[Edit - title should read "preinfusion" not "pressure profiling"... don't mind me...]
So, maybe I'm not the first idiot to think of this.
Here's the drum:
You have a pump-driven machine with manual (as opposed to volumetric or timed) control.
To implement basic preinfusion, you cycle the pump on/off briefly one or more times before turning full on for the duration of the shot.
Bonus points: on a machine with E61 group, you push the lever to the middle position (pump disengaged but solenoid/exhaust valve closed) before the end of the shot, to give declining pressure toward the end of the shot.
I've experimented with something like: on (2 seconds), off (4), on (2), off (2), on(*) [leave for duration of shot].
And at the other end; once output hits about 30 g and 25 seconds (from (*), so not including preinfusion), turn off pump then engage solenoid once output hits about 40 g in 30-35 seconds not including preinfusion.
So, a few questions...
0. Has anyone else tried this?
1. Is it likely to cause premature wear or damage to the machine?
2. Is it a dumb idea for some other reason?
3. If yes to 2, why? [emoji6]
4. Should I just buy a lever group machine?
5. If no to 4, should I just buy a Slayer?
So, maybe I'm not the first idiot to think of this.
Here's the drum:
You have a pump-driven machine with manual (as opposed to volumetric or timed) control.
To implement basic preinfusion, you cycle the pump on/off briefly one or more times before turning full on for the duration of the shot.
Bonus points: on a machine with E61 group, you push the lever to the middle position (pump disengaged but solenoid/exhaust valve closed) before the end of the shot, to give declining pressure toward the end of the shot.
I've experimented with something like: on (2 seconds), off (4), on (2), off (2), on(*) [leave for duration of shot].
And at the other end; once output hits about 30 g and 25 seconds (from (*), so not including preinfusion), turn off pump then engage solenoid once output hits about 40 g in 30-35 seconds not including preinfusion.
So, a few questions...
0. Has anyone else tried this?
1. Is it likely to cause premature wear or damage to the machine?
2. Is it a dumb idea for some other reason?
3. If yes to 2, why? [emoji6]
4. Should I just buy a lever group machine?
5. If no to 4, should I just buy a Slayer?

my "off" is about 10 seconds :P but have toyed with the concept over the past year, never done it deliberately. Maybe next batch of fussy beans I'll give it a go.
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