A couple people posted numbers for their 100% pump power water debit back at the beginning of the thread. They ranged from 200-240ml/30s. (Mine was ~202ml/30s). 200ml seems to be the most common number, so your 180's is a tad restricted but not by a huge amount. Maybe your machine was naturally lower from the start?

pcrussell50 wrote:What I want to know from one of you stock BDB'ers is, what is your wide open water debit? I want to see if the water valve is slowing it down a wee bit on mine.

I'm getting 8 onces or approx 236ml in 30 sec at full pump pressure (started timing and measuring after pump ramped up). Got the same amount from the hot water valve in separate test.

Thanks for that tip. I ran another test and got 200ml/30s this time... Again, through the water needle, which is now routed through the solenoid and then into the group.

-Peter

Ok, I took a quick clip of the range from low debit, where I fluctuate the needle a little between super low debit and just regular low debit, and then slowly ramp it up to full open needle (something even Slayer doesn't do). The pump is running full power the whole time. No water exhausted through the tap. Eagle eyed viewers will see the IMS Competition shower screen instead of the stock one.
-Peter

pcrussell50 wrote: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

So I did a couple of "puck autopsies" last night. I sacrificed some medium-dark roast Papua New Guinea (I told the beans they were giving their life to preinfusion, blazing a new frontier in the name of science...they were brave!).

Puck number one. (prep: 18g in 18g VST basket, ground very fine using MonoCon ver.10, (produces 37g out in 40 sec.), WDT, distribution tool, tamp to 30 lbs.)

BDB set to 55% power and 10 seconds preinfusion at 200F, gauge pressure never above 3 bars, then shut-down machine to stop all water flow, remove pf immediately.

This is where it got interesting...tried to knock out puck onto wooden chop block to perform the autopsy...it just wouldn't come out! Banged it so hard, it came out in layers...no doubt a product of the distribution tool moving the top 1/3 of the puck around and causing this effect (a known fact). I would say though, examining the puck pieces that fell out and what was still in the pf...my feeling was that some of what was still in the pf wasn't completely wetted but hard to tell.

Puck number two. (same prep as puck one, however, eliminated use of distribution tool from the workflow this time)

BDB set to 55% power and 15 seconds preinfusion at 200F, gauge pressure never above 3 bars, drops starting to flow from bottom of basket, then shut-down machine to stop all water flow, remove pf immediately.

Better removal of puck this time (but still not easy) to perform the autopsy. Cut puck with razor blade to examine cross section for water saturation. This time it would appear that the puck was totally saturated at these parameters. See attached photos.


Just thought I'd share these finding. Comments welcomes for sure!

I think the conclusion from other preinfusion threads was that the puck achieves saturation when you see the first drop fall. Your mention of the distribution tool having an effect on the puck release is interesting. Does the timing of the first drop change based on whether you use the distribution tool?

Quick edit to add that I normally see the first drop between 13-18 seconds, depending on the pressure % and beans. Definitely well past the default preinfusion duration of 7s.

For the "Slayerlike" shots you guys are talking about, I usually ground fine enough that I would see first drops @28-30s before releasing the pre infusion button and letting the pump ramp up (where I used the water/profile knob to slow the ramp). 18.0g dose in 18g VST basket, RDT/WDT/distribution tool (no tamp).

Moving on from "Slayerlike" shots to actual Slayer shots (with modded BDB)* Here is a clip showing a Slayer shot extraction, pump running full power the whole time, through the needle valve: At about 34s (on the Breville shot timer), I open the valve to allow full flow, then in the last few seconds I begin closing it before cutting off the shot. It's easier when I am not holding the camera/phone in one hand.

*I call the needle valve modded BDB, Slayer shots instead of "Slayerlike", because with the needle valve, the physical process of pre infusion is not just similar to Slayer, it's exactly like Slayer.

-Peter

mrjag wrote:I think the conclusion from other preinfusion threads was that the puck achieves saturation when you see the first drop fall. Your mention of the distribution tool having an effect on the puck release is interesting. Does the timing of the first drop change based on whether you use the distribution tool?

Quick edit to add that I normally see the first drop between 13-18 seconds, depending on the pressure % and beans. Definitely well past the default preinfusion duration of 7s.

Hi Anthony,

It's true...logic says that the puck would achieve saturation once first drops fall, however, you need to make sure there is no channeling or edge cracks causing premature first drops, and that the bottom of the basket looks uniform with droplets forming across the entire surface. Then I would absolutely say the puck has reached saturation.

I'm right with you that almost all my coffees reach first droplets at around 13-18 seconds (at 55% power to pump). Peter and others are experimenting, and with flavor success, longer preinfusion times (approx. 30 sec.). To do this, I will need to follow suit and modulate the preinfusion flow with the water valve to slowdown the rate of water flowing to the grinds even more. I plan to experiment with this over the next few days with a coffee I love, but have been experiencing some bitter flavors.

pcrussell50 wrote:For the "Slayerlike" shots you guys are talking about, I usually ground fine enough that I would see first drops @28-30s before releasing the pre infusion button and letting the pump ramp up (where I used the water/profile knob to slow the ramp). 18.0g dose in 18g VST basket, RDT/WDT/distribution tool (no tamp).

Moving on form "Slayerlike" shots to actual Slayer shots (with modded BDB)* Here is a clip showing a Slayer shot extraction, through the needle valve:
<video>

At about 34s (on the Breville shot timer), I open the valve to allow full flow, then in the last few seconds I begin closing it before cutting off the shot. It's easier when I am not holding the camera/phone in one hand.

*I call the needle valve modded BDB, Slayer shots instead of "Slayerlike", because with the needle valve, the physical process of pre infusion is not just similar to Slayer, it's exactly like Slayer.

-Peter

This is great, Peter. Do you happen to have (or could you please take) a few photos of the inside so I can see how you wired everything up?

Thanks in advance!

Elta/Ryan, I'd be happy to...

But I just checked in for work and won't be home again until late Saturday night.

If it's any help I can describe it textually. Let me know.

-Peter