pcrussell50 wrote:4mm OD. And that's not just a second hand report. I've actually done it.

You will need some 1/8 NPT to 4mm quick connect fittings, if you are using the needle valve I think you plan to use. It's possible that a needle with BSP females instead of NPT females will give you more options.

-Peter

This is great thanks, Peter.

Recipe:
Dose: 20g
Yield: 50g } 2.5x
Time: 36s

Bean: S/O Ethiopian

I have been spending a lot of time profile shots and feel like this was one of the better shots. Any thoughts or feedback would be appreciated to getting even better shots.

Just a side comment on pairing the BDB with my new MonoCon grinder. Though only a week into using this grinder with my BDB, I must say I'm in heaven with the results so far. I'm several coffees in (from medium-dark to light roast) and I must say the pairing of these two machines is giving me so much room to experiment with, and experience the full depth of flavors my coffees have to offer. It seems the limit of grinding with the MonoCon is endless and coupled with the BDB's capabilities to play with preinfusion, I'm doing Slayer-style shots well into the 40 sec range without any evidence of choking the machine. I understand these are not "true" Slayer shots but getting closer is all in the taste. There is something to these long, slow shots, IMHO.

That's great, Bob. No, not quite true Slayer shots per se. The main difference being that the Slayer seems to build more pressure during the low water debit (pre infusion/pre brew) phase. So a little more forced wetting of the puck than you would get with the BDB at pp55. I worried about this at first, but after cutting a puck in half right after extraction, I did not see any dry spots. I should do a few more "puck autopsies" just for peace of mind. But my shots have been great, particularly some of the more obnoxiously light roasts, which really seem to like this technique.

-Peter

BaristaBob wrote:Just a side comment on pairing the BDB with my new MonoCon grinder. Though only a week into using this grinder with my BDB, I must say I'm in heaven with the results so far. I'm several coffees in (from medium-dark to light roast) and I must say the pairing of these two machines is giving me so much room to experiment with, and experience the full depth of flavors my coffees have to offer. It seems the limit of grinding with the MonoCon is endless and coupled with the BDB's capabilities to play with preinfusion, I'm doing Slayer-style shots well into the 40 sec range without any evidence of choking the machine. I understand these are not "true" Slayer shots but getting closer is all in the taste. There is something to these long, slow shots, IMHO.

A Monolith will make a huge difference congrats. I know I was blown away by my MonFlat w/ SSP burrs. The BDB is a very capable machine and it pairs quite nicely with a Monolith series grinder. The biggest issue I have now, is got going through pounds a coffee a week just to play with new grind/ machine settings

Guys,

Puck autopsies, internal surgery, and excessive coffee consumption...it totally cracks me up...and I'm totally with you!

pcrussell50 wrote:No, not quite true Slayer shots per se. The main difference being that the Slayer seems to build more pressure during the low water debit (pre infusion/pre brew) phase. So a little more forced wetting of the puck than you would get with the BDB at pp55.

So rather than being stifled by the limited pressure adjustment range using the BDB's pre-infusion settings, why not simply use the Hot Water Knob Trick™ to dial the pressure to exactly where you want it throughout the shot?

BaristaBob wrote:Guys,

Puck autopsies, internal surgery, and excessive coffee consumption...it totally cracks me up...and I'm totally with you!

This must be the ultimate hobby for those afflicted with OCD.

DaveB wrote:So rather than being stifled by the limited pressure adjustment range using the BDB's pre-infusion settings, why not simply use the Hot Water Knob Trick™ to dial the pressure to exactly where you want it throughout the shot?

The "trick" to a proper Slayer shot is to have high pressure with low flow. Using the water profiling knob limits both the flow and the pressure in a linear fashion. The water knob profiling is great for the back-end of the shot IMO.

The best way to achieve this as of now is to set the OPV to 8-9 bar, then set PD to 16 seconds (it takes ~15 seconds for my machine to go from 0- 2-bar) and PP at 85 respectively. This will help achieve a slow full pressure ramp up similar to a Slayer. The difference, however, is not being able to control the g/s at the same time. The best way to do this today is to use a chart (like below) to monitor your flow and then water knob profile your way back down the shot to get an average g/s between 1.5 and 2.5 based on the type of bean. I found lighter roast are great closer to 1.5 g/s and med are best around 2. I am not a fan of dark roast but I would think 2.5 would be best based on numerous test.



Here is all this in action:

eltakeiteasy wrote:The "trick" to a proper Slayer shot is to have high pressure with low flow. Using the water profiling knob limits both the flow and the pressure in a linear fashion. The water knob profiling is great for the back-end of the shot IMO.

The best way to achieve this as of now is to set the OPV to 8-9 bar, then set PD to 16 seconds (it takes ~15 seconds for my machine to go from 0- 2-bar) and PP at 85 respectively. This will help achieve a slow full pressure ramp up similar to a Slayer. The difference, however, is not being able to control the g/s at the same time. The best way to do this today is to use a chart (like below) to monitor your flow and then water knob profile your way back down the shot to get an average g/s between 1.5 and 2.5 based on the type of bean. I found lighter roast are great closer to 1.5 g/s and med are best around 2. I am not a fan of dark roast but I would think 2.5 would be best based on numerous test.

<image>

Here is all this in action:
<video>

Ryan,
So help me with this...I've been using the lowest power to pump setting of 55% figuring I want to keep the flow (in g/s) as low as possible during the preinfusion stage. My gauge typically will read 1 to 3 bars over 15 seconds of pi. Measuring the flow rate over that same time period at 55% gives me about 3g/s. The rest of my extraction flow at 9 bars works out to 8g/s. If I'm hearing you correctly, I should be using 85% power to the pump and then dial in with the water knob to more closely similate what happens during the Slayer prebrew stage?

Here are my observations from the video of the slayer shot posted earlier. There are 3 distinct stages during the shot, with 8 bars of pressure being the transition point between each stage: preinfusion, extraction, and declining extraction.

1. For preinfusion, the shot starts in pre-brew mode. Pre-brew has a flow rate of ~1.6g/s and resistance from the puck causes pressure to slowly ramp up. There is no pressure observed during the first 5 seconds. I assume this is how long it takes to replace the air with water in the portafilter.
Pressure reaches 1 bar around 15 seconds. Pressure reaches 3 bar around 18 seconds and the first beads are forming under the basket. Pressure hits 6.5 bar by 21 seconds when the first drops fall. Pressure reaches 8 bar by 23 seconds, marking the end of this stage.
2. Brew mode is engaged for the next stage. Water flow is set at 6.6-7.5g/s and the pressure increases to 9 bar (max). Max pressure remains constant for about 9 seconds and the extraction forms a single cone/stream about halfway through. Then, from 32-44 seconds the pressure falls to 8 bar as the resistance from the puck decreases.
3. Pre-brew mode is engaged again to facilitate the remainder of the declining pressure profile. Water flow is set to 1.6g/s and pressure continues to fall from 8 bar to 3 bar over the remaining 10 seconds of the extraction.

Just theory crafting here, but this is how I would approach a Slayer style shot with only a water modded BDB:
Prep: Configure pre-infusion PP to whatever % achieves 8 bar of pressure. (this is 68-69% on mine). Fully open the water knob.
0:00: Hold the manual button to begin pre-infusion mode
0:05: Adjust the water knob towards closed to start ramping pressure.
0:18: hit 3 bars of pressure (water knob should be mostly closed)
0:23: hit 8 bars of pressure (water knob should be fully closed)
0:24: release manual button to begin full pressure (9 bar)
0:45: barely open water knob to decrease pressure
0:55: end shot

Of course the exact timings, particularly from 24s onward, will vary depending on the beans. The long pre-infusion also means you will need to adjust your grind significantly more fine to compensate for how quickly it will flow during the extraction phase.

Following this process will give you a very low flow rate (maybe even lower than Slayer's) and zero pressure at the start of the pre-infusion allowing the puck to gently saturate. It will also mimic the slow pressure ramp up during the pre-infusion stage, the full (9 bar) pressure extraction and ideal flow (6.6-7.5 g/s) during the main stage, and the declining pressure and flow profile on the tail end.

It should be a pretty good clone, but there are a few differences. The water flow during pre-infusion will ramp higher than 1.66g/s as the pressure builds. I don't think this will impact anything because the puck should already be well saturated by the time we need to increase the flow rate. The goal of Slayer's slow pressure ramp up is to allow the puck to gently saturate with water before it has to deal with high pressure. Also the flow will be higher during the tail end of the shot, at a range of 3-6.5 g/s compared to Slayer's 1.66 g/s. This might have the largest impact because according to their theory, slowing down the flow rate towards the end of the shot allows Slayer to spend more time extracting the sugars. I am hoping this difference is minimized due to the fact that the puck is the primary flow limiter at this point -- not the artificial flow restriction (needle valve/glicuer).

For reference, Prima Coffee goes over some of the reasons behind the low-flow design that Slayer uses. This post by Jake_G talks through the forces at work behind a dry puck with a slow pressure ramp vs full pressure.