The Super Strega: Modifying preinfusion pressures and other functional improvements - Page 4

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TomC (original poster)
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#31: Post by TomC (original poster) »

So this is some of the last random tweaks I put into the Strega. Cumulatively it was worth it, but I spent a good hour playing around with various things learning as I went. My main goal at this point was to try to reduce the noise level from the vibe pump. Many times, the vibe pump will literally vibrate itself into an orientation that ends up having close by wires lay against it, which make the noise even worse, or just the odd angle made it rattle more. After observing it cycling on and off several times and checking for where things happened to lay close to the pump, I started re-routing things slightly, using small zip ties and isolating everything away from the pump as best I could.



By routing these zip tied blue and black wires onto the other side of this pipe, there's less slack to lay down on top of the pump on the other side.




I used things I already had laying around, except the zip ties which cost about $2 I bought a bunch of random neoprene washers back when I got the wood handles for my HG-One, so I used a few as spacers between the metal to metal contact of the feet and the case. I have no idea if these helped much, but I already had them and they took only seconds to install. I also put one under each of the two counter weights.



Between the feet and the case. They can't be seen from the top.


This stock copper feed line lays close to the vibe pump. There's about an 1/8th of an inch gap between it and the pump and mounts. I wrapped it with electrical tape.



Ignore the water drops. Everything was cleaned and dried up before retesting.


Then after a moment of inspiration, I went out to the garage and grabbed a roll of sound deadening aluminum tape (they call this stuff Dynamat, but it's about 1/20th the price when the same thing is picked up at Home Depot under another name, its just an asphalt/rubber adhesive with a very thick aluminum foil tape used for roofing, gutters, etc, where waterproofing is needed. I picked up about 5 rolls of it ( about $7 a piece) at Home Depot back when I insulated the trunk of my muscle car after adding an aftermarket exhaust. I had a left over roll and was pretty certain it would do the job of bringing down the noise level of the Strega significantly, but I had to take the chance that I'd have a messy, long laborious task of removing it all and cleaning it off it ended up smelling up my kitchen like a freshly paved road. Turns out, it didn't, you can't even notice its there except for the added heft of the case and the greatly reduced noise level.

I carefully measured out each strip, laying them in then covering the seams that were left with the plain aluminum tape I had for the drum insulation of the Quest M3. Popped it all back together and tested it out. Much, much quieter and I checked back every hour or so to see if there was any odor (no). Since I had so much, and no other plans to use it for anything else, I put a double layer down towards the bottom which is right next to where the vibe pump is located and where it would do the most good.





I didn't bother taking a final picture, but you get the idea. All sides were eventually coated.


Afterwards, I thought about downloading a free mobile app that does simple decibel measurements. I should have done this beforehand to see what it was like when stock, but using Sound Meter PRO from Mobile Essentials (free on the Play Store). Certainly non-scientific and subjective, but maybe someone with a stock Strega and the same app can test it out and see what they get in a quiet environment. I set it on the counter right next to the machine. This is the measured sound output with the pump set at it's highest, loudest setting. Anything less than half power and I can't hardly even hear it. So an hours worth of work was worth it for me.

This would likely work even better for a vibe pump driven machine that relied on a vibe for more than just brief pre-infusion. But I didn't like the racket it made, no matter how short lived.


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TomC (original poster)
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#32: Post by TomC (original poster) »

I always wanted an easier way to adjust my pressurestat without having to disassemble the entire top lid to get to it. Using a 11/16th's hole cutter and lots of cutting oil (stainless isn't fun to cut) I knocked out a hole one and a half centimeter in from the right side and seven centimeters back from the front edge. I made the hole much larger than the diameter I'd need to get a screwdriver down in and adjust it. I know I don't make adjustments frequently on my pressurestat, but now I have one less barrier if I choose to, I'll likely tweak things a lot more often and easier.

I used an adhesive label over the area I knew I'd want to drill, measured about 3 times before making a crosshairs marking, a center punch to help center the bit, and plenty of cutting oil. Then some 600grit wet/dry sandpaper to smooth the edge out.



I can see easily now, straight down to the Sirai Pressurestat. Unfortunately, some earlier Strega's like John's and likely a few others had Mater's or something else, so I don't think this would work as well for them.


It's nice now to have the Strega fully back together and running well. I had it off for the most part for the last few weeks since I was getting a nose drip from the steam wand, now fixed with some new gaskets. I'm still thrilled how quiet everything is.

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Olav

#33: Post by Olav »

I just want to say "WOW!".

I'll be digging into my Strega when I get it and consider some of these awesome suggestions.

Thanks!

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TomC (original poster)
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#34: Post by TomC (original poster) »

Last thread bump for now, but the one thing I discovered that I should add and is relevant and very useful to all of modified Strega users is if you do the insulation of the outer case, not only does it quiet the whole thing down so well, it also adds just enough more weight to prevent the unit from ever tipping forward.

It's a nice feeling, since on occasion, I've noticed that pulling the lever used to make it want to tip forward off it's rear feet once in a while. I had considered putting a bag full of pennies or coming up with some other kind of metal weights in a bag or container that I can set in the back, but now, I don't have to.

After about a weeks worth of use, everything seems to be settling in nicely and it's gotta be as quiet as my Duetto 2 was. It just makes much, much better shots :wink:

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JohnB.
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#35: Post by JohnB. »

TomC wrote:It's a nice feeling, since on occasion, I've noticed that pulling the lever used to make it want to tip forward off it's rear feet once in a while.
I guess this is one benefit of running the machine off of the internal reservoir as I haven't had that issue. The combination of the water & the counterweights keeps my Strega firmly planted when I pull the lever down.
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TomC (original poster)
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#36: Post by TomC (original poster) »

Today I was putting together a few thoughts about what Steven Sweeney and others found with pucks hopping up in the basket, on lever machines, due to the vacuum briefly created above the puck as air is drawn up thru (or potentially around) the bottom of the basket, thru the coffee bed itself and filling the chamber above the puck. The puck is seen in the video briefly hopping up, and then falling back down before the extraction begins. The question as to whether this can decrease the extraction, or increase the risk of channeling would take a tremendous amount of work that I'm not prepared to hash thru.

But I realized with my pump modified the way it was, I could completely prevent such a phenomena from the start. It's actually an easier step than my normal routine. I lower my pump to it's lowest setting (right after preparing the basket). I then flush the group into my cup to warm up the cup a bit ( I prefer this to super hot cups for all my drinks). With the pump lowered to its lowest setting, once the volume of water in the group has dropped into the cup, there's significant moments of time between drips of water in where you can engage your portafilter, and simply start your ramp of pre-infusion as you desire, before you lift and disengage the pump and let the spring take over.

I'd coordinate efforts to flush the group into the cup and warm it, dump the water and lock the portafilter, and it was all a streamline effort.

I've looked at many of my spent pucks and have on many occasion seen a very thin separation of the puck from the wall of the basket. I won't make any claims about this technique, but I think since it doesn't require any extra work on my part, I might as well continue on using it, because looking at my pucks since, they look like this, as opposed to an occasional wall gap. Whether that wall gap is because of something other than this potential "puck hoping" (it could have other causes, just as easily) it's going to something I pay attention to going forward, because it also seems to limit "donut extractions".



If lever espresso machines do in fact lift the puck on occasion during the beginning of the extraction process, and if that creates an opportunity for channeling, whether it's due to poor prep or not, it might as well be avoided.

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drgary
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#37: Post by drgary »

This thread is really something. It makes the Strega even more versatile. I appreciate the fine photo documentation and will probably use these instructions as a guide to reinstall a vacuum breaker on my commercial lever. I got to a similar point of wanting good access to PSTAT settings and decided to go with a PID.* This made it very easy to adjust temperature on the fly to exactly where I want it, especially when sampling different roast levels in the same session. Since I don't own a Strega does that mod make sense or does it already have fine temperature control elsewhere that I'm missing?



* I'm not a PID enthusiast on some of the small home levers but like it on a larger machine like this.
Gary
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Beenbag

#38: Post by Beenbag »

drgary wrote: I got to a similar point of wanting good access to PSTAT settings and decided to go with a PID.* This made it very easy to adjust temperature on the fly to exactly where I want it, especially when sampling different roast levels in the same session. Since I don't own a Strega does that mod make sense or does it already have fine temperature control elsewhere that I'm missing?.
The Strega has thermostat controlled electrical heater cartridges in the lever group, so it may be more effective to convert those to PID control ( for easy temp adjustment and display) , rather than the boiler.
That should be a easy mod if a suitable location for the PID temp sensor can be found . ( and a neat location for the display )

PS.. has any one detailed the mod for connecting in a pressure gauge for brew pressure ?
Im guessing it would have to be tapped directly into the group cylinder somewhere ( close to the PF ?) in order to accurately read extraction pressure throughout the lever stroke.

okmed

#39: Post by okmed »


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JohnB.
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#40: Post by JohnB. » replying to okmed »

Since that tee fitting is before the OPV I have to wonder if tapping in there will give you accurate Pre infusion pressure readings. I broke into the line between the HX & group & added a Tee fitting when I installed my P/I gauge.

If you wanted to read actual pressure readings once the spring is engaged you would have to tap directly into the group. Center drilling the piston & running a feed out through the top of the group would be one option. Tapping into the lower bell would be another.
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