Breville Dual Boiler "Slayer shots"? - Page 77

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

#761: Post by Mikk »

Great thread, with lots of helpful info. Being able to have genuine flow control is a terrific thing, though maybe not used to it's fullest on the BDB due to the touchy needle valve control. I think the valve itself is fine, but the small diameter knob isn't suitable for fine control. A long lever attached to the knob gives outstanding control, and though my version could use some aesthetic improvements it works really well. The weight of the lever is balanced to keep the valve closed, and can be opened and controlled with one finger quite easily.

Whilst Slayer machines are renowned for their style of extraction, I've been learning an awful lot from the many published Decent flow/pressure profiles available, and more recently from the Dalla Corte Mina/Zero flow profiling machines.

The Dalla Corte machines offer 4 or 5 fixed g/s steps that can be app programmed in (Mina) or freestyled (Mina/Zero), and is something that can be replicated on the BDB. Not saying that Dalla Corte style is better than Slayer style, but I think an entirely flow-controlled shot (Dalla Corte) vs flow-controlled pre-infusion/pressure controlled extraction (Slayer) has significant advantages.

As an aside, I just also wanted to report the the rubber plunger tip from a 5ml plastic syringe fits perfectly to block the hot water tap outlet, for those carrying out the BDB Slayer mod.


#762: Post by smite »

looks great!


#763: Post by zazuyuzu »

Thanks everyone for all this information. I've just replaced my modded infuser with a DB and am excited about all the possibilities!

Is the slayer mod solely to avoid having to introduce more parts? Is there anything that should stop me from adding a new needle valve inline between the solenoid and the boiler? Or moving the hot water valve to a ball valve and using it for the flow control?

Is there something that I'm missing from this? Or is it mainly to avoid having to drill holes in the sides?


#764: Post by maximatica replying to zazuyuzu »

I have been following the Slayer discussion for quite a while and will probably do the mod sometime soon.

I had thought about a longer handle for the knob to give the same performance (much more probably) to the control of the water.

A posted a photo of a DIY longer handle is above. It is exactly what I have in mind as my left side is not visible due to the position of the BDB on the counter (at about a 45 degree angle).

Anyway, I think that is the better way to go vs. changing out the needle valve. I have attached a graphic I use to illustrate the way motorcycle suspensions work as it is the same principle (only backwards). A large change with the handle will cause a very small change at the needle valve.


So, the swingarm pivot is the needle valve and the thick black line to the right would be the lever. I have to revamp a couple of my 3D printers anyway, and will give making a model some thought.


#765: Post by Jessipoo »

I just did the slayer mod tonight!
What I'd like to understand is what the purpose of plugging the hot water spigot is for?
I had some water drip earlier (and I never used the hot water machine except for once or twice early on, so I'm not sure if that was just water that needed to be flushed out).
I got scared and reopened it up to see if water was spilling anywhere and nope, everything looks dry and fine


#766: Post by Quester replying to Jessipoo »

You plugged the hot water spigot because you moved the hot water supply line from the valve inlet directly to the spigot. As opposed to capping it. This makes the mod easy and also easily reversible.

You shouldn't have any drips from the spigot. If so, redo the seal. I cut a circle out of a collapsable silicone drinking cup I got on amazon. It sealed on the first try and has stayed sealed since I did the mod in 2019.


#767: Post by Jessipoo replying to Quester »

I followed the tutorial to re-route the 3 tubes.
I still don't quite understand why there is water dripping and why we're capping it?

If we re-routed, why would we need to cap? I'm trying to understand this combination
Is it creating negative pressure so you want a perfect seal and then water shouldn't drip out of there?


#768: Post by Quester replying to Jessipoo »

The hot water supply tube you rerouted used to go into the inlet side of the valve that supplied hot water to the spigot. So, when the valve was off, no hot water to the spigot. Now the supply line is routed directly to the spigot. So, it's always on--so to speak. The small disc you made blocks the water and effectively "turns it off."

If it's leaking, it's not entirely sealed. Cut another disc and try again.


#769: Post by Jessipoo replying to Quester »

and if it's not entirely sealed, then I'm losing some water flow?


#770: Post by Jessipoo »

I'm making a video to explain some of the mechanics of this mod and would love to clarify and make sure I understand correctly!

The solenoid, the black box at the back, has quite a few tubes running in and out of it. Some of which we modify.
If I understand correctly
  • the solenoid is like a control box conductor opening closing some of the water in/out supply to direct the water
  • the big tube on the top is the excess water that will be drained to the drip tray when you're done extracting (release pressure)
  • the original tubing, has a tube going from the brew boiler into the solenoid to feed the water supply before redirecting it - we will be playing with this during the slayer mod
  • there is also a tube going from the solenoid out into the T needle valve to feed the water into there from the brew boiler (also playing with this in the mod)
  • there is a tube we will not touch that goes from the solenoid to the grouphead to make espresso - pointing red arrow and highlighted tube on image
is this right? did I understand this properly?