The Super Strega: Modifying preinfusion pressures and other functional improvements - Page 3

#21: Post by **JohnB.** » February 26th, 2014, 8:04 am

Oskuk wrote:Btw What is the reason for "Vacuum Relief Valve Drain Line Modification"?

It sends the water that sprays/drips out of the vacuum valve to the drip tray instead of letting it spray or drip on to the electrical connections below.

February 26th, 2014, 12:03 pm

For reference to others, I updated the first post with photos and reasons why.

February 26th, 2014, 3:39 pm

JohnB. wrote:The dimmer allows you to fully pressurize the group at any pressure. I was surprised to see that I can set the vibe pump to put out a steady 1 bar. Trying to get low P/I pressures by lifting the lever & cutting the pump after a few seconds won't put much water in the group so your spring will be engaging way up near the top.

That's interesting. I always assumed no air escapes, so if you pressurize a lever group to 1 bar, you fill it 50%, at 2 bar, 2/3rds, at 3 bar 3/4ers, etc etc. I guess the slow fill up with the reduced pump pressure allows some air to escape through the puck.

#24: Post by **JohnB.** » February 26th, 2014, 7:04 pm

It works the same at 1 bar, 2 bar or 10 bar. Let the pump run until it goes silent, the group is filled & the lever engages at the 9:00 position. Whereas it takes 10-12 seconds with the pump running full pop to go silent at 10-11 bar it will take about 18 seconds with the dimmer set to hit 1 bar. The up side is you get a long slow P/I at less then 1 bar until the pressure "ramps up" to 1 bar at the end.

February 26th, 2014, 7:19 pm

Then having the dimmer switch and pump pressure gauge in the same box makes for the easiest operation.

February 27th, 2014, 6:29 am

Two hours of editing and I have it neatly spelled out with a hot side wiring option. I think a 4th grader could accomplish this modification now, just by following the pictures and prompts.

Next step will be the sound insulation, fun stuff.

February 27th, 2014, 6:57 am

Great .
So basically you could manipulate a pull and give it the pressure profile you want just using the mod.Slayer like extractions.

But doesn't this make the lever redundant?
You could simulate a lever pull using just the mod.
Brings to mind what Reiss called the Strega a long time ago.
" A pumpmachine with a lever attached as a piece festive decoration".

February 27th, 2014, 8:07 am

Yes (sort of) I can't influence the initial flow, the water just drops down via gravity, but I can influence the pressure or lack thereof. I said as much in the original thread that led to this "how-to" I'm trying to keep the two separate, this will just be for a few more mods I want to share. But the actual playing around with it and the cool stuff we can do with our extractions belongs there.

February 27th, 2014, 8:12 am

Next step would be some software that simulate certain pressure profiles and a motor to control the switch.

Love this .

February 27th, 2014, 8:57 am

espressotime wrote:Brings to mind what Reiss called the Strega a long time ago.
" A pumpmachine with a lever attached as a piece festive decoration".

All pump shots I've tried on the Strega suck big time. It could be that keeping the lever down and running the pump with declining pressure would pull better shots, but I doubt it. The Strega's HX is different from the Bezzera pump machines, and is probably designed to feed the lever cylinder, not to be "on-line" during the shot. The temperature would not decline, but rise, and cook the shot. In any case, it's not that easy reproduce the spring profile even with the high end profiling machines.

And when it comes to assessments of the Strega, Reiss has not been the most credible of espresso machine design geniuses.