tuning temp profiles on stock (0.8mm) gb5

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tuning temp profiles on stock (0.8mm) gb5

Postby Jimmy Oneschuk on Wed May 09, 2007 6:13 am

Does anyone out there know how to get a temp profile that begins at 201, then trails down to 200 or 199? I'm getting climbing profiles over here on an .8mm gb5.

With the scace I normally give it a few seconds flush to get things up, otherwise it starts much lower than this.

There must be something I'm doing wrong - I thought the new group caps alleviate this drop?

Thanks in advance,
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Postby Philip Search on Wed May 09, 2007 3:00 pm

It sounds like you are having one of the same problems we were having at the scaa show. Was your machine banged around abit in shipping? Sounds to me like the mix water coming in is not being dispersed properly, or the element is not cycling right. If I understand correctly, there is a cap/hat thing that helps with the water dispersion, and when it slips off the PID doesnt work right. This is also the case with clovers (acording to Jason from clover). I have never seen this part, but I will tell you that on the machine Iad problems with at scaa, nothing would get the temp to stop from rising durring the brew cycle from 3-5 degrees, which is not normal to the Marzoco I have here, or the one in the roastery.
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Re: tuning temp profiles on stock (0.8mm) gb5

Postby Andy Schecter on Thu May 10, 2007 2:30 am

Jimmy Oneschuk wrote:Does anyone out there know how to get a temp profile that begins at 201, then trails down to 200 or 199?


That's easy: get a heat exchanger machine.

On the other hand, a slightly rising temperature profile is characteristic of the dedicated brew boiler machines (LM, Synesso)....
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Postby Jimmy Oneschuk on Fri May 11, 2007 5:43 am

Er, Andy but a profile that begins at 197, then goes up to 201, 202?

I'd be okay with a temp profile that bumps up and down a few decimal points during the curve. But at current, I'm getting shots that underextract during the first third and overextract during the last third.

Philip, thanks for the heads up - I need to get ahold of someone in Seattle, and hopefully the problem is an easy mechanical fix.

Cheers,
Jimmy
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Postby Jimmy Oneschuk on Fri May 11, 2007 6:36 am

Added a video of the profile on a scace 2.0

Note: the pull is done after a 4-6 second flush - with no flush the temp is even cooler.
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Postby nick on Fri May 11, 2007 6:50 am

Jimmy,

Rather than inserting the Scace and turning the group on, try this: turn on the group (flush), and while it's running, fill the Scace basket-area with water and then lock-in the Scace (while it's running).

As we've been reminded by this year's USBC middle-machine, the Scace approximates the flow-resistance of coffee, but it does not (nor is it designed to) replicate a "real extraction." Using the technique I mentioned above might give you a faster brew-water reading on the thermocouple.
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Postby Jimmy Oneschuk on Fri May 11, 2007 11:13 pm

Sounds good, I will give that a try. Thanks for the tip.

I had a chat with Roger at ESI. I've got 0.6mm gicleurs on order, to see if this changes things a little bit, and then make programming tweaks, etc, later. What I notice with my shots is I don't get super dark pours during the first 10 seconds of extraction, but the last 10 doesn't blond much either... and of course, the shots taste terrible and underextracted. From what I see on the scace seems to make sense when observing the real deal.

Often, after 3 or 4 pulls, I will get a shot with a darker first third, and beautiful tiger stripes with that nice orange oil/spice balance I love from the Epic.

I will keep on keepin' on...
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Postby Brian Ludviksen on Mon May 14, 2007 2:42 pm

Just a thought, but were you sure to bleed the group heads before checking the temp?
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Postby Jimmy Oneschuk on Mon May 14, 2007 9:50 pm

Groups were bled during the install...

Perhaps this should be performed again?
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Postby Brian Ludviksen on Tue May 15, 2007 7:03 am

It never hurts to bleed the groups in my opinion and all you need is a 5mm Allen wrench. I usually notice >1 degree variance in temp on GB and FB La Marzoccos. Most of the time, any variance more than that can be resolved by bleeding the group heads or heeding Mr.Cho's advice on using a Scace; making sure there are no pockets of air when you insert the Scace that could throw off your readings.

Good Luck!
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Postby barry on Tue May 15, 2007 9:47 am

Bludviksen wrote:making sure there are no pockets of air when you insert the Scace that could throw off your readings.


also, you need to let the scace heat up in the group before starting the measurement. heat up, pull out, flush group, wipe scace, reinsert, and test.
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Postby Andy Schecter on Tue May 15, 2007 6:44 pm

Jimmy Oneschuk wrote:Er, Andy but a profile that begins at 197, then goes up to 201, 202?


No, you're right, that kind of temperature rise seems abnormal. Seems like a machine problem, although a bigger flush may help somewhat.

Jimmy Oneschuk wrote:I'd be okay with a temp profile that bumps up and down a few decimal points during the curve. But at current, I'm getting shots that underextract during the first third and overextract during the last third.


There are two things that seem peculiar here:
1. The posts by Nick and Barry almost imply that if you could just get your Scace Device preheated so that it read a little higher at the beginning of the shot, your espresso would improve. I'm sure Nick and Barry don't mean it that way, but such thinking -- tweaking one's Scace Device technique to get the "proper" result -- is a dangerous diversion. It sure won't result in better espresso.
2. I've always hated the terms "overextract" and "underextract." They vastly oversimplify the situation by pretending the multi-dimensional espresso extraction can be evaluated on a one-dimensional scale. But even given that, what does it mean to "underextract during the first third and overextract during the last third?" Espresso is ALWAYS underextracted during the first third....
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Postby barry on Tue May 15, 2007 7:55 pm

Andy Schecter wrote:1. The posts by Nick and Barry almost imply that if you could just get your Scace Device preheated so that it read a little higher at the beginning of the shot, your espresso would improve. I'm sure Nick and Barry don't mean it that way, but such thinking -- tweaking one's Scace Device technique to get the "proper" result -- is a dangerous diversion. It sure won't result in better espresso.



I'm not suggesting tweaking the device. I'm suggesting he follow SOP for the Scace:

WBC Procedure for Measurement of Brewing Water Temperature wrote:Specification: The espresso machine to be tested shall be at its normal operating temperature for 1 hour prior to testing. The portafilter containing the thermometer shall be inserted into the group during the warmup period.



If he's putting a cold Scace into the machine, he's going to get a slower temp ramp-up.
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Postby Jimmy Oneschuk on Tue May 15, 2007 8:02 pm

Andy, you're right on. The Scace is only there to give me empirical evidence of what's going on when I'm pulling shots.

Here's a better way of putting it: the majority of my shots don't start out as dark as they should during the first third of the pour. By the second third, the color is mostly maintained, and my the last third, it begins to blonde a bit.

Even with the suggestions for using the scace, the results still turn up the same, with an average 4 degree jump from start to finish. For 49th Parallel's Epic espresso, Vince recommends 200 deg F and 8.75 BAR.

I'm stumped. Is there anyone out there with a 0.8mm gicleur'ed GB5 that produces a very flat temp profile?

I have 0.6mm units on the way later this week from Seattle...

This crap has made life really difficult... if I can't figure this out soon, I'm feeling like pulling Epic off and switch to a single origin or something, because at the moment this beautiful coffee is going to waste! Not only this, it makes it difficult to train new baristas to pull good shots when you can't do it yourself!!
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Postby barry on Tue May 15, 2007 8:17 pm

Jimmy Oneschuk wrote:Even with the suggestions for using the scace, the results still turn up the same, with an average 4 degree jump from start to finish. For 49th Parallel's Epic espresso, Vince recommends 200 deg F and 8.75 BAR.


Have you tried bumping the temp up a bit to see what happens?
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Postby Jimmy Oneschuk on Tue May 15, 2007 8:18 pm

The Scace is unlikely to be cold - in most cases I'm testing blank shot after blank shot - so subsequent shots should leave the scace warm, (or so I'd think).

And yep, I tried that this afternoon, and it still starts at 197, then shoots up really fast to 205.

Which leads me to think there is a mechanical issue happening... perhaps re-bleeding the group might be one step to try?
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Postby barry on Tue May 15, 2007 8:39 pm

Jimmy Oneschuk wrote:Which leads me to think there is a mechanical issue happening... perhaps re-bleeding the group might be one step to try?


Maybe.


Could the spring in the pre-heat mixing valve be broken?
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Postby Jimmy Oneschuk on Tue May 15, 2007 9:38 pm

Hmmmm.... not sure. I'm totally unfamiliar with the mechanics behind the preheating system/mixing valve. Would there be a quick way to check?
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Postby barry on Wed May 16, 2007 8:34 am

Jimmy Oneschuk wrote:Hmmmm.... not sure. I'm totally unfamiliar with the mechanics behind the preheating system/mixing valve. Would there be a quick way to check?



I don't know... I was just looking at the parts diagram for the GB5, to see what mechanical could be causing a problem.
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Postby Jimmy Oneschuk on Wed May 16, 2007 8:48 pm

Tonight, after close, (edit: the mix valve I am referring to was for the spigot, not the mix valve for the groups) I closed off the water mix valve; thus water from the spigot is now unmixed and at maximum temperature. Prior to turning it off, I allowed for partial mixing, resulting in 185 deg F water (the temp I like for Americanos). From what I understand, under normal operation, the mix valve is automatically supposed to shut off the cold water during pump operation?

On the Scace, there was an immediate improvement in temp figures - still starts at 197 as usual, but moves a lot faster to 200 - in 2-3 seconds instead of 5-7 seconds, and the shots notably improve: much darker up front. When the temp does reach 200, it is very stable, only moving 1 degree during extraction. Right now, a 6-8 second flush, followed by inserting the pf immediately into the group (ie: I hold the loaded pf an inch from the group, while flushing, then turn off pump, insert, turn on pump). One needs to grind fine enough to slow the initial flow through the puck, which, from what I see happening, should bring the temp to 200 in that span until the first drips appear.

The Epic blend improves dramatically with this protocol - dark mottle shows up; the shots are full bodied and rich, and display great sweet orange/tangerine flavour against a nice chocolate/brown sugar background (ie not the sour tangerine you sometimes get from underexaction). These shots are pretty close to what I think is a perfect representation of Epic.

However, the shots I get with this process are what I'd call ristrettos (1.3-1.4 ounces in 35 seconds). When I attempt a 2:1 extraction ratio, the shots underextract - I believe the initial flow through the puck is too fast to stabilize the temp in puck at 200F. When I change over to 0.6mm gicleurs, I am hoping the softer pressure jump will allow for better "2:1" shots.

I have my fingers crossed the shots I pulled tonight are not anomalies, and they continue under normal operation tomorrow!!
Last edited by Jimmy Oneschuk on Sat May 19, 2007 12:12 am, edited 1 time in total.
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Postby Jimmy Oneschuk on Sat May 19, 2007 12:04 am

Okay, another update:

the improvements I've found wrt shot quality have more to do with eliminating time between flushing and inserting the PF.

Shots are still mostly inconsistent ie: 1/3 to 1/2 are acceptable. Consistency improves only with heavy use.
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Postby Andy Schecter on Sat May 19, 2007 1:40 am

Jimmy Oneschuk wrote:Okay, another update:

the improvements I've found wrt shot quality have more to do with eliminating time between flushing and inserting the PF.

Shots are still mostly inconsistent ie: 1/3 to 1/2 are acceptable. Consistency improves only with heavy use.


I'm not really familiar with what it looks like under the hood of the GB5, but...is there room to stuff some insulation around the gooseneck and group cap? It sounds like those areas cool down rapidly between shots (and flushes). If you could prevent the cooldown you might be able to get higher temps at the beginning of the extraction.
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Postby Marshall on Sat May 19, 2007 7:40 am

Andy Schecter wrote:2. I've always hated the terms "overextract" and "underextract." They vastly oversimplify the situation by pretending the multi-dimensional espresso extraction can be evaluated on a one-dimensional scale.


I don't think it is. When it comes to producing a cup in the shop or at home, this is cooking, not lab science. Brewing the coffee has to be approached in macro terms, because it is brewed one whole puck at a time, whatever the complexity of the individual components.

You can adjust different parameters for a sweeter or fruitier extraction, but the concept of "over" and "under" still remain useful.
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Postby Brian Ludviksen on Sat May 19, 2007 12:26 pm

I'm not really familiar with what it looks like under the hood of the GB5, but...is there room to stuff some insulation around the gooseneck and group cap? It sounds like those areas cool down rapidly between shots (and flushes). If you could prevent the cooldown you might be able to get higher temps at the beginning of the extraction.


If this is one of the GB/5 machines with a "hybrid" or "Pierro" cap design, then most of the areas that would cool down (the banjo tubing) are removed. However, if this is one of the first GB/5 machines that have group designs more like a Linea, then there is an "idle" area (the banjo tubing) where group water could cool and cause slight temp differences without proper flushing. If you happen to have the old group desing, I believe you can buy a retro-fit kit.




For what it's worth, I had two portafilters on a GB/5 3 EE at one of Ken Nye's Ninth Street Espresso shops and found the machine to be as consistant as it gets. I had two Scace devices on a 3 group EE, one on the far left group the other on the far right; both plugged into the same Fluke meter and ran the machine for 45 seconds. I took a picture after 30 seconds because I was surprised at the consistancy between the group heads...




Image


Although this shows the consistancy between group heads (on a 3 group machines) I also found that each group head maintained a stable temperature with less than a degree variance. Not bad in my opinion.
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Postby Andy Schecter on Sat May 19, 2007 1:35 pm

Marshall wrote:You can adjust different parameters for a sweeter or fruitier extraction, but the concept of "over" and "under" still remain useful.


Well, for instance, if the espresso is dominated by bitterness, is it over or underextracted? If it's flat and boring, is it over or underextracted? If it's grapefruit puckery, is it over or underextracted?

I'm not saying the over and underextracted terms are useless, I'm just saying that they don't seem to address a lot of common espresso faults. Maybe I'm just too dense to understand.
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