Jake_G wrote:I agree. Additionally, while a knob offers a wide range of adjustment, the tactile feedback of a paddle like that on Bianca has some distinct advantages. The paddle provides a better interface for muscle memory (hard to use a knob in the dark) and also makes smaller adjustments easier by virtue of increased arc length for a given angular adjustment. This is geek speak for saying it's easier to nudge a 2" long paddle a quarter inch to the left than it is to accurately twist a knob 1.75 degrees clockwise.

I'll defer to active Bianca users here, but not before I give my soapbox speech on why I think folks are willing to drop 8 grand on a Slayer...

•Line pressure limits maximum pressure but does not control flow.
•Gear pumps control flow but do not control pressure.
•A needle valve does not control pressure or flow rate directly. What it does do is something even better...

A needle valve controls the relationship between pressure and flow. The only way we have to quantify a given needle valve position is by measuring the water debit, which Graham has been kind enough to share with us. What controlling water debit does for us is control how quickly the brew pressure reaches the available pump pressure, or the maximum pressure the puck can generate; whichever is lower. Lower water debit will have a longer ramp, and will eventually reach a point where a given puck won't generate the full back pressure of the pump. Valve openings above this point will hit full pump pressure, and going lower will generate less and less pressure and softer and softer pressure ramps.

So, you can preinfuse all day long at 2 bar, but this is not even close to what Bianca allows you to do with the needle valve. As long as you get the grind right, you can have a steady and progressive preinfusion with a needle valve that allows and in some cases requires a grind that is obsurdly fine and brings out flavors that line pressure alone cannot match. No doubt that this approach may not be best for all roasts (some darker roasts just don't taste good like this), but I assure you that this is very different from your grandma's line pressure preinfusion. Using a needle valve allows pre-brew, which is unique in that it ends by itself, when the puck is sufficiently saturated to generate the full available back pressure that the pump provides (assuming the grind is fine enough to get you there). The puck (in concert with the needle valve, of course) defines this process and as such you are able to gently bring the puck up to brew pressure without manipulating the needle valve at all, if you so desire. Just set a pre brew flow rate and let the puck do the rest.

I think that is why folks buy Slayers. There's a genuine "magic" to what they can do, but Bianca offers even more, at the expense of losing the saturated brew group.

The "even more" is what some of this conversation is referring to in terms of profiling the pressure at the tail end and also the blooming technique that's been mentioned. You can take the pressure as high as you like during preinfusion (Jim S. and Ken F. Found that it takes around 3 bar to fully permeate a tamped puck...) and then cut the pressure (pretty easy) to bloom or hold it at any pressure you like (a little tougher, but plenty doable) to achieve a myriad or differing flavor profiles.

I bring all this up to make sure folks know that this needle valve idea is rock solid in terms of what you can do. Please don't overlook how powerful this tool can be on the front end of the shot when coupled with a brew gauge reading puck pressure. For folks with HX machines, I would suggest getting a tee fitting that you can insert Eric's group thermometer straight through into the group with a side port for a pressure gauge so you can watch the temp gauge for your flush and the pressure gauge for your preinfusion. No doubt you can monitor the flow to control things on the tail end and let the pressure fall where it may to give you what your after, but that pressure gauge in the group is key to really unlock the potential of the needle valve...

Super stoked to you taking this on, Jim!

- Jake

Also Graham, I tried to take a look at your plot in Jake's S20 project thread, and on the Bianca User Experience thread, but it cuts off the entire set of abscissa labels, which makes it unusable, at least for me.

Strange.
I see the complete chart on my phone, but half is missing on my PC

I can see it now.

speedplay wrote:I would say keep it just within one turn. It might get confusing having two full turns and hard to know exactly where you are within that range ( unless there is a pressure gauge/manometer that could be use to correlate to the paddle position within that two full turn range).
I would say a range from about 11 to 1 if looking at a clock face.

As far as pre-infusion, etc., on my machine I can do line-level pre-infusion and control the pressure with an in-line regulator. The pump doesn't come on and currently have the pre-infusion level set to 2 bar. Doing line level you don't have to mess with boiler pressure and the effect it would have on the brew temp.

AS far as this mod is concerned I am more interested in being able to regulate the flow towards the end of a shot than in controlling the pre-infusion rate since I can already do this now.

Flitzgordon wrote:You can google for
Isomac e61 pump manometer gauge 5530011 DN40

It's available from the following link
https://www.ferrari-espresso.com/produc ... 0011-dn40/

You need to use a sealant with it. My Loxeal sealant doesn't have the holding power and it comes off easily.
I'm not sure if it's really a good idea and the gauge will last with coffee getting in it.

Bill33525 wrote:Best price at this store: https://www.lamacchinadelcaffe.com/manometri-lelit.html
Wonder about shipping to US?

Jake_G wrote:I agree. Additionally, while a knob offers a wide range of adjustment, the tactile feedback of a paddle like that on Bianca has some distinct advantages. The paddle provides a better interface for muscle memory (hard to use a knob in the dark) and also makes smaller adjustments easier by virtue of increased arc length for a given angular adjustment. This is geek speak for saying it's easier to nudge a 2" long paddle a quarter inch to the left than it is to accurately twist a knob 1.75 degrees clockwise.

A needle valve controls the relationship between pressure and flow. The only way we have to quantify a given needle valve position is by measuring the water debit, which Graham has been kind enough to share with us.

What controlling water debit does for us is control how quickly the brew pressure reaches the available pump pressure, or the maximum pressure the puck can generate; whichever is lower. Lower water debit will have a longer ramp, and will eventually reach a point where a given puck won't generate the full back pressure of the pump. Valve openings above this point will hit full pump pressure, and going lower will generate less and less pressure and softer and softer pressure ramps.

So, you can preinfuse all day long at 2 bar, but this is not even close to what Bianca allows you to do with the needle valve. As long as you get the grind right, you can have a steady and progressive preinfusion with a needle valve that allows and in some cases requires a grind that is obsurdly fine and brings out flavors that line pressure alone cannot match.

... Using a needle valve allows pre-brew, which is unique in that it ends by itself, when the puck is sufficiently saturated to generate the full available back pressure that the pump provides (assuming the grind is fine enough to get you there). The puck (in concert with the needle valve, of course) defines this process and as such you are able to gently bring the puck up to brew pressure without manipulating the needle valve at all, if you so desire. Just set a pre brew flow rate and let the puck do the rest.

I bring all this up to make sure folks know that this needle valve idea is rock solid in terms of what you can do. Please don't overlook how powerful this tool can be on the front end of the shot when coupled with a brew gauge reading puck pressure. For folks with HX machines, I would suggest getting a tee fitting that you can insert Eric's group thermometer straight through into the group with a side port for a pressure gauge so you can watch the temp gauge for your flush and the pressure gauge for your preinfusion. No doubt you can monitor the flow to control things on the tail end and let the pressure fall where it may to give you what your after, but that pressure gauge in the group is key to really unlock the potential of the needle valve...

JayBeck wrote:Or just buy a DE1 and call it a day!

Graham J wrote:Here you go - hopefully you have the abscissa and related data!