiss has advised 15 sec to first drop for light roasts, and I'm pretty close (13 sec). Maybe I'll take it down to 0 next time. PI pressure at 5 bar for these shots. In any event, I'm getting amazing results with the Luna beans, but don't have enough time using the lever-retard method to understand its impact.

emradguy wrote: I am intrigued by the group pressure gauge, Tom. I might have missed it but, where did you source it?

I made it, with inspiration (and lever group cap source) from @Madman13.

Lever group cap and PTFE washer from espressoparts.com, stainless gauge from Wika, 1/4 inch stainless tube and fittings from Amazon. Plus pipe cutter/deburrer, pipe bender, 1/8 NPT tap from various sources. Fun little project; I've got an even cooler one in the works