My long and rambling path to preinfusion/pressure profiling - Page 2

Need help with equipment usage or want to share your latest discovery?
User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#11: Post by Jake_G (original poster) »

Chapter 4: The fun starts

I get home on a Friday afternoon sometime in March (it's really January), 2012 (2013) with a behemoth of a machine tucked safely in the rear seat of my 92 Honda Civic. Heidi is not really amused. At all. But she graciously explains that as long as i get it working and it makes great espresso, I can remain her humble man-servant for the foreseeable future. Whew. Better to ask forgiveness, right? One thing we immediately both agreed on was that Krupps was in no way, shape or form going to be able to properly grind our beans with this setup. Silvia had been rudely kicked from her throne before she even showed up. What to do about our plans for Rocky???

This weekend, I drain the boiler (ick!) and STRIP the machine down to a bare frame, being careful to replace all the fasteners loosely back in their respective locations as I remove each sub assembly from the machine. The stainless cup warming tray and aluminum side and back panels come off super easy. The drip tray and pan are well-designed and slide out easily after figuring out how the tray locks into the stainless backsplash that houses the indicator lights, boiler pressure gauge and power switch. From reading the owner's manual over the last few months, I know the industrial power switch has 3 settings. To the left is position "1". This activates the fill logic on the control board without energizing the heating circuit. It turns on the pump and the fill solenoid until the ralls sensor (why is it called a ralls sensor?) senses continuity to ground by virtue of trace amounts of mineral content in the water. The center position is labeled "0" and turns the machine off. To the right is "2". This brings the monster to life, heating element and all. The switch rotates from position to position with a satisfying "clunk" of a component designed to last pretty much forever. I'm getting excited.

After carefully removing the entire wire harness, I get to the point of removing the thermosyphon tubes feeding the groups from the top and bottom of the heat exchangers. They are full of water. Gross. After recovering from that, the groups come out, the solenoids are broken down, the shower screens and jet breakers are removed. I then pull the injectors from the bottom of the heat exchangers and all the pressurized plumbing from the pump to the boiler. There's a lot of stuff here... After the pressurestat, safety valve (which is conveniently plumbed back into the drip tray), steam and hot water valves with associated plumbing, vacuum breaker and steam gauge fittings are removed, it's time to pull the boiler and remove the brass end cap. It was pretty scaly in there, but nothing compared to the aluminum boiler in a 1970-something Gaggia Baby I cleaned up years later.

I put together a parts list and start looking around to see where I can get everything I need. So far I know I need brew group, boiler cap, and heating element gaskets, "lite" rebuild kits for the steam and water valves to be safe, shower screens and jet breakers, a couple Rancilio 14g ridged baskets (Why? Just why?) and a Silvia V3 3-hole steam wand tip to round things off. Right around the time I get the list together, I convince Heidi the we should go look at a grinder in Eugene. She comes along and quickly agrees that $250 for a 2004 Mazzer Super Jolly from a failed coffee shop is, in fact, a good deal. We pass on the 3 group Wega he wants $1500 for and the Fiorenzato decaf grinder, with it. With a commercial grinder in hand, I add a set of Duranium burrs to my parts list and the choice of vendors becomes immediately clear. Not only does our very own Stefano have everything I need, it turns out Espresso Care is no more than 10 miles from my front door. Our schedules never did align for me to actually meet Stefano, but he painstakingly answered so many of my questions and had everything I needed available for pickup within a week or so. I couldn't have been a happier customer and it was super reassuring to be entering this hobby in earnest knowing I had such a stellar resource so close to home. All the above, including the burrs, a 32 oz can of cleaner, a group brush and a rubber backflush disc was just over $150, with free pickup from Stefano's place. (it was really $210. I just found the invoice. The burrs were $64.95, which i spaced when i first wrote this. The invoice was also dated in February of 2013. Shows how good I am at keeping track of time :| )

All told, I'm sitting on a completely disassembled commercial espresso machine (read 5 gallon bucket full of copper and brass parts), a pristine and perfectly functional commercial grinder, and all the parts needed to get this show on the road for right around $600 (ok, it was just over $650, but still :wink: ). I am not sure how I could have ended up in a more favorable position... I bust out the dial indicators and get my beautiful burrs installed first. They do take some finessing to get into the lower burr carrier level, but after about 12 rotations, slowly tightening each screw a little bit, I get them to within a half a thou on the readout. Not perfect by any stretch of the imagination, but pretty darn good. The next couple months were spent smacking myself in the forehead over what I had missing out on over the last few years by using a plastic grinder. Coulda had a V8!

The Mazzer paired with Francis is making a very consistent shot, but straight shots are still not drinkable. The chances of my brew temperature being adjusted properly are about nill. I am preinfusing primarily out of muscle-memory at this point. Pump on for two seconds, pump off for 5, pull the shot. Its part of the routine. Why am I doing this? It's part of the routine. That's the only answer I have today. What is pressure profiling?

The beast awakens in the next chapter and things stagnate pretty quick. The hubris is taking over. Coffee can't get better than this. I have a commercial machine, after all... I'm pretty sure there are never any real problems to speak of on the handle side of the portafilter, right? Man, 4 years in (actually it's been 5) and I have come so far. It will take another 5 before I even realize I'm an idiot (only 4, that's better, right? ). Sad... :(
LMWDP #704

User avatar
lancealot
Posts: 1139
Joined: 7 years ago

#12: Post by lancealot »

A fantastic read. Thank you for sharing. Keep 'em coming.

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#13: Post by Jake_G (original poster) »

Chapter 5: WHAT DID YOU DO??? HALF THE HOUSE HAS NO POWER!!!

It's a pleasant early evening sometime in May, 2012 (based on my invoice and subsequent email conversations with Stefano, I'm thinking this story happened in March, 2013). I'm eating my dinner of mashed potatoes and something else on the back patio with a fresh coat of mustard covering recently received 2nd degree burns on most of the fingers and the palm of my right hand as I patiently wait for the utility crew to finish changing out the transformer that feeds our house. Adding up the events of the day thus far, this was not one of my better days...

Earlier in the day, all was well. After weeks of cleaning every last little component, which included taking the boiler end plate and heating element to my work to be bead blasted and truing up the gasket mating surfaces on the lathe, everything was finally back together. The S20 was drinking out of a 2-Gallon plastic water jug and draining into a 5-gallon bucket, which was tucked behind the doors of the work bench in the garage. I had cut in a welding outlet just below our breaker panel, right above the work bench that worked perfectly for powering up the beast.

All the pre-start-up resistance checks look good, and I plug it in and turn the switch to position "1". The power light comes on, along with the orange low water level light and shortly thereafter the pump kicks on. I wait cautiously as 1 liter of water is sucked from my little water jug. 2 liters, gone. 2.5 liters, a little more and "thunk". Pump turns off, orange light extinguished. Phase one complete. I fill up the water jug and try out position "2". I don't have to wait long before the boiler feels warm to the touch, maybe 2 minutes, max. Shortly thereafter, the thermosyphon tubes begin getting warm (my memory must be blurry here, because at this point in time, both heat exchangers are empty so there's probably not much heat transfer happening and not likely much heat in them there thermosyphon tubes, but let's not let knowledge and/or factual historical events get in the way of a good story...). At 6 minutes, the vacuum breaker valve starts dancing, the E-clip chattering on top of the valve body before it does a series of full spins and satisfyingly lifts into position and seals with a sound that I am certain I cannot spell... Within 20 minutes of powering on, the Sirai pressure stat settles into a pattern: 3 minutes, 23 seconds off, 25 seconds on. The deadband is 0.25 Bar. Not bad so far.

Time to check out the groups. The MIDI CD version of the S20 is a semi-auto machine, which is a bit of a misnomer for this entire class of machines, since the only thing "auto" about semi-auto machines is that they have a button that turns on a pump instead of a lever, but I digress... I hit the brew button on the left group. The pump starts, and hot water flows from the left group (obviously after the pump fills the HX circuit for the first time). Good deal. Today is going to be great. I can feel it.

On to the right group. This time, the pump kicks on, but no flow... Hmmm. I scratch my head. Left group, water. Right group, nothing. The brew buttons are pretty simple on most semi-auto commercial machines with 2 sets of contacts and 4 wires. There are two energized power wires (line) and two switched leg wires (load). One pair for the pump, one pair for the solenoid. Stupid simple. The colors Rancilio used for each switch is one red hot wire, one black hot wire, brown wire to the pump, red wire to the solenoid. Since the pump is working, I figure I must have the red wires crossed on my switch. Power down, unplug for good measure, swap the wires, plug back in, power back on. Ready to rock... Have you ever had one of those moments, right before you do something a wee bit risky, where you quickly ask yourself "Are you sure this is a good idea?" and you shake it off with a quick "I'm sure it will be fine."?

It wasn't fine. It wasn't remotely "fine".

As I press the right brew switch, I see a small spark, hear a large "pop!" and immediately notice that my hand is no longer touching the switch and also that the switch has literally blown apart. I quickly shut the power of and check the breaker in the panel directly above the machine. Whew. Didn't even pop the breaker, I think to myself. I have a few moments to find the bits and pieces of the switch, which miraculously are not damaged beyond a bit of slag on the contact surfaces. The rocker simply popped out of its holder, letting one of the contacts fall to the floor. The other contact is sort of welded to the inside of the switch body, but oddly enough, it breaks free and cleans up nicely. I power the machine back up and everything sort of seems ok, but the green power indicator looks weird.

I have no explanation for how I was able to get the switch back together as well as have a general assessment of the situation together before the following took place. There must have been some sort of time warp involved, because I can guarantee you that it didn't take Heidi more than 3 seconds to notice something was not right...

"Jake!"
"Yeah, hun?"
"WHAT DID YOU DO???"
"Um, nothing. It's fine." (Did she hear that pop from inside?)
"WHAT DID YOU DO???"
"It's fine, I didn't even pop a breaker..."
"HALF THE HOUSE HAS NO POWER!!!"
"Whaaaaaaaaaa???" (She didn't hear the pop...)

I check the breakers again. Nothing tripped. Garage lights? Check. Kitchen? Check. Bedrooms? No dice. Thermostat? Nope. Oven? Negative. I pull the cover of the breaker panel and check voltage at the lugs coming in from the meter, before the breakers. Left side: 120V (should be 120V :) ). Right side: 0V (should be 120V :( ). Left side to right side: 19V (should be 240V :?:) . Not good. I check the meter. It's digital and gives me an error code. I look up the code and immediately get confused. A call my electrical supervisor at work and give him the low-down. "Not good." He says. "Call the utility company."

While I wait for the utility company to show up, I take a moment to reflect on the day, knowing the worst of it is behind me. (It's not.) Back to my blown-up and put-back-together switch for a moment. What I failed to realize when I swapped the red wires on the switch was that Rancilio followed a very standard convention when handling 240V in a machine. One hot circuit (or "line") is black and 120V to ground. The other hot circuit is red. Also 120V to ground. The way you get 240 is line to line voltage. So, hook a black or red wire to one side of the heating element and ground the other side and you've got 120V across the element. Hook black on one side and red on the other and you've got 240. Great. No problem. Got it. What they did that confused me a bit but I have no excuse for at all is that they didn't seem to follow this convention on the load side of the switches. The way they wired the brew switches goes like this. Black wire (120V line) in on left side of switch. Red wire (load) out to solenoid on left side of switch. Red wire (120V line) in on right side of switch, brown wire (load) out to pump controller. So, switching the red wires in this scenario is a BAD thing. Solenoid gets hooked to pump (red to black) and left side of my circuit breaker gets hooked to the right side. This is called a line to line short. This also causes plastic switches to explode. Don't do this. While a switch may be "rated for" 240V, it's not rated to short circuit 240V inside of it.

So, all that leads me to no power at all once the utility company arrives and tells me that I have a fried transformer. Luckily, this happens occasionally, and they gladly accept ownership of the problem and chalk it up to one too many wind storms or lightning strikes. For dinner, I decide to warm up some left over mashed potatoes in a 3Qt saucepan. Since we have no power, I opt for the Webber gas grill. After a half hour of indirect heat, the potatoes are ready. I grasp the stainless steel handle of the saucepan and turn my body 180 degrees to place the incredibly hot pan on a hot pad on our patio table. I notice halfway through the swing from the grill to the table that I am destroying the flesh on my hand. Saucepan on range, cool handle. Saucepan closed inside 350 degree grill, dangerously hot handle. I learned many years ago that EMTs often dress moderate to severe burn wounds with rags soaked in vinegar. Mustard is mostly vinegar, with a creamy emulsion of mustard seed to hold it in place, turmeric (which has amazing healing properties) and salt, which helps mustard closely match the body's salinity and makes it sting less. My hand healed up remarkably fast...
LMWDP #704

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#14: Post by Jake_G (original poster) »

Chapter 6: The Hubris sets in

Well, after failing in my best attempts to either electrocute myself or set myself on fire, I finally got both groups working, although to this day the right group solenoid still rattles when I use it. It turned out to just be a little assembly error that indirectly lead to my 2nd degree burns and blown transformer, but hey, go big or go home, right? It's now June or July of 2012 (2013). We have used the machine in the garage for the last several weeks to get used to it and we decided it was time for a permanent home inside. We just finished ripping out the cabinets of our laundry room so we could plumb in the machine. We used the laundry room for a few distinct reasons:

1: I get up early in the morning and the laundry room has a door, which keeps the grinder from waking up the family.
2: The laundry room has the needed water supply and drain in close proximity to...
3: 220V power is readily available from the dryer. I actually have my machine wired into the lugs on the back of the dryer for a clean install.
4: What better reason too rip out your cabinets and paint the laundry room than to install commercial espresso equipment on top of your annoyingly tall (because of their pedestal drawers) front-load washer and dryer?

Here we are. Plumbed commercial machine sitting happily next to our Mazzer Super Jolly with burrs made out of the same alloy they use to machine the cutters for end mills. Who needs good espresso when you have good espresso equipment? It turns out that bragging rights don't taste any better in the cup if you don't put them to good use. I'll get into the root cause of the problem a little later, but suffice it to say that with a rotary pump, and it's instant-on flow charactarististics, preinfusion just isn't happening. Since I can't explain why it was important before with Francis, I can't come up with a good reason too keep doing it. I do the water dance flushing routine, and I just don't have time to worry about pre-infusing on the commercial machine. It's no longer part of the routine. Five years more go by and I'm just ignorantly sitting on the cusp of mediocrity. I guarantee you there are folks out there with a Starbucks Barista and a Solis grinder making espresso that is actually drinkable. Not me...

Fun stuff happens over the years, and I get a kick out of making things work, so I get plenty of opportunities to bring dying machines back to the land of the living. One such example (along with quite a few Barista machines, if I find one for less than $40, I just buy it instinctively...) was the aforementioned Gaggia Baby. A good friend of ours received it from a good friend of theirs and they had never used it or even intended to use it. While tearing it down for the typical "this hasn't been cleaned in years" service, i realized that this was a machine from the mid '70s! It needed a good descaling and a few o-rings but what a tank of a machine! Adjustable temperature switch, 3-way valve, cool aluminum boiler with integrated heating element. Pretty much the same ingredients you get in any Gaggia from the last 40 years. They build them to last. My sister-in-law and her husband still use this machine daily and it never lets them down.

Another great example was our first Silvia, which we didn't get until early 2015. I found it for $200 with a Baratza Encore grinder, Whole Latte Love tamper and some other goodies. I cleaned it up and experienced Silvia for a few weeks, but after having the S20, I just couldn't get attached to her. A friend and coworker of mine gladly took her and the Baratza off my hands, but I kept the temper and use it to this day :D.

More coffee boringness took over after Silvia's departure until 3 months ago (it was 4...) when something astonishing happened...
LMWDP #704

User avatar
TomC
Team HB
Posts: 10534
Joined: 13 years ago

#15: Post by TomC »

It's nice to have a variety of dialogue on HB and you write very well! I look forward to each post. Your journey somewhat mirrors my own. Every coffee machine/grinder I own has essentially been paid for by buying, fixing then selling something else.
Join us and support Artisan Roasting Software=https://artisan-scope.org/donate/

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#16: Post by Jake_G (original poster) »

Thanks for the kind words! My hope was there would be a few folks who could relate as I put this all together and maybe a few more that just get a kick out of what a total nut job I am. It has been nothing if not fun over the years and I've had a blast writing each post. It is nice to have a community of like-minded folks with whom I can share the journey. Everyone at work always thought I was crazy (I'm pretty sure they're correct...) but I always had that little glimmer of "yeah, well at least I don't weigh my shots" (I'm gonna go pull an 18 gram triple, slayer style) :roll: .

It is crazy, though to be at this for so long and realize just how much you don't know. It's back to work for me this week (had last week off for the holiday) so I'll have to find a sustainable rythm for checking in and hopefully contributing to other topics where my experiences can lend me to being helpful.

Cheers!

- Jake
LMWDP #704

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#17: Post by Jake_G (original poster) »

Chapter 7: To have loved and lost
It pays to have friends. Especially when they know you are a certain kind of nuts.

It's now July, 2017. Just over 4 years have past since I started being better than everyone else. (I've adjusted the dates in my other posts, I was off by a year! :shock:) I get a call from a friend, who has a friend that has "some sort of shiny coffee machine with a big nose on the front of it" that doesn't know how to use it and doesnt care to learn. "I thought maybe you might be interested."

Uh, yeah.

I might be intested...

So, there it is. The machine that forever changed my espresso experience. It isn't much. To be honest, it's probably one of the least prestigious E61 home machines ever; a Euro2000 Junior. But...
-52W Ulka Pump, Check
-1.2L Boiler, Check
-E61 style manual group, Check
-Heat exchanger, Check
-100% Stainless steel frame and body, Check.

I could go on. So here I am with a pour-over vibe pump E61 machine. What to do? Obviously, I use it. The S20 gets a well-deserved break while we get to know Junior.

So here's the thing if you've never gone between a big, burly commercial machine and a smaller, vibe pump E61 machine. THEY'RE DIFFERENT.
-The S20 is ON. NOW. Junior is gentle, nurturing and calm.
-The HX in the S20 is HUGE. 180-200g cooling flush, minimum. Junior is much smaller, 60-100g is plenty to calm the water dance.
-E61 Preinfusion is AMAZING. Watching the beads form on the bottom of the portafilter is not just a cool thing, my extractions were 100 times more consistent on Junior than I could ever get with the S20. Gone is the early blonding, the channeling, and the geysers. I had to grind finer. Oh yeah, the espresso tasted better, too. Hmmmm...

Why...

It's not possible that this crummy little machine can beat my big commercial machine that made me better than everyone else. It's just not possible. What the heck is going on here? We will get into that in the next chapter while I recover from what happens next.

I only get to enjoy Junior for about 6 weeks. I truthfully love this little machine, but the convenience of the plumbed S20 and the blood, sweat and tears poured into its rehabilitation. They make it hard to choose. I foolishly decide that I have no right to own both of these machines, so I do what any irrational maniac would do and list both of them for sale. I carefully list each of them for what my best guess of a fair market price would be so the market will truly decide which machine I will keep. Even though the S20 is a daily used machine in great working order, I just can't seem to get the interest that Junior is able to garner. Within a week, I have 4 serious buys for Junior lined out and one of them (who happens to be a senior designer for Behmor) comes through.

But alas, it truly is better to have loved and lost than to have never loved at all. Junior, in all his lack of pedigree, has opened my eyes to what can and should be in espresso. Is preinfusion the end all, be all? No. Excellence can be had through rigorous execution of a rock solid routine, regardless of the machine. But does preinfusion (among other factors) make it much easier to pull a consistently better than average shot? For this aspiring Home-Barista, yes. I still have so much to learn before I catch up to real time and even more so from there. I still don't know what pressure profiling is...
LMWDP #704

User avatar
AssafL
Posts: 2588
Joined: 14 years ago

#18: Post by AssafL »

Perhaps try to drop a size on the S20s gicleur?
Scraping away (slowly) at the tyranny of biases and dogma.

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#19: Post by Jake_G (original poster) »

Oh, I'm getting to that part in my story. If you want to have a chuckle, go ahead and look up the part number for the factory gicleur on an S20 and see if you can figure out what size it is...
LMWDP #704

User avatar
Jake_G (original poster)
Team HB
Posts: 4293
Joined: 6 years ago

#20: Post by Jake_G (original poster) »

Chapter 8: What's going on in there, anyway? Part 1

So, immediately after Junior finds a new home, I am determined to figure out why these 2 machine behave SO differently. I read. A LOT. I read every FAQ I can find. Through the resources section of this site, I find Randy G's website. I read all 17 years of Randy's blog entries and every last review and how-to (Incredible site, BTW). I learn about WDT. Proper dosing techniques, (crap, I'm overdosing!), I buy a scale (0.1g accuracy, of course!), I dose my grind per shot, I'm losing my mind!!!

So, in my reading I learnt some stuff. And I learnt some stuff that I haven't seen conveyed in a real tangible way in the past, so I'm gonna give it my best shot to lay out a few fundamental characteristics of the flow through an espresso machine in a way that hopefully makes some sense of why Junior is SO different from my trustee S20, and what I can do to close the gap. (Assaf was dead on the money, but there's more going on here.)

Ok. Fluid dynamics 101 with a couple preemptive notes:
First, I present my own incomplete inderstanding of subjects to the best of my abilities. While it is certainly not my intent to spread misinformation, my understanding is not infallible. What I present here is simplified, but based on recognized and generally accepted good engineering practices, so it should pass the sniff test with some rigor. Challenge what I propose if you think I've got something wrong; let's have some constructive discourse!
Second, as I search the Google for images to assist with this post, I invariably find images that originate from HB. As I use those images, I will post a link to their original topic to credit the OP.

Onward.
We all know that "The Golden Rule" says we should strive for a 60cc (2oz) double shot in ~30 seconds at 9 bar of pressure. We also all know that this is a starting point and that you can change the pressure, shot time and shot volume to suit your personal tastes, but the golden rule gets us close. So, we are targeting 120cc/min @ 9 bar.

The above image, first posted here, shows the performance curve of an Ulka E5 pump. The solid line shows the design curve, with the dashed lines representing the performance range of a properly functioning pump. A couple of the primary factors influencing the performance range of any pump are the inlet pressure conditions(water level, clogged inlet filter, kinked hose, etc...) and water temperature (hotter water requires more input energy than cooler water, and the pump loses efficiency). There are other factors at work as well, but in general, if a pump gives you a flow that is between the two dashed lines at a given pressure, it's safe to say it's working properly . Likewise, if the pump is generating a pressure between the two dashed lines at a given flow , it's doing its job, as well. Let's focus on pressure first...

Here we see that if we create conditions in our system (espresso machine path between the pump outlet and the puck) that result in the pump operating at 9 bar pressure, it will produce a flow between 200 and 325cc/min. That's way too much flow for brewing espresso. Between 2 and 3 times too much flow, since our target flow is 120cc/min. We need a way to divert between 80 and 200cc/min to someplace other than the puck. Hopefully this situation makes very clear the need for a high quality OPV. The OPV doesn't just vent a little pressure to make sure you don't exceed 9 bar, it diverts a substantial portion of the flow from the pump back to the reservoir. It's seriously important to being able to get a good extraction.

Without an OPV, you will end up grinding way too fine when attempting to get a 30 second double shot. If you try to choke the flow to accomplish 120cc/min, here's what you get:

In order to get all of the volume from the pump to pass through the puck at 120cc/minute, the system must create 10-13 bar of back pressure on the pump. Grind fine, tamp hard. It can be done, but it is not ideal, nor consistent.

I've often heard the argument that the OPV isn't really important and that you can just manage the back pressure with good technique, but I'm sorry, not so. If you have a puck that provides enough resistance to flow to generate (only) 9 bar of back pressure on the puck, you will likely have a 7 second shot. Likewise, If you get a 30 second pull without an OPV, you're likely extracting at nearly 12 bar. The problem only gets worse if you're like me and you shoot for a 30g ristretto in 35-40 seconds...

More to come...
LMWDP #704