My long and rambling path to preinfusion/pressure profiling - Page 45

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Postby AssafL » Jan 27, 2019, 11:42 am

So is the long and rambling path to PI complete?

May I suggest a similar one for roasting (hint hint)?
Scraping away (slowly) at the tyranny of biases and dogma.


Postby ShelbiRyan » Jan 27, 2019, 12:41 pm

For what it's worth, I get almost the exact same results on my R Nine One when using a long slow pre infusion. At 1.5bar preinfusion pressure, my flow meter climbs to 28ml and the bottom of my puck will slowly start to drip. This is using a VST basket as well.

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Postby Jake_G » Jan 27, 2019, 3:08 pm

Thanks Ryan and Myso for sharing your experiences. I think the important takeaway here is that there is a number that we can use with some predictability to control our shots the way we want to. This ain't the wild west any longer :wink:

AssafL wrote:So is the long and rambling path to PI complete?

May I suggest a similar one for roasting (hint hint)?


I need to finish the S20 and tidy up a bit more conversation in this thread regarding pressure and temperature response at the puck and then the next book can be started. I've been reading everything I can on the roasting forum, so much of the early content of the first few chapters is already taking shape. But I'm not ready yet :wink: .


- Jake


Postby chris_n » Mar 11, 2019, 9:30 pm

is the "bloom pause" possible on a machine with 3-way valve?

I would like to try this on a slayer, but cutting the pump during pre-brew will also open the 3-way valve. Will that cause too much turbulence on the puck?

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Postby Jake_G » replying to chris_n » Mar 11, 2019, 11:33 pm

Hey Chris,

It likely will cause too much turbulence if you open the 3 way valve during pre-brew. The way around this on an archaic machine like mine is to kill the power to the pump by interrupting the signal to the pump solenoid (that's what I do). On a sophisticated machine like yours with a gear pump, you'll need to find a creative way to kill the pump with the solenoid open. Since you're likely plumbed, as well, things get even more tricky because even with the pump off, you still have line pressure hitting the puck any time the 3 way is open.

If Slayer uses a 3rd party pump controller, you could arguably interrupt the enable signal to the controller and kill the pump, but you'd still have the issue of line pressure pushing through the gear pump and 3 way. I'm not sure that this is actually possible without throwing a fault (Lukas, paging Lukas!), but it would be step 1.

If -and only if- you found a way to shut off the pump, you would then need to find a way to close off the line pressure from reaching the puck. This could be done by outboarding the needle valve (and replacing it with a less-precise unit that allows ergonomic adjustment from some relative max pre-brew flow to sealed) and closing it (again, only after shutting off the pump!) Or by installing a solenoid valve somewhere in the brew path that could only be closed when the pump was off...

Perhaps the easiest way to pull this off on a Slayer would be the opposite approach... rather than try to shut off the pump mid-shot, you could find a way to hold the 3-way open with the brew paddle in the off position:

•Imagine a DPDT relay with a switch on it that is powered off of the normally closed contacts on the paddle micro switch (paddle off equals power flowing to the switch.

•The first set of contacts in the relay has power on the common terminal and the normally open terminal connects to a normally open 2 way valve. When power is applied to this valve, it closes off the path from the inlet to the group.

•The second set of contacts in the relay has the solenoid hooked to the common terminal, the factory power wire hooked to the normally closed terminal and power applied to the normally open terminal.

•With the paddle off, power flows through the normally closed contacts of the micro switch to your new "soak" switch. When this switch is off, nothing happens. When this switch is on, power flows to the coil of the DPDT relay and sends power to the normally open solenoid valve, which closes it; power also flows to the 3 way solenoid and opens it.

Here's your blooming shot sequence:

1: Start your shot like normal in pre-brew and turn on your soak switch shortly thereafter; it won't do anything till step 2.
2: Sometime before drips form on your basket, bring the paddle back to the off position. This will simultaneously shut off the pump, shut off the water supply and hold the 3 way open for a bloom phase.
3: Once your bloom is "complete", bring the paddle back to pre-brew to build brew pressure.
4: Finally, bring the paddle to the brew position to pull the shot in earnest.

It sounds like a mess but really, it's only two new components and they can be installed outside of the machine and the mod would be 100% reversible. Since the machine is "in between shots" during the bloom phase, I dont think you'll be in any danger of unwanted fault codes or anything like that...


- Jake


Postby pcrussell50 » Mar 11, 2019, 11:38 pm

chris_n wrote:is the "bloom pause" possible on a machine with 3-way valve?

Yes. I have done it on my needle valved machine. Your pump will have a power wire attached to it. You insert a switch into that wire to independently cut power to the pump. So you would start your extraction as usual with the first detent of your paddle. At that point the solenoid is energized and the pump comes on (using the pre brew path). To pause the pump and bloom, you throw the new switch you wired in, to interrupt power to the pump and the pump shuts off while the solenoid remains energized. You will hear the solenoid humming in the quiet with the pump not running. When you are done blooming, close the switch and the pump resumes.

chris_n wrote:I would like to try this on a slayer, but cutting the pump during pre-brew will also open the 3-way valve. Will that cause too much turbulence on the puck?

This was the same on my machine. That's why you use a separate switch, so you can cut power only to the pump.

LMWDP #553

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Postby AssafL » Mar 12, 2019, 3:49 am

I recently did something similar on the GS3 with my profiling mods.

I also had the 3 bar mains issue and the needle valve bypass style the slayer. For a time I manipulated the needle valve and grew tired of it.

So I did the following:
1. Close the needle valve so that under the 3 bar mains it is nearly shut altogether. In fact the manaometer registers between 1-2 bar at the end of bloom.
2. Raise the pump speed during PI initial fill. That forces a nice flow during PI. (For the Chimera I made opening and closing the associated solenoid reversible. So that I can brickwall PI at maximum flow, - stall it - and pull. )
3. Cut the enable line on the pump to stall it. (For the Chimera the controller cuts to zero).
4. When puck is saturated - proceed to full pressure full flow.
Scraping away (slowly) at the tyranny of biases and dogma.