On Edit... We are already there. Not only Slayer shots but beyond, so if you are wanting to skip the theory and development and learning puffery, and jump ahead to the upshot go to post...161 on page 17: Breville Dual Boiler "Slayer shots"?

RE "Slayer shots" from the BDB...

Slayer folks, please contribute and correct any mis statements of fact I might have...

Ryan already knows this, but on a Slayer, you grind super fine and do a looong slow pre infusion until that fine tight puck finally shows drips, then you hit it with the brew pressure. We can do this with the BDB by setting the desired "water debit" in the pre infusion menu, the press and hold the "manual" button, which holds it in pre infusion (pre-brew in Slayer lingo), until you release the "manual" button, which then turns on full pump power. As with the Slayer, you hold the machine in pre infusion with "manual" button until you get your first drops, then release it, and it goes to full pump pressure and finish the shot. Unlike the Slayer (and someone correct me if I'm wrong), you can use the BDB's "profile knob" to slow down the full pump output if you feel you need to. Not sure if the full-brew position on the Slayer V3 paddle will modulate flow, or if it's just "on", (I think Slayer is up to V3, but I don't follow aggressively).

Ok, so that's the primer. On the Slayer, there is a needle valve you can set to control flow while in pre infusion (Slayer calls it pre-brew). It is set default to about 60ml/30s. Some users screw it down to about 50ml/30s. This is called in the jargon, the "water debit". So I decided to test my BDB at the lowest pre infusion output. I couldn't get my water debit quite as low as Slayer. At pump 55, which is as low as it goes, after five pulls, I got a nominal, 68ml/30s. It varied between 70 and 65 over six tests. Pretty consistent. I'd love to know if the Slayer is more consistent. Wouldn't be surprised if it is about the same. So, my BDB couldn't get a water debit quite as low as Slayer. BUT, I'm just not sure that such small differences during the pre-brew phase make first-order negative differences in the cup. I'm not discouraged in the least, to be honest. My shots sure are tasting good. Really good.

-Peter

Following this thread closely!

pcrussell50 wrote:RE "Slayer shots" from the BDB...

Slayer folks, please contribute and correct any mis statements of fact I might have...

Ryan already knows this, but on a Slayer, you grind super fine and do a looong slow pre infusion until that fine tight puck finally shows drips, then you hit it with the brew pressure. We can do this with the BDB by setting the desired "water debit" in the pre infusion menu, the press and hold the "manual" button, which holds it in pre infusion (pre-brew in Slayer lingo), until you release the "manual" button, which then turns on full pump power. As with the Slayer, you hold the machine in pre infusion with "manual" button until you get your first drops, then release it, and it goes to full pump pressure and finish the shot. Unlike the Slayer (and someone correct me if I'm wrong), you can use the BDB's "profile knob" to slow down the full pump output if you feel you need to. Not sure if the full-brew position on the Slayer V3 paddle will modulate flow, or if it's just "on", (I think Slayer is up to V3, but I don't follow aggressively).

Ok, so that's the primer. On the Slayer, there is a needle valve you can set to control flow while in pre infusion (Slayer calls it pre-brew). It is set default to about 60ml/30s. Some users screw it down to about 50ml/30s. This is called in the jargon, the "water debit". So I decided to test my BDB at the lowest pre infusion output. I couldn't get my water debit quite as low as Slayer. At pump 55, which is as low as it goes, after five pulls, I got a nominal, 68ml/30s. It varied between 70 and 65 over six tests. Pretty consistent. I'd love to know if the Slayer is more consistent. Wouldn't be surprised if it is about the same. So, my BDB couldn't get a water debit quite as low as Slayer. BUT, I'm just not sure that such small differences during the pre-brew phase make first-order negative differences in the cup. I'm not discouraged in the least, to be honest. My shots sure are tasting good. Really good.

-Peter

My BDB had a much higher water debit:

During pre-infusion at 55% - 250 ml/min == 125ml/30s
During pre-infusion at 75% - 370 ml/min == 185ml/30s
Regular flow - 400 ml/min == 200ml/30s

Great data, thanks.*

The wildcard I forgot to mention with mine is that I have a commercial brass OPV (set to 9 bar max on a blind filter, BTW). It wonder if even at pressures way too low to trigger the OPV, it's introducing an orifice effect, that reduces my water debit? I was PM'ed by another HB'er who reminds me that cracking open the "profile knob" even a little bit, drops the water debit quite a bit. I did not do this in my testing.

It would be nice if we could collect some more ml/30s water debits from other BDB users.

*a bit off topic, but are you able to mimic Slayer shots on your GS/3? If so, have you done any water debit experimentation on it? If so, what kind of numbers are you getting?

-Peter

gr2020 wrote:My BDB had a much higher water debit:

During pre-infusion at 55% - 250 ml/min == 125ml/30s
During pre-infusion at 75% - 370 ml/min == 185ml/30s
Regular flow - 400 ml/min == 200ml/30s

Did you also use the water knob aka profiling knob in addition to the pre-infusion?

I was able to get much lower numbers combining both. I will take another video of me using the profiling knob and capturing the group head together to give you a better understanding: http://www.youtube.com/watch?v=IL6N1Q8hu30

eltakeiteasy wrote:Did you also use the water knob aka profiling knob in addition to the pre-infusion?

No, those numbers were with the hot water tap completely closed.

Try the water knob mod and leave it open. That is why your numbers are so far off from Peter I believe. Peter correct me if I am wrong.

Remember that a Slayer will hit full brew pressure in pre-brew with a blind basket or puck with appropriately finely ground coffee. The water debit is low, but the pressure potential is great. This is critical to how a Slayer transitions from pre-brew to brew.

I hope a Slayer owner chimes in here in case I am speaking incorrectly.

Cheers!

- Jake

pcrussell50 wrote: *a bit off topic, but are you able to mimic Slayer shots on your GS/3? If so, have you done any water debit experimentation on it? If so, what kind of numbers are you getting?

I think it depends how you define "slayer shot". But before I get to that, some observations.

Wide open water debit is about 500ml/min (or a touch higher), and I can make it go literally as slow as I want, below 1ml/sec.

What is unclear, and I haven't tried to test this exhaustively, is whether at those very slow flow rates (like 1ml/sec), if pressure will build when resistance is encountered. There is a good half inch of travel on the paddle between the position when water starts to trickle out, and the position where it will hold say 3 bar of pressure against a blind basket (or a coffee puck). And the water debit with no resistance at the 3-bar position, for example, seems to be about 350 ml/min (which I only mention to illustrate it's a significant movement in the valve).

So all this is to say:

1. I can run a shot with as long of pre-infusion as I want, pretty much

2. I can hold the pressure against the puck constant any any level from around 1-9 bar (assuming sufficient resistance by the puck)

3. I'm not entirely clear if the above means I can replicate a "slayer shot", which I define to mean a fixed flow rate during pre-infusion. I think the machine could do it, but I think I'm flying blind since I only have feedback about the pressure, not the flow rate.

In practical terms, though, if you think of a "slayer shot" more broadly as a shot with a long pre-infusion, and possibly with backing off the flow later in the shot, then it can certainly do that.

eltakeiteasy wrote:Try the water knob mod and leave it open. That is why your numbers are so far off from Peter I believe. Peter correct me if I am wrong.

My numbers were with the water/exhaust knob fully closed. Again, I hold out the possibility that my brass commercial OPV might be contributing an orifice effect compared with a completely stock BDB... But that would be a total guess.

-Peter