Home-Barista.com

Unbelievably huge, unqualified success!

We now have not just "Slayerlike" shots, but actual Slayer shots. And it's easy. And it's reversible (your merely re route some of the tubes), and it's free, or nearly so.

In a nutshell, I routed the brew line through the hot water valve, which is a needle valve. This means ALL of your brew comes through the water valve. If it is closed, NO water gets to the puck/group, no matter how hard or long you run the pump. To do a Slayer shot, you just crack open the water valve, start the pump right at full pressure and keep it running. After it fills the headspace above the puck, pressure will start to build, only just as with Slayer, it will build all the way and not stop at one or two bar, even though the actual flow is still slow. You will see the thickest stickiest gloopy gloppy espresso start coming out and then you can increase the flow by opening the knob (at whatever rate feels good to you). As the shot progresses, you can slow the flow by progressively closing the knob as you wish (which you cannot do on Slayer), and end the shot by turning off the pump or closing the valve all the way and then turning off the pump. My very first shot, with no practice and experimentation, was a masterpiece. I just used the same grind setting that I had been using for the last few weeks doing Breville-"Slayerlike" shots using PP55. I wish I had four hands and an LED espresso light and a fancy mirror for video'ing. You guys would die.

If you've got some dark beans and don't want to do a Slayer shot, just leave the water valve full open and it will work just like normal, with your pre infusion settings and all.

You will of course, no longer have use of your hot water knob for tea. For that, I have a 1500watt glass kettle with temperature selection. Well worth it if you drink tea, Aeropress, or pour over. Coincidentally, it is also a Breville. But I am not a shill for Breville. I have that kettle because my wife actually wanted it and picked it out completely independently from me and my input.

Full credit to Jake_G for this idea. It was not mine. Jake does not even have a BDB. But he has a big brain.

Words cannot describe how elated I am over this.

-Peter

WooHoo!

Peter,

In lieu of videos, can you post a few pics of which lines you rerouted and how you capped the extra line off the boiler?

As I noted in a PM, you can now close the water valve and do a "Rao style" soak shot in addition to Slayer preinfusion and full intra-shot pressure profiling with no water waste. It'll only be a little while before others employ this mod and we get some eye-candy videos with lighting and shot mirrors detailing the splendor.

Welcome to the once ellusive club of variable water debit machine ownership. It's a phenomenal capability! FWIW, I usually flush a bit before my shot and set the debit at the tail end of the flush for repeatability, but you can also quicken your shots now by quickly filling headspace and then slowly ramping pressure. You basically have anything Bianca can do at your fingertips now, so be prepared for sensory overload!

Cheers!

- Jake

Jake_G wrote:Peter,

In lieu of videos, can you post a few pics of which lines you rerouted and how you capped the extra line off the boiler?

- Jake

Two videos on page 18. One showing low water debit with pump running at full power (like Slayer), the next showing a shot, and how you eventually reach full pressure during low water debit.

Plumbing:

1) Took the main brew line, where it enters the solenoid, and moved it to the INput of the needle valve. (Same ends and o-rings so no cutting or modding)
2) Took the OUTput line on the needle valve, disconnected it from the it's endpoint on the spigot, and ran it to the newly vacated (from step 1) entrance to the solenoid. (Same ends and o-rings so no cutting or modding)
3) The water line that used to terminate on the INput of the needle valve, that was detached in step 1: It gets capped off and not used. But you must cap it or all your pressure will go through it. You can cap it any way you like. What I did was, run it to the now vacated, water spigot and attach it there. I snaked it underneath the group, towards the front of the machine, and up the gap between the brew and steam boilers and attach it to the water spigot, vacated in step 2. You will need to plug the water holes in the tip of the spigot. Unscrew the water spigot tip and replace it with a metric threaded cap. Or: cut a disc out of an old bicycle inner tube or a sheet of silicone (cheap on eBayZon) and put it inside the cap to block the holes and screw it back on.

Test for leaks before putting the cover back on.

Enjoy.

-Peter

One figure I do not know whether is normal or not is the flow with the valve wide open. I did just on test pull and got 186 ml in 30s. Seems not disastrously slow, but I've heard of faster. Bob, (and others), what are you getting on your stock BDB at full pump power?
If you have some means of capping off the water line that goes TO the water needle valve, like a spare or even an old steam ball valve, you can do the whole kit and kaboodle in 10 minutes, working carefully, once you open the top cover. As an alternative to capping the water feed line, you _might_ be able route it straight to the now vacant water faucet. Then uncrew the tip and put in a plug where the tip was, using the same thread as the tip.

-Peter

pcrussell50 wrote:One figure I do not know whether is normal or not is the flow with the valve wide open. I did just on test pull and got 186 ml in 30s. Seems not disastrously slow, but I've heard of faster. Bob, (and others), what are you getting on your stock BDB at full pump power?

Yeah, 6ml/sec is not terribly fast, but is in line with what Graham has found on his Bianca here. Given the limited swing of your hot water valve, I think this is pretty good and implies better micrometric adjustment of the flow than what I would have thought, given the earlier comments. This could be an artifact of having the needle valve in series with the 1mm flow restrictor in the manifold block. I'm not sure how much of a chore it would be to remove it, but if you wanted higher water debit at wide open, it would be a reversible approach.

Alternatively, is there a way to reversibly increase the throw of the hot water valve handle? If you could get another 90° of rotation out of it, you might be able to increase the flow if you so desired. I find that my flushes are better at cleaning the screen around 8ml/s and if there's anything stubborn on there, I kick it up to 12 or higher to blast it clean. 8ml/s perfectly mimics the 0.5mm gicleur that my needle valve replaced, so I suspect that the BDB has an even higher flow with the 1mm restrictor in place, but tank-fed vibe pumps aren't quite the same as plumbed rotary pumps when it comes to volume on demand...

Cheers!

- Jake

A little more:
In addition to the wide open valve flow being about 186ml/30s or about 6g/s, which is not super fast for the big dog rotaries. 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.

Also, while it's easy to adjust for flow, the knob only moves about 90 degrees from full closed to full open. If it took more degrees of arc to go through the range, you would have finer control, but yet I'm not sure how badly it's needed. You have full control as is, and you don't have to have the fine motor skills of Neil Armstrong landing an out of position lunar module, to make shots exactly as you like. In the end, it might be geeky hair splitting to aspire for more. But I am a geek. So we'll see. I'll try to get a vid of the pressure gauge tomorrow. Exhausted from TWO long hard cricket games today and going to bed.

-Peter