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Thread: Gaggia Classic - general troubleshooting/improvement

  1. #1
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    Gaggia Classic - general troubleshooting/improvement

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I'm trying to methodically sort through all of the information on this forum and elsewhere and come up with a prioritised list of things I can do to my entire coffee process to improve my espresso. I was hoping to get some thoughts from you all on whether this list seems reasonable, is in the right order, that sort of things sorting the essential improvements from the nice-to-have hobby upgrades.

    The background to this is that I've just recently disassembled my 9 year old Gaggia Classic and done a deep clean and service, replacing seals as necessary. I had a spare portafilter so I grabbed a hole saw and took the crotch out of it. I had a few good pours, but these were the exception. Lots of jetting, lots of blonding, or conversely nothing but a few drops of tar dripping through. I played around with the grind a bit but in cleaning on basket with a pin, I think I may have damaged a few of the holes and ensured jets will always blast through these.

    I've changed my grind size right down as per most people's recommendations, and getting some half decent results, but I'm getting very sloppy, wet pucks now where as before I used to get nice, solid dry ones that you could pick up and handle easily. Because of the fineness of the grind, I now find I'm unable to tamp anywhere near as hard as I would have thought was required (haven't tested pressure on scales yet, but will do asap).

    Machine is a Gaggia Classic
    Grinder is a De Longhi KG100

    ALREADY DONE


    1. Use a clean, well serviced machine with filtered water.
    2. Use fresh coffee, preferably less than 2 weeks after roasting.
    3. Good, fine grind on a half decent grinder
    4. Upgrade steam wand to Rancilio Silva v2
    5. Naked portafilter
    6. Disassambled steam valve, cleaned, put back together


    PLANNING ON DOING

    1. Replacing double shot basket
    2. using scales to test tamp pressure
    3. Testing/adjusting OPV
    4. PID temp control
    5. Prewarming coil


    THINGS I DON'T PLAN ON DOING
    1. Upgrade grinder
    2. Upgrade machine

  2. #2
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    Quote Originally Posted by pcqypcqy View Post
    Grinder is a De Longhi KG100

    <snip>

    THINGS I DON'T PLAN ON DOING
    1. Upgrade grinder
    The grinder is by far the biggest limiting factor in your setup. Why is upgrading not an option?
    A $99 Sunbeam EM0440 would be a noticable improvement

    I'm the last one to recommend upgrading equipment for minor (or fashionable) reasons but the KG100 type grinders are fundamentally unsuited to grinding for espresso as upper the burr carrier is insufficiently supported for the loads generated by espresso grinding
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  3. #3
    Mal Dimal's Avatar
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    Agree...

    Upgrading to a decent grinder would realise significant improvement in the cup.
    The De Longhi KG100 is more suited to where maintaining consistent (micron size) grind size isn't as important as it needs to be with espresso...

    Mal.

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    Understand re: grinder. I'm trying to tick through the list and knock off the items that won't cost me much money at this point. $100 is more than I'd like to spend right now.
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  5. #5
    Senior Member LeroyC's Avatar
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    Quote Originally Posted by pcqypcqy View Post
    Understand re: grinder. I'm trying to tick through the list and knock off the items that won't cost me much money at this point. $100 is more than I'd like to spend right now.
    But if you do the first five things on your list you'll spend $100 anyway. Even if you buy budget option for all these you'll spend that much and it'll essentially be wasted money as you'll still be limited by a crappy grinder. I'd be looking for a good 2nd hand small conical burr. You should be able to get something for under $100. Your options would be - Sunbeam EM0480, Breville BSG800, Nemox/Imat Lux, or if you're really lucky an Isomac, Iberital or Lelit might pop up.
    As someone who's been in your exact position I can vouch that the grinder makes the single biggest difference of all the things you want to do.

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    Quote Originally Posted by LeroyC View Post
    But if you do the first five things on your list you'll spend $100 anyway. Even if you buy budget option for all these you'll spend that much and it'll essentially be wasted money as you'll still be limited by a crappy grinder. I'd be looking for a good 2nd hand small conical burr. You should be able to get something for under $100. Your options would be - Sunbeam EM0480, Breville BSG800, Nemox/Imat Lux, or if you're really lucky an Isomac, Iberital or Lelit might pop up.
    As someone who's been in your exact position I can vouch that the grinder makes the single biggest difference of all the things you want to do.

    Interesting.

    I really want to improve my technique with what I have. I already have the PiD, a short length of copper I can scrounge for the pre heat, etc, so these projects aren't really costing me much and are easy to implement.

    But out I'm more interested in people's opinions of the impact of the other possible improvements and in what order I should do them.

    I know the grinder is important, but I guess I'm reluctant at this point because I wouldn't want to spend money on something that I may just replace, I.e. I'd prefer to save that 100 for the inevitable purchase of a proper grinder like a mini mazzer.

    Little projects that I can do one at a time and only cost a few dollars I can justify to the missus, buying a new appliance I cannot, not at least until this grinder proves to be totally worthless.

    I have access to some of the grinders mentioned, so I might borrow one to compare the results.

  7. #7
    Mal Dimal's Avatar
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    I'd opt for the PID Controller first as this will realise the most impressive improvements not only in the responsiveness of the machine, but also results in the cup since you will be able to literally 'dial-in' the brew water temp. to get the best from the bean being used at the time. The Controller can improve the Steam performance as well, to such an extent, that you will notice improvement in milk texturing.

    After you've got experience using the Classic with the PID Controller, you can then look at more subtle enhancements like the Pre-Heat loop around the Boiler, etc...

    Mal.

  8. #8
    Senior Member LeroyC's Avatar
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    Aaah ok, so you've already got a PID. You might as well install it seeing as you've got it. If you can adjust the OPV as well that will be worthwhile. It's essentially free to do, but make sure you use a pressure gauge to do it. Trying to do a blind adjustment on the OPV is pointless. You may have read that a 270deg turn will set the OPV to the correct position. This is often true, but not always, and unless you get the pressure down below 10.5bar static there's no point. Having a pressure gauge will help you with any fine tuning.

    Also the copper coil is really only necessary if you're planning on making multiple coffees frequently. The recovery time between shots on a Classic is usually around 4min. It sounds a lot, but it's not hard to fill in 4min, so if you're only making 1-2 coffees at a time most of the time then the copper coil is unnecessary. The single biggest improvement in the quality of extractions you get will still be achieved by getting a better grinder so if you can try some without having to buy one then I'd say definitely give it a go.

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    Coffees are made 2 at a time on my machine, one for me and one for the wifey, both doubles in a 14g basket. We used to do them nearly back to back, but now I'm trying to leave more time between shots, occasionally flipping the steam switch on for a few seconds to help recover the temperature. Though without a readout of the temp, this is all guesswork. The pid will help with this a little bit.

    I'm planning on setting up a pressure gauge, not sure if I'll install it in the machine or make up a portafilter style gauge with a tap to get the dynamic pressure. Anyone have thoughts on this? I guess you only need to adjust the opv once, but then there's the cool factor with the dial gauge on the front of the machine as well.

    i backed off the grind this morning and tamped harder, got a similar extraction but a drier puck. These beans are getting old though, about 3 weeks. Fresh ones arrived earlier this week.

  10. #10
    Mal Dimal's Avatar
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    Quote Originally Posted by pcqypcqy View Post
    We used to do them nearly back to back, but now I'm trying to leave more time between shots, occasionally flipping the steam switch on for a few seconds to help recover the temperature. Though without a readout of the temp, this is all guesswork. The pid will help with this a little bit.
    A PID Controller, properly installed and setup, will obviate the requirement to wait between pulling shots. The Classic responds particularly well to this type of Mod' as it has a high Power to Water Volume ratio in the Boiler which allows it to be very responsive to a PID Controller's outputs. This is also the case for (dry) Steam production too...

    Mal.

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    EDIT - did another autotune and it seems to have settled down now and holds the set temperature better without overshooting.

    PID went on yesterday. I'm struggling to tune it. I've let it warm up to about the operating temperature, and then selected auto tune. It doesn't seem to realise that if it heats at full power right up to the set point that it will overshoot by 10 to 15 degrees celcius. It seems to be quite good at catching the falling temperature, clicking on and off as the temperature falls to the set point, at most dipping 1 degree below, but the overshoot is killing me at the moment - spouting steamy water out the group everywhere.

    Anyone familiar with this device? I feel like there's a setting somewhere that I can change so that it will undershoot rather than overshoot.

    It's a cheap knock off Berme Rex C100 from china. The manual I have is in mandarin, and the other manuals I've seen online are all in Engrish so I'm struggling to understand what each parameter is actually for.
    Last edited by pcqypcqy; 19th September 2015 at 10:00 AM. Reason: for fun
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  12. #12
    Mal Dimal's Avatar
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    With machines like the Classic that use a particularly small Boiler, you're probably better off using the Autotune feature after the machine has warmed up somewhere close to normal operating temperature, rather than from cold. You can do this more than once, as you've already tried, and then as a matter of interest, you can then go into setup and see what final parameter settings have been settled on, and record these for reference.

    After using the machine for a few days, you can then determine if further fine tuning may be required. The main thing to remember when attempting this, is to only adjust one parameter at a time and perhaps use something like this or this as an aid to determining what needs to be adjusted...

    Or, you could just head back in here and see if one of us can help you out...

    Mal.

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    http://www.fmfranklin.com.au/products/data/rkc/c100inst.pdf

    Not sure if this is your exact one but the symbols for the settings should all be similar. Out of interest what did the auto tune set the PID settings to?


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    I've attached a photo of my pid for reference. I will get a project box for it today. Values are below. I did a few auto tune routines, most were near the set temp to begin with. My theory is that it needed some sensible values to begin with so it could home in on something that works, so each auto tune got me a bit closer.

    Set Value is 95 currently. My probe is taped to the side of the boiler, away from the elements, with a big blob of thermal paste. Most people seem to have temps set in the low 100's, but that just gives me boiling water or steam out the group. I'm varying the temp a few degrees to find the sweet spot, and I'll dig out a glass thermometer to try and measure the temp coming out of my naked portafilter.

    I think the probe placement away from the elements means that the boiler shell at that location is more influenced by the water inside rather than the elements. I'm not saying that this is better, just noting the difference.

    I did it this way so I could reverse my installation and out the thermostat back in if I want. The thermocouple is much larger than the thermostat was, so didn't want to drill and tap just yet.

    P 67
    I 527
    d 131
    Ar 6
    T 1
    Sc 0
    Attached Images Attached Images

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    So now in installing the project box I've somehow stuffed something up. I think there may be a loose connection somewhere in the thermocouple. The screen is reading some temperature above 1200 deg C and flashing. If I reverse the polarity of the thermocouple wires it just flashes "oooo" at me. I had some issues like this when I first installed it the other day and jiggling the wires at the PID end seemed to help, but now I've stripped the dodgy crimped connections off and have just put the wires into the mounting screws. My multimeter tells me there's a voltage across the wires, so I'm not sure what's going on.

  16. #16
    Mal Dimal's Avatar
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    Yep....

    Sounds like your t/c has gone "open circuit". May be easily rectified depending on where the break is. Best to do a close inspection along the t/c from whoa to go to see if you can locate it, otherwise a new t/c will be the only way out... By the way, you can't join a broken t/c cable/wire as such, rather you need to shorten the t/c back to the break and create a new t/c junction.

    Also, just taping the t/c to the Boiler somewhere is not a great idea, regardless that you've used thermal interface compound. You really need to screw it to the top of the Boiler using one of the t/stat mounting screws if possible; and the TIC too of course.

    Those PID parameters all look a bit odd to me also but until you have a working t/c and it is mounted solidly and securely, will be better to wait until you've fixed that side of things up.

    Mal.
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    Ha ha, I solved this problem.

    The thermocouple as a braided metal outer covering over the wires. Turned out this was brushing one of the SSR contacts, so every time the PID was powered, it was getting an extra 40mV through the thermocouple, which turned sensible temperatures around 3mV / 90 degrees C up to around 1200. I re-ran the wires ensuring no contact and problem sorted.

    Why do you say you need to screw it in - so long as it's reasonably secure and thermally connected to the boiler, isn't it going to give you consistent results?
    Last edited by pcqypcqy; 21st September 2015 at 06:53 PM.

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    Borrowed a Mini Mazzer. Is pretty good!

    Still getting some jetting out the naked portafilter and very wet pucks. Almost looks like there are 4 spots where channeling occurred, corresponding to the 4 holes in the shower screen holding disc.

    Any tips on where to go from here?

  19. #19
    Mal Dimal's Avatar
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    Quote Originally Posted by pcqypcqy View Post
    so long as it's reasonably secure and thermally connected to the boiler, isn't it going to give you consistent results?
    Well mate, would you tape your CPU Cooler down and reckon it's good enough?

    You can't get a reliable thermal connection using the amount of force that a piece of tape provides. You want reliability, you need to have it properly fixed to the boiler. Up to you of course...

    Mal.

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    It's a different problem. CPU cooler needs good thermal contact to transfer heat into a heat pipe/sink and fan arrangement, and needs to continue doing so whenever it's on. I'm simply trying to measure a temperature. I know it's not a permanent fix, but the blob of thermal paste and the tape are still there so I'm happy with it for now, at least until I can assess how the pid is performing before I commit to drilling out the thermostat hole.

  21. #21
    Mal Dimal's Avatar
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    It's up to you mate but what would I know...

    Mal.

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    I've been playing with an arduino lately and have finally worked out how to measure the voltage coming from the PID controller to the SSR, i.e. how often it gets switched on and for how long each time. Will play around with some settings and do some more measurements and put an update on here in a few days.

  23. #23
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    Hello! Newbie here. I pulled my Gaggia Classic apart and cleaned it after buying it used. It hasn't seen a lot of action in its lifetime but was pouring very slow shots. I took it apart and cleaned every possible part according to recommendations here. I unscrewed my OPV valve but did not record how many turns it took to remove from the body. Anyone have any idea how far it should be turned down to function. So far I have been trial and error and no luck. I don't have a pressure gauge or blind cup to test? Any suggestions or know factory settings????

  24. #24
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    Quote Originally Posted by cwhiteley View Post
    Hello! Newbie here. I pulled my Gaggia Classic apart and cleaned it after buying it used. It hasn't seen a lot of action in its lifetime but was pouring very slow shots. I took it apart and cleaned every possible part according to recommendations here. I unscrewed my OPV valve but did not record how many turns it took to remove from the body. Anyone have any idea how far it should be turned down to function. So far I have been trial and error and no luck. I don't have a pressure gauge or blind cup to test? Any suggestions or know factory settings????
    Best to just get hold of a pressure gauge. Trial and error even with a blind filter is a roll of a dice at best by measuring output. Tighten it up clockwise and back out 2 or 3 revolutions should get you somewhere ideal but that is just a guess.



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