Olympia Cremina 67 brew temperature adjustment

[oly_puller]

Hey all -
I've been reading here for about 44 of the last 48 hours... it's sort of the espresso version of The Matrix - you know, they plug Neo in and after a few minutes of what looks like a nutty dream his eyes pop open and he whispers, "I know Kung-fu" - well after burning the HB logo into my retina from staring at the screen so long - I went to my faithful "Precious" (my Cremina) and started checking a few things.

I suspect I'm brewing way too warm - maybe 210 or so...

My method for testing was unscrewing the spout on my pf, and poking my digital thermometer up there without a basket and releasing some water. Does this sound like a good way to go in the absence of a real tester with a tiny thermal sensor? If it is, my thermometer read 210.

I think my shots are fine, but I do worry that they are bitter -which makes sense if my machine is running warm... anyhow, I don't want to leave anything on the table as it were... taste wise that is... so I want to try and get this solved.

My questions are to all of you who own or have restored a 67 - 1) is my test sound and 2) if it is, how much of an adjustment is needed on that screw back there (inside the machine) to take the temp down? Is it a slight turn for a big temp change or a big turn for a slight change?

I'll tinker with it until it's right - but I'd sure like some pointers from those that know!

Thanks a bunch!
Pt

[HB]

I've been reading here for about 44 of the last 48 hours... it's sort of the espresso version of The Matrix- you know, they plug Neo in and after a few minutes of what looks like a nutty dream his eyes pop open and he whispers, "I know Kung-fu"...

I always thought of HB being more like Morpheus' question:

"
"Blue or Red Pill?" from BentTV Productions (humor)

In fact this little quip was on the home page for awhile and then the Resources page:

"After this there is no turning back to local cafes. You take the blue pill, the story ends, you wake up in your bed and believe whatever you want to believe about coffee. You take the red pill, you stay in Espresso Wonderland, and I'll show you how deep the rabbit hole goes... Remember, all I'm offering is the chance of a godshot, nothing more."

It seemed funny at the time... returning to your comments, recall that the water entering the group is literally boiling; the grouphead acts as a heatsink to reduce it to brew temperature. I've measured the in-basket temperature of the Microcasa and Cremina and they both have profiles that rocket up and then descend fairly rapidly:

Steve and I plan to do more extensive measurements once his Cremina is up and running. I expect it to behave much like the Microcasa, where the key to getting the desired brew temperature isn't the boiler pressure setting, it's the current temperature of the grouphead. Sitting idle warms the grouphead and diminishes its ability to act as a heatsink, as does drawing water through it. The trick is (a) allow the appropriate amount of time for the machine to warm up and not much more, (b) draw enough water through to finish warming the group, and (c) pulling your shots before the grouphead goes overtemp.

For the Microcasa, (a) is about 12 minutes, (b) is a half-shot, and (c) is about three minutes from start to finish. The thread Using the Olympia Cremina covers the same steps with considerably more detail.

[oly_puller]

Well that makes sense too... hmmm... so - maybe leave the dial alone for a bit.

Really then - how the heck would I know if I'm brewing at the right temp without the little thermal meter thing?
It seems to me that with all the variables, it's almost impossible to tell what's going on since I'm working in the vacuum of my own experience.

I know I'm measuring 14 grams of ground espresso - I have a scale.

I know I'm tamping around 30#'s - easy to measure.

I can see by the puck that there are no freaky holes or cracks so I'm assuming the water is infusing properly -

That leaves, Temp, Grind, Bean Freshness and Pressure as the variables that might effect me.

I own a Rocky grinder that's in pretty good shape. I've used it long enough to know how to dial my grind anywhere from gusher to stall.

The beans are an issue - I don't really have a near by roaster that I know of... I'm working on that.

The pressure is good I think - my technique matches that described in the "using the cremina" thread...

So - I'm left with temp... and education... I suppose I'll need to keep tasting and decide what I think is tasty- I look forward to your tests.

Thanks for the reply!

Pt

[HB]

So - I'm left with temp... and education... I suppose I'll need to keep tasting and decide what I think is tasty- I look forward to your tests.

That's precisely the point. Taste is what matters, not what a meter says.

There's an extra challenge with lever-type machines because they rely on the group as a heatsink - you are trying to hit a moving target. Once you've used them for awhile though, you can brush your fingers against the grouphead and know if it needs to be warmed up, is ready, or is over temperature (what I call ready for "cappuccino worthy" espresso only). Those who want precise, no-brainer operation will be frustrated with lever machines. Others appreciate the hands-on ritual they offer. It's nice to have a lever and semi-automatic so I can choose depending on my mood. When executed correctly, lever shots are unlike anything from a vibe pump machine -- figuring out why there's a difference and the suspicion that the pump is the key has been an intriguing topic lately...

[oly_puller]

I thought about the comments I've read and what you wrote about the group head being a heat sink...

But I think there's something I don't quite understand- not thermal dynamics - though that's some tricky stuff... What I don't quite get is the adjustment of the micro switch controlling the boiler.

If as you suggest that after a few shots, a machine gets too hot and then shots are really only suited to be mixed with milk, then doesn't it make sense that the machine should be dialed down and then have blanks run through until the head is *up* to temperature - so that all shots from there on our will be consistently good?

Also - as a side note... I think sometimes this over analysis starts to get in the way. Take last night - I was pouring what I call "alter boys" - they aren't really anywhere near a god shot, but they were respectable. This morning I couldn't help the temptation to measure my water temp with the method I described earlier in the thread... next thing you know I'm tweaking things here and there - adjusting my grind changing beans and I got nothing but tar black gushers with 1/8th inch pale crema! I could pay 3.95 at the green mermaid if I wanted that!

Well - if anyone has an specific info on determining *how* to make sure your Cremina's micro switch adjuster dial is dialed in correctly, I'd love to hear about it - I sort of feel like I have too many variables right now - Is my grind right? Are my beans fresh? Did I tamp properly? Are my expectations too high? And for crying out loud, how come my crema doesn't look as coppery as that in the pictures I keep seeing all over this site...

I think I need a double.
Pt

[HB]

If as you suggest that after a few shots, a machine gets too hot and then shots are really only suited to be mixed with milk, then doesn't it make sense that the machine should be dialed down and then have blanks run through until the head is *up* to temperature - so that all shots from there on our will be consistently good?

Yes, there probably is some lower setting that would do what you suggest, although it's likely that the steaming would suffer enough to render cappuccinos impossible. Some lever users "cheat" by unplugging the machine and thereby delaying the problem of overheating; it works because the small boiler can come up to steam temperature very quickly (steam pressure is required to force water out of the boiler).

You have to admire the ingenuity of it -- an espresso machine that produces excellent espressos AND cappuccinos without waiting. The only drawback is the overheating issue we're discussing, which isn't important if you're preparing drinks for one or two people. It's curious how many home baristas chose machines like Rancilio Silvia / Gaggia Classic, which can't steam and brew at the same time, and yet they have no need for more than two or three drinks in a given session. I owned a Silvia and it wasn't easier to use than my Microcasa...

PS: I agree with your point about analysis paralysis. It's even more true with lever machines, which by their very nature resist methodical analysis. Patience and enjoyment of the learning process are prerequisite characteristics of a happy lever machine owner.

[oly_puller]

Yeah - I had a Francis X1 and got rid of it returning once again to my Cremina - I'm ashamed to admit I was enticed by the X1 - It was a gift, but I thought the ease of flipping switches and using <gasp> pods, would be something to look forward to. Bahhh!!! After standing around for 3 or 4 minutes trying to steam some milk - let alone trying to keep it from turning out like my daughter's bubble bath - I decided it wasn't for me.

Funny thing was - I was perfectly content with my cremina until I started surfing the web... heck - it's just like golf... or anything else. There are some basics - past that, you got to find your own groove.

Thanks for the advice and the observations. As for the temp adjustment... I've realized through a pm on this site that my pressure switch, while it was effecting my temp slightly, has nothing to do with the temp of my boiler!!! Doh!

For those that care, it turns out there is a small thermovalve on the *bottom* of the machine to adjust the temp!!! And all this time I was fooling with the pressure... HA!!!

Here's a quote from Steve -

-- The temp is regulated by the thermovalve on the bottom. the one with the emergency cutoff switch...the red one. It is set to cycle at a specified temp. The best way to really check temp is with a thermocouple in the portafilter.

Anyhow- I'll adjust my machine as close as I can to the right temp now and await my thermocouple testing do-dad.... You couldn't really expect me to slack on dialing it in... I mean, it's not really analysis paralysis if you're making progress - right??

Best!
Pt

LMWDP #30
(wooohoo!)

[espressoperson]

Some of my empirical findings that may relate to this thread...

Seven or eight minutes initial heating till boiler light turns off.

One to two minutes additional heating after releasing pressure. Machine can stay in this pre-release state for a long time without overheating. So I try to leave this step till just a few minutes before I'm ready to pull my first shot.

One pull to heat grouphead and portafilter. Usually between two to five ounces because portafilter is cold and lever is hard to move quickly so more liquid gushes through.

One pull to bring to operating temperature. Less liquid here because portafilter is now warm and lever can be moved more quickly, with less chance of overheating the portafilter.

First shot perfect.

Second shot perfect or very good.

Third shot sometimes but not always a little bitterness and some burnt crema ring around the cup.

Fourth shot the same.

None of these shots are necessarily sink shots for me or my non-coffeegeek guests.

Shutting machine off for even brief periods of time will increase the quality of successive shots.

If the machine has been left on for a long time, a quick flush through the portafilter will improve the shot versus straight shot without a flush. But better not to leave it on. (Either way it's probably gonna be one of HB's cappa-only shots)

Some of the notes in this thread imply the Cremina can reach or maintain a state of equilibrium. IMO the machine is more predictable than it is controllable, and you can learn to work with that predictability to increase the quality of your shots.

I'm looking forward to whatever data can be provided on temperature during shots and over successive shots. While it may not be necessary for mastery of the machine, it can't hurt, and IMO it will allow us to eke even more quality out of our machines.



MichaelB
LMWDP #24

Olympia Cremina 67
Mazzer Mini
100% Thor Fittings (No plastic!)
----

[timo888]

I have lowered the p-stat on my Cremina 67 quite a bit, which has greatly extended the amount of time the machine can idle before the directly attached group becomes too hot to function as an effective heat sink. I turn it on before dinner, release the false pressure, and forget it about until after dinner. If the machine feels a little hot after a leisurely meal, to cool it down before pulling the shot I release some steam, which lowers the water temperature in the boiler. Or, if I want to pull a shot before the machine is fully warmed up, I release the false pressure into the empty portafilter to heat it, give the lever three or four shallow semi-lifts after the heating element light has gone off; this action circulates water through the group, heating it, with no water exiting from the dispersion screen. Plenty of steam for a couple of cappas or lattes despite the low p-stat setting.

Regards
Timo

[chopinhauer]

Hey Timo, your post prompts me to ask a question about pressure and temp in creminas.

I'm coming off years of using a old and simple pavoni europiccola, you know the ones from the early 80s that have just two swiches, high temp and low temp, and no pressure stat. I had that machine down pat, especially the steaming aspect, where I could steam as little as 60mls of milk into silky microfoam.

Well after switching to a 1973 cremina 67 a month ago I have encountered a fairly steep adjustment curve, especially when it comes to steaming small quantities of milk. It is much harder to do this without burning the milk because the increased steaming power of my cremina. What you write prompts me to think that perhaps I might have more success by turning the p-stat down to decrease the steam power. Is that a correct assumption? If I do turn it down then how low can I go before affecting the pressure for the purposes of making coffee? For, as you know, the cremina 67s don't have pressure gauges therefore one has to do adjust the p-stat by trial and error.

Oh, and one more question. I know where the p-stat is on the cremina, but which way does one turn the round dial in order to turn the pressure down? Looking at the back of the machine, to the left? or to the right?

thanks

[roadman]

Oh, and one more question. I know where the p-stat is on the cremina, but which way does one turn the round dial in order to turn the pressure down? Looking at the back of the machine, to the left? or to the right?

My apologies to whoever had the page I lifted this pic from. Copied it to my hard drive ages ago and can't remember who the original poster was.
Jon

[chopinhauer]

Thanks, well that pic certainly answers my query in the CLEAREST possible way. Thanks for pointing it out to me.

[timo888]

Well after switching to a 1973 cremina 67 a month ago I have encountered a fairly steep adjustment curve, especially when it comes to steaming small quantities of milk. It is much harder to do this without burning the milk because the increased steaming power of my cremina. What you write prompts me to think that perhaps I might have more success by turning the p-stat down to decrease the steam power. Is that a correct assumption?

Yes, lowering the p-stat does reduce the force of the steam, making the process more forgiving when smaller quantities of milk are involved.

If I do turn it down then how low can I go before affecting the pressure for the purposes of making coffee? For, as you know, the cremina 67s don't have pressure gauges therefore one has to do adjust the p-stat by trial and error.

How low you set the p-stat is partly driven by personal taste. I have had a great cup of espresso with a Terroir roast at 195°F and like to have my p-stat set so that at the bottom of the heat cycle, I can get temps in that cooler range. According to the steam tables, boiler water temperature at .7 bar is ~194°F. At .8 bar it is 200°F. At .9 bar it is 206°F [though these temps need to be adjusted for atmospheric pressure and the attentuating effects of the group: 1.7 bar is 239F; 1.8 is 242.5F; 1.9 is 245.5F in the boiler.]

You can rig up a pressure gauge temporarily to do this calibration -- there is a picture on the H-B website that Steve Robinson posted a year or more ago. For best results, follow his approach and not the quick-and-dirty approach where you attach the gauge to the steam outlet. You will need an adapting coupler in either case, to go from the NPT thread on the gauge to the thread on the machine.

Regards
Timo

P.S. Olympia used to have a (pricey ) pressure-gauge boiler cap combo but I cannot find the part at the moment on their website.

[roadman]

You can rig up a pressure gauge temporarily to do this calibration -- there is a picture on the H-B website that Steve Robinson posted a year or more ago. For best results, follow his approach and not the quick-and-dirty approach where you attach the gauge to the steam outlet.

Just curious, any reason for recommending one method over the other?
Jon

[timo888]

If you attach the gauge to the boiler, you can bleed off the 'false pressure' using the steam wand, and you can test the steam at the chosen p-stat setting more easily.
Regards
Timo

[roadman]

Seems to me you could lift the lever up and relieve the false pressure that way, no?

[timo888]

Seems to me you could lift the lever up and relieve the false pressure that way, no?

The lever draws water to the group via a tube which extends all the way down to just above the heating element at the base of the boiler. The air would remain trapped at the top of the boiler.

Regards
Timo

[roadman]

If you attach the gauge to the boiler, you can bleed off the 'false pressure' using the steam wand, and you can test the steam at the chosen p-stat setting more easily.
Regards
Timo

Actually Dan and I just did a pressure test on the machine a couple weeks ago. The Cremina 67 does not have a pressure gauge on it but we were able to hook one up right off the top of the boiler.

There is a thumbwheel at the base of the pressurestat that allows you to adjust. I have decided to keep mine at 1.1-1.2

We found that the machine is very stable with its pressure. We did a couple tests to see how much pressure fluctuated between cycles and it all stayed within a .1 range. At the range we picked you get great steam and solid pressure for your pulls.

I think this is the picture you're referring to from Restoration of an Olympia Cremina thread. Am I missing something or are you referring to another project?
Jon

[timo888]

I remember seeing a pressure gauge hookup where the steam wand was still operable, but perhaps I am conflating more than one memory, Steve Robinson's pictorial essay with another. But in any case, if you don't release the false pressure your reading could be off, though I don't know by how much--the difference could be negligible.
Regards
Timo

[karolos]

<image>
My apologies to whoever had the page I lifted this pic from. Copied it to my hard drive ages ago and can't remember who the original poster was.
Jon

Actually this is a picture from the resources section of my website FreshCoffeeShop.

No apologies needed

I own an Olympia Cremina 67 for one year and I've written about my experience and some tips in a quite lengthy article (where this photo is located)

Lowering the pressurestat and blocking two of the steam wand's holes has worked best for me.

I would like to also recommend using the OKS 1110 as a lubricant for the group.

Friendly Regards
Karolos Tsiligirian