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Sour shots, help!
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Discussions > Espresso > Q and A > Sour shots,...  
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RobCups
Senior Member


Joined: 28 Jun 2013
Posts: 11
Location: London
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Eureka Mignon
Vac Pot: Hario TCA-2
Posted Wed Jul 3, 2013, 3:46am
Subject: Re: Sour shots, help!
 

I don't think you really need a 14g basket so you can 'brew with less water'

I was just wondering whether water volume and dose could be reduced proportionately to produce a smaller espresso with the same flavours? As an analogy, when I brew with a cafetiere, or siphon brewer, or any other filter method, I change the coffee dose to match the water volume and the flavour extractions remain the same. Wonít this be the same for espresso, at least in principle?

The thermofilter will help you to see where you are, but the thermistor bead, or thermocouple, on the boiler will let you see where the boiler is and you can reproduce that temperature to reproduce the thermofilter temp.

Now that my thermofilter is working Iíve been able to take some readings. Initial experiments suggest my usual technique was way OVER the ideal temperature range Ė†around 102įC (215įF), suggesting that Iíve been mixing up my sour and bitter all along. That would be embarrassing. Iíd like to try a few more things before I conclude (smaller basket, another new coffee), but it seems fairly obvious that Iíve been over compensating for my imaginary temperature problem. Iíve just pulled two half-decent shots in a row, both more balanced and drinkable than my previous efforts.

I hadnít quite understood the relationship between boiler temp and water temp until Iíd pulled a few shots through the thermofilter. Before now, Iíve been letting the machine heat up for a long time on the steam switch, then pulling a shot as the boiler comes back down to about 106Ė104įC (thinking that the water temps would be about 10įC lower). The result was overheated water and bad espresso. It seems that a thoroughly heated Gaggia will produce water at about the same heat as the boiler, but this drops off pretty fast during the shot. Intrashot temps were better with a larger heat differential between boiler and boiler water, as AndyPanda shows in his video.

Apologies for anybody who feels Iíve wasted their time. I guarantee this is making a big difference to my espresso and I really appreciate your help!

All the best, Rob
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brianl
Senior Member


Joined: 1 Dec 2012
Posts: 480
Location: Chicago IL
Expertise: I love coffee

Espresso: Quick Mill Vetrano DB
Grinder: Baratza Vario
Drip: chemex
Roaster: Behmor 1600
Posted Wed Jul 3, 2013, 7:34am
Subject: Re: Sour shots, help!
 

Either way, you had an issue. Whether its bitter or sour is irrelevant.

How did you construct your thermofilter and what parts? I have the pid on the boiler but wanted to see what the temp was at the portafilter. I have a spare portafilter that i just keep the blank in for backflushing.
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RobCups
Senior Member


Joined: 28 Jun 2013
Posts: 11
Location: London
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Eureka Mignon
Vac Pot: Hario TCA-2
Posted Wed Jul 3, 2013, 8:56am
Subject: Re: Sour shots, help!
 

Hi brianl,

These are the parts I used:
ē Bottomless portafilter (link)
ē Cheap digital thermometer and thermocouple (link)
ē 14g basket (link)

Manufacture:
1) Clean the basket to remove grease/oil/dirt/coffee (so glue will bond well with metal surface)
2) Drill a hole in the basket for the thermocouple to enter, ideally from the lowest part of the wall or wherever you think the cable will fit when the basket is in the portafilter
3) Thread the thermocouple through into the basket, overshoot by approximately 29mm (half a basket diameter) to create the diving board shape described in step 5
4) Afix the thermocouple to the inner-wall of the basket with strong adhesive (JB Weld epoxy worked, as recommended by D4F). Glue up to the height of a coffee puck. Any higher and the glue will meet with the group head when locked in. I made this mistake and the glue was crushed down on first use.
5) Bend the excess cable down so that it hangs into the centre of the basket like a diving board. You want the bead in the centre of the basket, near the top of the puck. In theory, water is evenly distributed by your shower screen, so donít worry if itís off-centre.

Usage:
With the slightly springy cable and bead in the way, itís difficult to get a good tamp. When pressed down, the cable will spring back and ruin the top of your puck. Donít worry too much, you just want enough resistance to simulate the right water flow.

Some notes:

Iíve used it a few times now but already the glued thermocouple has come unstuck from the basket. If you follow my method, Iíd recommend making sure the basket you use is totally clean of grease/oils/dirt/coffee before gluing in the cable. Iíll be able to fix mine by cutting off the old glue with a scalpel and reapplying, but I wish Iíd spent a bit more time getting it right.

Having a bottomless portafilter handle means I can now switch between thermofilter basket and regular basket, so in a sense I just created a thermo-basket. If your pf isnít bottomless then youíll need to thread the thermocouple up through the handle first. Once glued to the basket you wonít be able to separate the two without breaking it. I guess this isnít a problem if youíre not planning to use the handle again.

The basket I used was ridged, which gave enough clearance at the bottom for the cable to hang. A ridgeless basket would be too close to the portafilter at the sides, so would require the cable to hang from the filter itself, which could be messy when brewing. Either way, make sure the hole is no bigger than required to fit the cable, as youíll want as much purchase on the cable to stop it ejecting itself under pressure.

If you decide to make one, let me know how you get on.

Rob
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Wed Jul 3, 2013, 9:17am
Subject: Re: Thermofilter
 

How about a picture, worth 1000 words?  You can post here, or add it to the DIY thermofilter thread

http://coffeegeek.com/forums/espresso/machinemods/622504

Are you sticking glue to the actual thermocouple wire/insulation of the wire?  Perhaps is will not adhere well.  I have a thermocouple that is water resistant insulation, but also seems glue resistant, thus the tube in mine, as the above thread.

Thermocouple with Teflon type insulation

Click Here (www.ebay.com)

or fiberglass

Click Here (www.ebay.com)

Edit, I looked at your link and it shows fiberglass insulation.  I an not sure that it glues well either.  I have seen them glued in with a large contact area.  You could bare the wire and glue that them, but you would need a different high temperature glue.  JB is electrically conductive IIRC, but very high temperature safe.  Most regular epoxy is insulating, but will soften too much, unless special high temperature.

 
D4F also at
http://www.gaggiausersgroup.com/
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brianl
Senior Member


Joined: 1 Dec 2012
Posts: 480
Location: Chicago IL
Expertise: I love coffee

Espresso: Quick Mill Vetrano DB
Grinder: Baratza Vario
Drip: chemex
Roaster: Behmor 1600
Posted Wed Jul 3, 2013, 10:29am
Subject: Re: Sour shots, help!
 

I ordered the recommended thermocouple thing you linked. I already had a few worthless baskets and a bottomless. So do you put coffee when you do this or does the epoxy cover as much as the coffee would? I have some high temperature epoxy laying around.
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RobCups
Senior Member


Joined: 28 Jun 2013
Posts: 11
Location: London
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Eureka Mignon
Vac Pot: Hario TCA-2
Posted Wed Jul 3, 2013, 10:35am
Subject: Re: Sour shots, help!
 

I used coffee, which is getting quite expensive, but it might be possible to epoxy up the majority of the filter holes in the basket instead? I havenít tried this.

I made another bad coffee this afternoon. I think I need to go back to monitoring water temps again until Iím more familiar with the temperature fluctuations. Itís annoying not being able to brew a coffee and monitor the water temps. Has anybody attempted to incorporate a thermocouple into the group head? I doubt I have the tools for such a job, but would be great to know if itís possible. Putting the bead behind the shower screen perhaps?

Rob
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Wed Jul 3, 2013, 11:18am
Subject: Re: Thermofilter
 

Brian, some ideas on hole size and what I've found on thermofilters

http://coffeegeek.com/forums/espresso/machinemods/622504

I will post there as the thread is about DIY thermofilters.  It is easy to search that way, my preference.

 
D4F also at
http://www.gaggiausersgroup.com/
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brianl
Senior Member


Joined: 1 Dec 2012
Posts: 480
Location: Chicago IL
Expertise: I love coffee

Espresso: Quick Mill Vetrano DB
Grinder: Baratza Vario
Drip: chemex
Roaster: Behmor 1600
Posted Wed Jul 3, 2013, 1:17pm
Subject: Re: Sour shots, help!
 

RobCups Said:

I used coffee, which is getting quite expensive, but it might be possible to epoxy up the majority of the filter holes in the basket instead? I havenít tried this.

I made another bad coffee this afternoon. I think I need to go back to monitoring water temps again until Iím more familiar with the temperature fluctuations. Itís annoying not being able to brew a coffee and monitor the water temps. Has anybody attempted to incorporate a thermocouple into the group head? I doubt I have the tools for such a job, but would be great to know if itís possible. Putting the bead behind the shower screen perhaps?

Rob

Posted July 3, 2013 link

Just get a PID. D4F is probably the most knowledgeable person on installing them and telling you what you need. Heck, even i can help. After you verify what temps you want with the portafilter probe you made, it's all easy street.

Sure it's probably going to run you about $100, but it's worth it because putting the thermometer probe on the front of the boiler is a hassle.
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RobCups
Senior Member


Joined: 28 Jun 2013
Posts: 11
Location: London
Expertise: I love coffee

Espresso: Gaggia Classic
Grinder: Eureka Mignon
Vac Pot: Hario TCA-2
Posted Wed Jul 3, 2013, 3:52pm
Subject: Re: Sour shots, help!
 

Just get a PID.

Okay, Iím listening, but I have questionsÖ

Iíve heard that a PID wonít help with my instrashot temp stability, but this video seems to suggest otherwise. What set up can you recommend and do your temps drop off much during a shot? Will I benefit from an alarm function, or do I just hit the steam switch before the shot?

I already have a thermocouple nicely positioned on the front of my boiler (a photo of my setup attached), but itís difficult choosing the right boiler temp to pull at based only on rate of temperature drop Ė a dark art that I suspect would be easy to forget once the thermofilter goes back in the cupboard. A PID may be the answer, but Iím not sure. Any advice or links to more information you recommend would be very much appreciated!

RobCups: gaggia1.jpg
(Click for larger image)
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Wed Jul 3, 2013, 4:21pm
Subject: Re: Sour shots, help!
 

You can control the drop but you need to understand how.  It is not the PID algorithms, but another function.  By now you have seen this thread

Click Here (coffeegeek.com)

and the PID thread.

http://coffeegeek.com/forums/espresso/machinemods/571792

The PID thread is a bit, lot, long as it was the idea to stabilize intrashot, developed.  The back half of that thread is a DIY Gaggia install with supplies and how to. I am happy to help if you have questions, but Brianl asked most of them there. He also overstated my knowledge, thanks Brian :)

 
D4F also at
http://www.gaggiausersgroup.com/
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