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How repeatable are scace aquired E61 offset settings?
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Discussions > Espresso > Machines > How repeatable...  
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 715
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Tue Sep 10, 2013, 4:12pm
Subject: How repeatable are scace aquired E61 offset settings?
 

How repeatable are scace acquired E61 offset settings from one machine to the next that on the same model?

I apologize for starting this, but I am pretty convinced that my offset on my machine is off by a few degrees. I don't want to say it is yet though because my test device is homemade.

First, I used a blind basket that has a needled valve for flow control, and a layer of foam insulation to insulate the water flow from the cold basket and to somewhat simulate the coffee puck. I used a K thermocouple that seems to react very fast with my thermometer.  The photo below is an early prototype. It is still the same except I now have black foam insulation in the basket.

I calibrated my temperature by putting the probe in boiling water and adjusting for barometric pressure and altitude.

My flow is set to about 1.75 ounces in 25 seconds. It has been brought to my attention in another thread that coffee flow is not even throughout the extraction process... which I concede but I am not interested in engineering a variable flow control (other than just modulating the needle valve by hand).

Now, here is my dilemma... my offset was pre-determined by the importer. Do I leave well enough alone and assume it is correct or do I investigate this further? I have tested several times and I would place my temperature about 7-9 degrees low. Seems like if I let the machine set a while, it is 9F low and if I pull a couple of shots back to back it is about 7f low on the subsequent two shots.

I hope I a not opening a can of worms here... I openly concede that I am no expert, my tools are cheap homemade crap... but I still think there is no reason not to believe the numbers I am getting.

Edit: I also want to mention that I have also tested by pre-heating my entire PF and blind basket by dipping the entire assembly in boiling water before I made the test... my test results were still similar so I don't think the water temperature being measured is being affected by a basket that is not as warm as the group head.

DeanOK: scace_device_small.jpg
(Click for larger image)
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gz20tt
Senior Member


Joined: 17 Sep 2003
Posts: 93
Location: Melbourne, Australia
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Mazzer Super Jolly
Vac Pot: Bodum
Posted Tue Sep 10, 2013, 4:33pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

DeanOK Said:

How repeatable are scace acquired E61 offset settings from one machine to the next that on the same model?

I apologize for starting this, but I am pretty convinced that my offset on my machine is off by a few degrees. I don't want to say it is yet though because my test device is homemade.

Now, here is my dilemma... my offset was pre-determined by the importer. Do I leave well enough alone and assume it is correct or do I investigate this further? I have tested several times and I would place my temperature about 7-9 degrees low. Seems like if I let the machine set a while, it is 9F low and if I pull a couple of shots back to back it is about 7f low on the subsequent two shots.

I hope I a not opening a can of worms here... I openly concede that I am no expert, my tools are cheap homemade crap... but I still think there is no reason not to believe the numbers I am getting.

Posted September 10, 2013 link

I did a Scace check on mine when I had it set up.
I'm pretty sure we only adjusted the offset by a degree or so and my tech said that it probably wasn't worth doing much more as there are a fair number of other variables that will also influence the temp measured at the puck. We did several measurements back to back and were more worried about it just reading as stable. {Which it is - very nicely stable through a shot :) }

How's the taste of your espresso?
At 7-9 degrees low I'd expect a REALLY sour shot.
If it tastes fine - I'd leave it.

I didn't think I had the palate to taste 1 degree C differences, but I had a Yemen coffee I've been drinking that had a slight ashiness upon first sip. I thought I may have over-roasted it slightly and it was also aging (14 days old) as there was a bit of oil on it. I'd played with grind/dose with not much effect. BUT - a 1 degree drop , from 94 to 93 got rid of it. AMAZING! Ashiness gone, a little fruit returned.

Not sure if I've been much help with my ramble - but I do think that the taste result is more important that the number in the display. My fixes are just an up/down from where it's currently set, rather than nailing some "exact" value and also knowing that when I return to that coffee - on my machine in my house - I need to set it at X.
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 715
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Tue Sep 10, 2013, 4:40pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

gz20tt Said:

I did a Scace check on mine when I had it set up.

Posted September 10, 2013 link

Do you mind sharing what your offset is?

I do realize that a lot of things from air currents to room temperature can have some effect on the offset temperature.

As for taste, I am not good at describing the taste... I just know when it tastes good to me. The default setting was 203....and I have eventually worked it down to 200. I actually thought 203 was too high, but when I think back to the taste I had when it was running 203 its seemed really nice to me... so I think I will just split the difference between the display and the measured temperature and try it there for a few days.
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,462
Location: UK
Expertise: I love coffee

Posted Tue Sep 10, 2013, 6:14pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

DeanOK Said:

Do you mind sharing what your offset is?

I do realize that a lot of things from air currents to room temperature can have some effect on the offset temperature.

As for taste, I am not good at describing the taste... I just know when it tastes good to me. The default setting was 203....and I have eventually worked it down to 200. I actually thought 203 was too high, but when I think back to the taste I had when it was running 203 its seemed really nice to me... so I think I will just split the difference between the display and the measured temperature and try it there for a few days.

Posted September 10, 2013 link

Perhaps a different approach might suit you better, because trying to measure temperature in these types of devices is very very difficult. First there is an article I wrote, that will allow you to get to what 100C is on your machine.

Click Here (coffeetime.wikidot.com)

This will get you quickly into the ballpark of what's coming off the shower screen

gz20tt Said:

Not sure if I've been much help with my ramble - but I do think that the taste result is more important that the number in the display. My fixes are just an up/down from where it's currently set, rather than nailing some "exact" value and also knowing that when I return to that coffee - on my machine in my house - I need to set it at X.

Posted September 10, 2013 link

Never a truer word been said that what this poster said. It's also what I say in all my reviews of DB machines.

Then put away the gadgets:  Once you have your ballpark, get a coffee that's not roasted too dark or too light (colour of UK Cadburys milk chocolate), preferably a Brazilian. bring your PID temp down in increments to around 90C, it should be sour (if it is not then either your offset is too high, or the coffee has been over roasted and is quite dark). As you raise to around 92C, sourness should start to disappear and be gone by 93, by 96 bitterness should start to appear and get worse at 97 and 98C. In addition to that you will usually get a dark ring in the shotglass around the outer rim on the crema layer (too cool and the crema can be very pale).....adjust your offset so that the PID works well within a displayed range of 92 - 97C.

The objective is to get your PID in the region of 91 too sour 98 too bitter. Then using the logic of the poster above you work everything else out within that range for a particular coffee. From personal experience, you will work with most of your coffees within a 3C range. Adjustments required beyond this, normally mean your trying to make up for a poorly done roast. Your 93C with not usually be the same as someone else's 93C and you might need 94 on a friends machine even if it's the same model....but it doesn't matter.

If your going to be a real purist about wanting consistency, then like me you may want to do a small stabilisation flush before any sequence of shots, to start from a consistent state. I always pull 1oz through the group if I am coming to the machine after a time away, then I grind and tamp the coffee and I'm ready to pull the shot.

Beyond this there are so many variables that it doesn't matter what machine you use, things are not exactly the same. e.g. if I have the portafilter out longer than you because my grinder is slower or vice versa. Don't believe for a minute that the GS3 is better, it's not for other reasons. There was a temperature study done on the Duetto and it was on Home Barista, there was also one done on a GS3, I seem to remember the graphs showed the Duetto doing at least as well. The Duetto used a goldilocks formula for boiler size, thermosyphon pipe length and bore etc.. The QM pretty much follows this formula, which is unsurprising, since I told them what it was and I came up with it for the Duetto years before and told Izzo what they needed to build in terms of boiler sizing etc.. The temperature stability/characteristics between this and the Duetto are very similar.

As always taste should (must be your guide), can the machine produce a reproducible result...yes, is it temperature stable throughout the shot...yes, can it produce temperatures that are too cool and too hot, plus anything in between....yes

P.S Crema colour is an indicator, but equally pale crema can be cause by early blonding shots, poorly roasted coffee etc.. and it's a sad fact that overly hot shots can appear to extract better, look nice and gloopy with a nice dark rich looking crema. Often though you can taste that they were too hot and I have found a general tendency for people to set machines too hot for a particular coffee rather than too cool.
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 715
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Wed Sep 11, 2013, 10:54am
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

Funny.... Metropolis Coffee's recommended brew profile for the Redline is 200.5F. How the heck did they get that?  A half of a degree seems like they think these temperature indicators are accurate.
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,462
Location: UK
Expertise: I love coffee

Posted Wed Sep 11, 2013, 11:41am
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

DeanOK Said:

Funny.... Metropolis Coffee's recommended brew profile for the Redline is 200.5F. How the heck did they get that?  A half of a degree seems like they think these temperature indicators are accurate.

Posted September 11, 2013 link

It's called "Marketing" and it's all very unfortunate. I can't taste 0.5F and I don't know anyone who can, also as you say, one persons 200.% will be another persons 201 or 201.5 or 200 or ....the problem is a lot of this type of marketing hype, of coffee, machines, grinders, simply becomes "knowledge" in forums as people reinforce old myths. Unfortunately all the good stuff gets lost in all this marketing hype, because marketing hype is designed to be a seductive message.

e.g. I tell you about some widget/product etc.. to improve the taste of your coffee by 20%, I use attractive people, attractive kit, a seductive professional message, good photography a high price and a wannabe feeling. I then get it promoted by an experts or respected person.

or I refer you to this link, which costs you nothing, but a little bit of work to improve your espresso and it's free

Click Here (coffeetime.wikidot.com)

But it's not as much fun as a gadget/product, even though the product doesn't really clean behind the screen properly even when used in accordance with the manufacturers instructions, as I've proved.

The number of people who do what I recommend is a small fraction of prosumer machine users....the number who use a portafilter based powder cleaning product in the belief it does it all, probably a very large %.
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gz20tt
Senior Member


Joined: 17 Sep 2003
Posts: 93
Location: Melbourne, Australia
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Mazzer Super Jolly
Vac Pot: Bodum
Posted Wed Sep 11, 2013, 8:23pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

DeanOK Said:

Do you mind sharing what your offset is?

I do realize that a lot of things from air currents to room temperature can have some effect on the offset temperature.

As for taste, I am not good at describing the taste... I just know when it tastes good to me. The default setting was 203....and I have eventually worked it down to 200. I actually thought 203 was too high, but when I think back to the taste I had when it was running 203 its seemed really nice to me... so I think I will just split the difference between the display and the measured temperature and try it there for a few days.

Posted September 10, 2013 link

I'll have to look at my notes from the day I did the setup.

I also have a taste description issue - but I can sort of describe things in terms of burnt/ashiness and sour which is enough for me to know to bump the set temperature down or up.

Just to muddy things though - as a coffee ages - it does tend to lose some of the fruitier notes - and while the usual "fix" is to alter the grind a bit finer, we can now do a light temp drop :)
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gz20tt
Senior Member


Joined: 17 Sep 2003
Posts: 93
Location: Melbourne, Australia
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Mazzer Super Jolly
Vac Pot: Bodum
Posted Wed Sep 11, 2013, 8:34pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

DavecUK Said:

Never a truer word been said that what this poster said. It's also what I say in all my reviews of DB machines.

The objective is to get your PID in the region of 91 too sour 98 too bitter. Then using the logic of the poster above you work everything else out within that range for a particular coffee. From personal experience, you will work with most of your coffees within a 3C range. Adjustments required beyond this, normally mean your trying to make up for a poorly done roast. Your 93C with not usually be the same as someone else's 93C and you might need 94 on a friends machine even if it's the same model....but it doesn't matter.

Don't believe for a minute that the GS3 is better, it's not for other reasons. There was a temperature study done on the Duetto and it was on Home Barista, there was also one done on a GS3, I seem to remember the graphs showed the Duetto doing at least as well. The Duetto used a goldilocks formula for boiler size, thermosyphon pipe length and bore etc.. The QM pretty much follows this formula, which is unsurprising, since I told them what it was and I came up with it for the Duetto years before and told Izzo what they needed to build in terms of boiler sizing etc.. The temperature stability/characteristics between this and the Duetto are very similar.

As always taste should (must be your guide), can the machine produce a reproducible result...yes, is it temperature stable throughout the shot...yes, can it produce temperatures that are too cool and too hot, plus anything in between....yes

P.S Crema colour is an indicator, but equally pale crema can be cause by early blonding shots, poorly roasted coffee etc.. and it's a sad fact that overly hot shots can appear to extract better, look nice and gloopy with a nice dark rich looking crema. Often though you can taste that they were too hot and I have found a general tendency for people to set machines too hot for a particular coffee rather than too cool.

Posted September 10, 2013 link

Thanks Dave.
That's high praise coming from you :)

As a scientist myself - I get caught up in raw numbers way too easily.
In this case - taste and adjust accordingly is the best way forwards for me.

Agreed - my 93 will not be exactly the same as your 93 - machine to machine or even my machine at your house.

I love that you've categorically swatted the temperature stability issue and that aspect of the chest thumping that seems to occur on forums all over the place.

I use crema colour too as a tool for possible over/under extraction, hot shots or if I've ground too fine.
I think the too-hot thing might be that people are very sensitive to sour in their espresso and try to avoid it.
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,462
Location: UK
Expertise: I love coffee

Posted Wed Sep 11, 2013, 11:41pm
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

gz20tt Said:

I think the too-hot thing might be that people are very sensitive to sour in their espresso and try to avoid it.

Posted September 11, 2013 link

I am sure this is true also the current fashion for overly light roasting by some Artisan Roasters might well be another cause.
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MetropolisComm
Senior Member


Joined: 29 Jan 2013
Posts: 7
Location: Chicago
Expertise: Professional

Posted Mon Sep 16, 2013, 10:02am
Subject: Re: How repeatalbe are scace aquired E61 offset settings?
 

Hi Dean:

The recommended brew profile that we provide was developed by our coffee and training team (not a marketing firm) and is meant as a starting point and humble suggestion for working with Redline.  As you probably have found, Redline is pretty forgiving, and can yield a few different profiles depending on the parameters.

We've also recently released a single-origin espresso, El Salvador El Carmen Estate.  Hope you'll give this a try as well and let us know what you think.

Pax,
Seth
Metropolis Communications
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