Breville Dual Boiler "Slayer shots"? - Page 34

Need help with equipment usage or want to share your latest discovery?

Postby pcrussell50 » Mar 16, 2019, 6:42 pm

Your pump noise sounds fine to me. The sound will vary. It's ok.

Also, I do mine "Slayer style". I don't bother with the programmable pre infusion. I just run the pump at full power the whole time and control the flow with the needle. Slayer has only one pump speed, high, as well. Some others do use the programmable pre infusion part of the time, like you are.

Finally, re sensitivity, response will never be linear. Pressure, as distinct from flow, will always start slowly and accelerate for a given needle position. And as the puck erodes, flow will increase for a given pressure. Life in flow profiling.


LMWDP #553


Postby BaristaBob » Mar 16, 2019, 9:29 pm

rosslyn568 wrote:Also, out of curiosity, what do you have your OPV set to?

Hi Chris,

Not sure I saw this question answered for you...mine, and many others are set to 9 bars. That's sort of "industry" standard, however, I know a few people that like their OPV set to 10 bars, while others like 7 to 8 bars.
Bob "hello darkness my old friend..."


Postby mrjag » Mar 16, 2019, 9:46 pm

10.5 bars with a blind insert results in 9 bars at the puck for me.

User avatar
Moka 1 Cup

Postby Moka 1 Cup » Mar 16, 2019, 10:01 pm

I did not touch mine. After preinfusiom it is almost always dead on at 9 bars. Sometimes it fluctuates a little between 8.5 and 10.
“By tradition cappuccino is made of 25ml espresso and 100ml steam-foamed milk”


Postby Quester » Mar 18, 2019, 4:19 pm

Just finished the mod on my BDB. First shot pulled was an Ethiopia Bensa Shantawene. I was just guessing at the pressure profile and ended up with a sweeter shot than the traditional 9 bar shot I was pulling this morning. Maybe I got lucky. But it's pretty exciting.

I had no trouble routing the line to the water nozzle—the coat hanger worked first try. All the plumbing took under five minutes.

The only issue I had was sealing the water nozzle. I cut a circle out from a food grade collapsable water cup, but it leaked the first time. I simply added more circles and pushed them down to create a slight bit of pressure. It sealed after I did this.

What a great idea you guys! Now I'm noodling how to mod my GS3 . . . .

User avatar

Postby johnny4lsu » Mar 18, 2019, 4:40 pm

Welcome to the world of profiling.


Postby pcrussell50 » Mar 18, 2019, 5:28 pm

Quester wrote:What a great idea you guys! Now I'm noodling how to mod my GS3 . . . .

Boy, if that isn't the question of the year! Ever since I got my first BDB when they first came out in fall of 2011, I always told myself I'd just see what this dalliance was all about, then I'd cut to the chase and get a GS/3... And, yet... over the years, this little dalliance was able to keep up with all the hottest extraction techniques, while also proving quite reliable to boot... It just has never (yet) given me good reason to leave. It's the darndest thing.

As to flow profiling the GS/3, it seems like your best/easiest route would be to rock it old skool and go the "Slayer" route. By this I mean, instead of having the whole shot under our direct control from start to finish through the needle valve like you do now with your BDB, you would plumb in a second path, one for high/normal flow, and one for low/pre infusion flow. This second path will have a needle valve that you pre set before the shot, but have no direct, on-the-fly control over. If you don't like where it's set, adjust it up or down before your next shot, and repeat until it's to your liking. You start your extraction in low flow, then switch to high for the main part, then back to low, to finish. Having only two discrete flows sounds crude in comparison to what we have now, but I and some others suspect that while it's crude, it still captures a lot of the benefit of full control all the time, even if it's not quite as capable. Look up HB'er Shawndo. I think he did this on his LM Shot Brewer (GS/3 without steam). Otherwise you are looking a Assaf's "Chimera" gear pump with Arduino custom controller or Pepperssas Dick Green's similar. These sound immensely capable, though they are using gear pumps on a custom controller for precise flow control. Might be a considerably bigger job than taking the "Slayer approach".

LMWDP #553

User avatar
Team HB

Postby Jake_G » Mar 18, 2019, 5:51 pm

For a GS/3 AV, I would use the approach we have been using, but install the "whole shot" profiling valve in the line from the HX mixing valve to the brew boiler. The tricky part will be finding a convenient and non-sacrilege way to mount and actuate the valve.

Had I a donor GS/3, I'd figure out a way to get this done and have it look great. If anyone wants to provide me with a GS/3 for prototyping, just PM me :)




Postby pcrussell50 » Mar 18, 2019, 7:00 pm

Very much this ^^^

If you think you can abide a situation where you can plumb a valve outside the machine, with a direct knob right on it, you should be able to do it this way. If you have the MP, you would be using the paddle strictly for on-off.

LMWDP #553

User avatar
Team HB

Postby Jake_G » Mar 19, 2019, 8:31 am

Had I an MP, my solution would be very much different.

Whether equipped with the new conical valve or the old Ryton (or was it PEEK?) valve, the MP design is seductive in its simplistic beauty of eliminating the solenoid brew valve. It would be a waste to have all that range of motion and not use it to profile the shot.

The details would be different between the two solutions, but the end result would be the same in that I would modify the factory valve or fabricate a new one to eliminate the overlap between the pressure and exhaust ports and implement a needle and seat in between the pressure and brew group ports. Such a paddle would have a very short throw from pressure to exhaust and then the rest of the paddle movement would be throttling the flow from zero on the right up to full flow on the left.

It all sounds complicated but there's not really too much going on in the MP valve (either of them), so it's really just a matter of careful port placement to eliminate the overlap and make the transition from exhaust to pressure happen very quickly and then working out a good taper on the needle and seat combo to get you the flow rate range you're after.

It's all very doable with a little time spent ironing out the details. Had I an MP, it would not live if stock form for very long :wink:


- Jake