Congrats Ryan.

Remember, with a needle valve it's not pressure per se that you are controlling, it's flow. For example if you watch Shadowdax/Nicholas's Slayer shot video on YouTube you will see pressure go from zero to almost eight bar, non-linearly, with a fixed low flow needle setting. So don't fret/sweat what the pressure gauge is telling you except in gross. It is not for fine control in this space.

-Peter

Understood. I'm working on adding a piece to the knob assembly that will allow me to track the actual setting of the valve better, so I can rely on flow rates for repeatability, rather than pressures.

One question: how do you know what variables to adjust? The flow profiling adds so much control on top of dose, grind, yield, temp, time that it feels pretty unrealistic to only change one variable at a time when dialing in. Do you have any resources you've used to help with this process?

Thanks!
Ryan

Re: Silvia

blazarov wrote:Obviously BDB has much more sophisticated hydraulic design. Where does the needle valve come with this mod?

In the much simpler Silvia:

<image>

Where would the needle valve be? Between the pump and the boiler?

I have done some experimenting with diming the pump and my findings show that even at minimum pump power - the moment you open the 3-way valve, substantial water volume flows from the shower screen - presumably because of the residual boiler pressure. I am wondering if a needle valve between the boiler and pump will actually inlfuence that?

In order for the pressure gauge/sensor to read puck pressure it needs to be after the needle valve?

Bacek wrote:In theory in Silvia you could try to do it similar way by reusing hole in front of the group used on manufacturing to drill group canals. It's sealed with a screw. But then you would have to build your own needle valve in this hole. I'm not sure it's feasible, I guess it's not.

See Bacek's response above and recognize the manufacturing hole in the photos:


In the photos the hole that's numbered 1 is from boiler to solenoid valve, and numbered 2 is from solenoid valve to group head. I recon in order to connect both drilled holes (vertical at solenoid valve side of the hole #2 and angled at group head side of hole #2) a horizontal hole needs to be drilled on the front upper side of the group head body. And this hole is then plugged with the allen head bolt.


Silvia has a single stream of water path in brew mode.
Water Tank → Pump → OPV → Boiler → 3way Solenoid Valve → Group Head → Portafilter.
And after opv it has no big pressure dropping components like pre-infusion spring in a E61 group.
So if you put a suitable needle valve between OPV and boiler, you would have a proper flow control over the shot.

Pressure gauge:
In practice you can fit the needle valve to a Tee fitting, fit the pressure gauge in parallel to brew water, and fit the last end of the Tee fitting to the boiler. Since the machine doesn't have a component with big pressure drop you will be able to monitor the pressure with some non linear ∆P value (in function of flow rate). This might be enough to monitor the pressure to have pressure profiling.

The ∆P will be lower as you go closer to the puck. The above explained manufacturing hole is directly before the shower plate so it would give a pressure reading closer to the realtime brewing pressure.
You can try to fashion a cantilever tube that will fit to the thread of the manufacturing hole (this one will keep your machine intact and I assume avoid voiding the warranty), or if you have access to workshop tools you can enlarge this hole an tap it with a thread that lets you plug a pressure gauge brass fitting there.
Another alternative can be to tap a new threaded hole on top of the shower plate in group body and connect a pressure gauge that way. You can also drill another hole for a thermocouple to read brew temperature.

Although I definitely recommend the profiling mod, I think it's a good idea to learn how to repeatably pull great shots with a fixed pressure before you dive into flow profiling. Not only will it give you time to get comfortable with the machine, but it'll also give you a good baseline to compare against as you start down the profiling path. There's no need to undo the mod though, just leave the knob wide open and you'll effectively get "stock" shots.

Hi,
thanks for the thorough description and the idea about the manufacturing hole in the group head. However i consider it impractical due to the custom manufacturing required.

I have prepared a simple diagram of the Silvia hydraulics to help with the conversation:



My idea was to effectively throttle the flow between the pump and the boiler, while adding a second OPV between the pump and the needle valve to avoid building up unnecessary pressure when the flow is very restricted - see diagram:



If i understand the BDB hydraulics right the mod described here does the throttling between the boiler and the boiler (acutally the 3-way-valve) and the group head - marked with red dot in the stock diagram. Obviously this is better, but is practically achievable only on some machines - maybe this is one of the answers to my initial question - what makes the BDB a good candidate for a slayer mod?
I am wondering if my idea will work in practice and for potential undesirable implications such as:
- boiler filling/drainage issues? - honestly i dont think so. Am i wrong?
- ineffective flow control - its a fact that i will be actually throttling the flow for filling the boiler (input), not the flow from boiler to grouphead (output), but since its a closed volume i hope they should more or less be equal?

Hi everyone,

I've been reading this on and off and sorta following the thread. Wanted to chime in saying that I will be getting a Modded BDB from a HB member here, Johnny4lsu (thanks again btw).

Really looking forward to getting back to espresso as I had a CC1/Sette270Wi earlier but sold it because I wasn't fully happy with the espresso I was pulling. Now waith pressure profiling at my hands I look forward to pulling light roasts.

Johnny is a great guy and knowledgeable coffee man. And I'm quite sure he kept his machine well and most importantly, he used safe (scale free) water. You should, too.

Only other comment... The lighter you go, the more critical the grinder... and the Sette, good as it is for middle roasts, might not bring out the flavors you are looking for as you get lighter and lighter. But you can cross that bridge when you come to it. Let us know when you get your BDB and start playing with it.

-Peter

Yah, I've been chatting with Johnny on and off. He is a great man.

I sold that combo. I have the ForteBG now which I alligned after some chat with Baratza support. I had a Gaggia Classic that I restored for 2 days before it sold and I pulled some pretty okay shots with it. (Didn't bother TOO much with the temp surfing) I was thinking of getting a Kinu Pheonix though as a backup or even dedicated grinder. Not sure yet. I had a Lido 3 and after a few months didn't like the design so much.

On the Forte. i've been doing 8Q for brew and down to 3A for the espresso. I single dose, so once I want to go back to brew I vacuum out everything what I can from the top and then use about 5g on the coarse setting to purge any fines and the coming brew was just as accurate as it was before. No extra fines. I know everyone says that you should have 2 grinders for brew/espresso but it's been working not to bad.

BDB is coming Friday so Saturday I'll be able to pull some shots.

So, there was a delay in the packaging.

It came today and I was able to pull some shots. I immediately started profiling with the marks made by Johnny. I was very very happy with the shots.

4th one I was able to get a really tasty shot that I felt was better than what I tried at the Café. This was the monkey bite espresso from Bird Rock Coffee roasters in San diego. The 5th attempt it was already with a new bean, a washed ethiopian from Onyx. I didn't change the setting on my grinder and I felt like it was going to be overextracted. Shot time was 65 seconds and I thought it was going to be bitter and unpleasant. I made it into an Americano and was very pleased with it.

I've noticed that the profiling makes it very forgiving. When I had my crossland CC1 it's a bummer than if you grind to fine and choke the machine that's a puck wasted. With profiling you should be pre-infusing so you'll theoretically never choke out the shot right? Right now what I'm doing is keeping it low flow until I see beading then slowly going up until it gets to brew pressure where I go to full flow. Then once I'm reaching target weight I'm bringing it back down before turning it off.

What's a more organized or logistic way to pull shots. What should I be looking out for?

I'm already doing the basic prep stuff. RDT, WDT, tamp is with the Decent v2 tamper so it's consistent.

I've been doing the classic Slayer shot that Jake_G wore about, which I outlined here in an attempt to compile some recipes I've seen in this thread: https://github.com/qporzk/BDB-Slayer/bl ... ngShots.md

I haven't had a free day to do back to back shots to tweak this, but my Americanos have been tasty every day, so I feel like it is working well. I haven't gotten around to doing the killswitch mod yet, but am planning on it. If you want to add any recipes or suggest tweaks, let me know!