My long and rambling path to preinfusion/pressure profiling - Page 40

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Jake_G (original poster)
Team HB

#391: Post by Jake_G (original poster) »

another_jim wrote:The Slayer and Jake's machine have needle valves on the cold water side of the boiler.
While I've no first hand experience with Slayer, I can say that my valve is 100% on the hot side. I think Slayer is, too. My valve literally replaced the gicleur in my group. It's as close to Bianca as Bianca is but I have a commercial solenoid TS group instead of a mechanical E61. In an HX machine, cold water valves would be a solid no-go with loads of flash-boiling in the HX and stalled thermosyphon circuits. My solution (which was fully detailed in design long before I knew of Bianca, but obviously not before Lelit began R&D) is pretty much identical to Bianca, except mine is a one piece valve instead of a separate needle and seat. I see no benefit in particular to either method, though it was easier to get the dimensions correct in my case going with an enclosed off the shelf valve than it was to try to marry an adjustable needle to the group cap and have it seat properly in an orifice mounted below...

In any case, I'm glad Bianca is giving this methodology some positive press. I'm loving the ease of control and massive flexibility I'm getting.
Wattbe wrote:I've been following this superb thread for some time and have had a go at replicating a few shots on my GS/3 MP. While I can control pressure and flow on the fly, I don't have any measure of flow rate.
I've heard that the Acaia brew master app can display real time flow rate on a bar graph but was wondering if that's what you're using or if there's an app/scale that displays it digitally in grams/second?
Any tips are appreciated.
Thanks.
Ben, thanks for chiming in. Im using nothing more than a $6 scale from Amazon and watching the numbers tick away to grab my rough flow rates. It's easier than it sounds. That said, Gábor has a great solution in the profiler. It's a pressure transducer and app that ties back to a Bluetooth scale that gives you charts akin to what Decent provides. Looking at the raw cost of appropriate pressure transducers, the cost is reasonable if not great, but it's more than I care to drop at the moment, so I just admire it from afar... It would be THE THING to get to have accurate measurement of flow and pressure throughout your pull.

Cheers!

- Jake

pcrussell50

#392: Post by pcrussell50 »

Jake_G wrote:While I've no first hand experience with Slayer, I can say that my valve is 100% on the hot side. I think Slayer is, too. ...snip...

- Jake
And another. My needle valve is also on the hot side... Though not because of my "rocket surgeon" analytical skills. More that it was most convenient that way.

I will say that big of a fan the GS/3 as I am and it's modding community, I'm glad that for this particular flow profiling project/experiment, I could simply put a needle valve in a single flow path and be done with it. Of course as Jake and I already know, you must choose one that allows you to go from low debit to full flow within a reasonable enough arc of turn to fit human wrist physiology.

-Peter
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Wattbe

#393: Post by Wattbe »

Jake_G wrote: Ben, thanks for chiming in. Im using nothing more than a $6 scale from Amazon and watching the numbers tick away to grab my rough flow rates. It's easier than it sounds. That said, Gábor has a great solution in the profiler. It's a pressure transducer and app that ties back to a Bluetooth scale that gives you charts akin to what Decent provides. Looking at the raw cost of appropriate pressure transducers, the cost is reasonable if not great, but it's more than I care to drop at the moment, so I just admire it from afar... It would be THE THING to get to have accurate measurement of flow and pressure throughout your pull.

Cheers!

- Jake
Thanks Jake, appreciate the info. I've had a go a gauging flow rate by looking at the scale as the shot pours. As you say, it is fairly intuitive.
As expected, I can see the flow rate accelerate quite quickly as the shot progresses, particularly if I've gone for a long, slow pre-infusion.
Out of interest, do you try to keep the flow rate roughly the same throughout the shot by reducing the flow through your needle valve as the puck erodes or do you allow the increasing flow to continue?

Cheers,

Ben

pcrussell50

#394: Post by pcrussell50 »

Wattbe wrote: Out of interest, do you try to keep the flow rate roughly the same throughout the shot by reducing the flow through your needle valve as the puck erodes or do you allow the increasing flow to continue?

Cheers,

Ben
I do exactly that. As I have always done on my levers, too.

-Peter
LMWDP #553

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Jake_G (original poster)
Team HB

#395: Post by Jake_G (original poster) » replying to pcrussell50 »

It's a bit of a dance for me, and varied based on roast level and what "works" with a given coffee.

When working with light roasted SO coffees, I follow Peter's lead. I grind fine, dose around 18g, based on the nickel test (flush shower screen bolt in my S20. In a GS/3, I think the bolt itself makes a great dose indicator, lock in, pull out and check) and preinfuse until the basket is wet across the bottom or even shut off the flow and bloom it if it's a coffee that I've had good success with doing so. I then open up my Sprofiling valve and watch the stream and scale. Everything is usually pretty stable until 18 to 20g in the cup. I then taper it off, trying to keep the 1g increments at a steady cadence into the cup until I hit my target brew ratio. I time my shot with grind adjustments, really based on hitting a target yield without blonding. And I adjust my time to seeing coffee on the basket by setting the water debit. Then I recheck the grind with reduced water debit. Light coffees really do well with 30 seconds to the basket wetting, darker roasts usually 15 or so.

With darker roasts, adjust things with the starting goal of tasting the bean instead of the roast. That means lower dose, cooler brew water and high water debit (6 to 8g/s) at first. Once I get the temperature right, I bring the water debit down until I need to tighten the grind up and I do so until I detect some astringent properties emerging in the flavor. Then I see if I can dose a bit more safely. Once I'm at this point, I'll profile the rest of the shot starting with a simple "back to pre-brew" setting like a Slayer and comparing that to a "flow profiled" shot as described above.

I'm at this point right now with MG and I'm struggling to find the sweet spot. Not that the resulting brew isn't sweet, it just isn't very interesting. Reading up on Josuma's blending literature (which is quite good), it seems to me that MG is a great base blend desperately looking for a highlighter SO to be added to it. It's sweet, syrupy, decadent and chocolatey, but there is no acidity to it. Like none. No hint of cherries, no blueberry. Ok maybe some fig... No floral aroma. Just a thick mouthful of 1-dimensional crema. Good. But quite boring... I don't think profiling is going to pull out any flavors that aren't there, but I'm not quite at the point where I can say what I should try adding to it to make it pop. I think it could be made truly wonderful with an acidic highlighter blend added to it in the right ratio, but which one?

In the meantime, I'll see if I can't find the right recipe for profiling, but they all seem very generic when all the flavor components are so similar. Do I want to emphasize the chocolate, or the chocolate? Do I want it to be thick and syrupy, or rich and heavy? Not a lot of options here. But none of them are bad...

Cheers!

- Jake

Wattbe

#396: Post by Wattbe »

Thanks to Peter and Jake for your replies - it's good to know how you guys are pulling your shots.
I had a go at reducing the flow rate when I observed a noticeable increase which occurred at the point Jake said it would. I brought it back to maintain a flow of approximately 1gm/sec which equated to a pressure of 3 bar at the puck. 17g in, 34 out over 55 secs which includes a 25 second, 3 bar preinfusion with a flow rate of approximately 4g/sec.
I'm not sure how objective my taste test was but I noticed less bitterness and a sweeter shot which is an encouraging start.
Thanks for the advice and I'll be following this thread with eager eyes!

Cheers,

Ben

pcrussell50

#397: Post by pcrussell50 »

Wattbe wrote:Thanks to Peter and Jake for your replies - it's good to know how you guys are pulling your shots.
I had a go at reducing the flow rate when I observed a noticeable increase which occurred at the point Jake said it would. I brought it back to maintain a flow of approximately 1gm/sec which equated to a pressure of 3 bar at the puck. 17g in, 34 out over 55 secs which includes a 25 second, 3 bar preinfusion with a flow rate of approximately 4g/sec
I'm not sure how objective my taste test was but I noticed less bitterness and a sweeter shot which is an encouraging start.
Thanks for the advice and I'll be following this thread with eager eyes!

Cheers,

Ben
These numbers are very similar to what I get when I do light roasts anyway, so I'd say you are definitely on the right track... Except that my pre infusion usually reaches 6-8 bar after about 30s. As with Jake, the darker the roast, the less duration I pre infuse.

And as with Jake, and going by the "rule of thirds" article written elsewhere here, (good read), it's usually by around 20g on the scale where I begin tailing back my needle to reduce flow and finish with 35g or so in the cup.

-Peter
LMWDP #553

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Jake_G (original poster)
Team HB

#398: Post by Jake_G (original poster) »

Merry Christmas all!

I thought I'd share a quick update on how things are going these days and take the opportunity to link to a few other relevant threads where interesting conversations are going down for future readers.

So, there are now quite a few folks hanging out in the "variable water debit" machine owners club, and I think it's safe to say that it is a very comfortable place to be. I mentioned earlier looking to find a highlight roast to augment my recent Malibar Gold shipment and I think I stumbled upon my favorite recipe this morning. But to get there I have to ramble. Sorry. Sue me :wink:

Ok, a few months ago I chimed in on PID flush or not to flush with my argument (that I still stand behind) that PID or not has nothing to do with flash steam on HX machines (and the subsequent need for "cooling" flushes) and that thermosyphon loop tuning is instead the way to lower your need to flush. This launched Thermosyphon tuning vs. group flushes for stable brew temperature, and lead to a pretty healthy conversation around balancing brew temperature and flushing requirements by adjusting the boiler pressure in concert with a properly-sized restrictor in the upper TS pipe. It was good stuff that culminated in me installing a 3mm restrictor and raising my steam pressure from 1.1 to 1.4 bar and having zero flash steam in the group. I did this like the day I got my 5 lb. order of Josuma Malabar Gold. So, without flash steam as an indicator of brew temperature, I've been pulling it blindly. I mention this "blind" phenomenon in this topic, and again here.

Fast forward to Friday afternoon, when I popped my thermosyphon tube off and made a new restrictor with a larger hole (~3.5mm). I didn't lower the pressurestat, but I now have about 7 seconds of flash steam at 1.4 bar and I once again have a frame of reference for brew temperature. All good things, though a may try 1.3 bar and see if I can get the flash steam down to just a couple seconds... all this makes me intrigued by the commentary occurring over in the Decent-izing a traditional DB machine thread, where Mario is contemplating mods to a very nice, very stable high end DB machine to make brew temperature (as well as flow/pressure) something that can be profiled within the shot. Quite an improvement from my "little" commercial HX machine, but very cool all the same.

So here we are this morning. I mixed up a batch of 55g JMG and 35g light-roasted Columbia Yellow Bourbon. 18g in and 37 out seems to be the literal sweet spot for this mix. I flushed to just the calming point, which is probably around 206°F, but I don't really care the exact temp. Just that I can repeat it at will... The grind was a tad tighter than I normally use (which is pretty fine already), and I did a very light Staub tamp after WDT, just to clear the rim of the basket and then nutated very lightly, just to get the outside of the basket densified. Nutating is the closest approximation to what a densifier does on a roller mill that I can think of in the Home Barista's tool kit, and seems to completely eliminate halo shots for me. This process leaves me with a light convex "muffin top" puck, that I then give a gentle tamp to flatten out the center. No grooming tool lately. Yes. The aforementioned process is exactly as tedious as it sounds... ok. Puck prepped, group flushed. I lock in and start the shot with a bonafide 1.5ml/s Slayer pre-brew and once flow is established ramp up to what would be a 6ml/s water debit. At least 35 seconds pass before 5g is in the cup. Once the scale starts ticking up at a rate of around 1 g/s (which was around 18g in the cup), I start pulling the flow back to keep it close to 1g/s. At 37g. The Sprofiling Valve was back in the pre-brew position and I ended the shot. I didn't time it, but doing the math, it had to have been around 70 to 80 seconds from start to finish.

The resulting shot was finally all the great things about Malabar Gold: Rich, thick, sweet, but with the added complexity and acidity of a light roasted Bourbon. Juicy apricot wrapped in mouthwatering, decadent chocolate and caramel. It was over too quickly...

Good stuff and a great way to ring in the Holiday season,

Cheers!

- Jake

pcrussell50

#399: Post by pcrussell50 »

Great stuff, Jake. My mouth is watering. For those of us with this capability, it's great discussing techniques, beans and recipes, as well as more scientifically technical cause and effect of employing the various tools we who have gone to the trouble of joining this club have at our disposal. As even legendary Jim over in the Bianca bench thread pointed out, this is pretty new stuff, running the whole shot through the same needle. Not even Slayer, whose current single group has been around for a few years now, does this. I for one have been sponging up everything I can, since I obtained this capability (under your guidance).

-Peter
LMWDP #553

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AssafL

#400: Post by AssafL »

Jake - Sounds like you are doing an admirable job cleaning filtration media!

Merry Christmas.
Scraping away (slowly) at the tyranny of biases and dogma.