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Thread: New (Second hand) Gaggia Classic for a very very low price....Advice on mods?

  1. #1
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    Talking New (Second hand) Gaggia Classic for a very very low price....Advice on mods?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi folks, Im still pinching myself to make sure that im not in coffee infused dream, but on the weekend I managed to pickup a Gaggia Classic from a school fair for $5. Of course it went something along the lines of a beeline straight to the machine, street to the cashier and straight home to test the thing out! and much too my amazement it works perfectly. Ive already ditched the original steam wand and managed to make one up myself which is making texturing much better.Now for the questions! not that im looking to alter the thing for a while but I am interested in how much of a difference a PID will make to the overall control of the machine? I am aware of what a PID does but how much does it really change the taste of the shot, steam pressure etc? Ive attached a photo to show the custom steam wand for those who are interested and yes I realise the grinder isn't quite up to spec for the machine, however after some shims and experimenting im getting 30mls in 30 seconds with excellent crema so itl do for now

    IMG_0453.jpg

  2. #2
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    Great bargain there!

    Theres plenty of threads already on PIDing.
    You will get the nay sayers (usually probably never tried it) that will tell you that you should learn to use the machine in its current state and a PID really does not make much difference.

    I will tell you that it makes a massive difference. After using a stock standard Gaggia for about a year then going to PID the difference is chalk and cheese.
    The big benefits are consistency, much quicker recovery time, which leads to better steaming. No need to guess where the machine is at in its temp cycle, no flushing or chasing optimal temp.

    I can taste the difference changing the temp setting on PID by one or two degrees all other things being equal.

    Intra shot stability is only marginally improved, this is mostly affected by the groups ability to hold temp. However as soon as you start the shot the PID begins to try and rectify the error which does not happen without PID unless you like flicking your steam switch off and on.
    I only loose a couple degrees on a double ristretto style shot in a minute or 2 the temp is relatively stable again.

    I say work on upgrading your grinder first, this is where , (myself included) most people will notice a big change in there espresso


    http://coffeesnobs.com.au/brewing-eq...eyond-pid.html

  3. #3
    Senior Member Dragunov21's Avatar
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    If you're comfortable messing around with it beyond bolt-on kits, EBay has plenty of PID + Thermocouple sets and PID + Thermocouple + SSR sets for $15-35.

    I've sourced some brass M4 standoffs that I should be able to drill through and mount the thermocouple bead in with epoxy.

    eBay link removed per the http://coffeesnobs.com.au/general-ne...icy-rules.html


    I'm toying with the idea of drilling through the existing thermostat mount hole so it penetrates the boiler, allowing the thermocouple to be in direct contact with the water and therefore react far quicker than if it were measuring the boiler housing temperature.

    I figure that it will keep the water inside the boiler at a very stable temperature and then kick the element on as soon as you start a flush/pull, keeping it on until the whole boiler contents is back at setpoint, which should be just what we want with this machine.

    By only concern is whether the boiler pressure might be great enough to make it difficult to prevent leaks if it's penetrated...
    Last edited by Javaphile; 27th March 2013 at 10:24 AM. Reason: eBay link removed
    Graeme likes this.

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    Quote Originally Posted by Dragunov21 View Post
    If you're comfortable messing around with it beyond bolt-on kits, EBay has plenty of PID + Thermocouple sets and PID + Thermocouple + SSR sets for $15-35.

    I've sourced some brass M4 standoffs that I should be able to drill through and mount the thermocouple bead in with epoxy.

    eBay link removed per the http://coffeesnobs.com.au/general-ne...icy-rules.html


    I'm toying with the idea of drilling through the existing thermostat mount hole so it penetrates the boiler, allowing the thermocouple to be in direct contact with the water and therefore react far quicker than if it were measuring the boiler housing temperature.

    I figure that it will keep the water inside the boiler at a very stable temperature and then kick the element on as soon as you start a flush/pull, keeping it on until the whole boiler contents is back at setpoint, which should be just what we want with this machine.

    By only concern is whether the boiler pressure might be great enough to make it difficult to prevent leaks if it's penetrated...
    Good luck with the drilling inside the boiler. There are a one or two threads on the USA forums on such ventures.

    I did the K type thermocouple originally with the drilled out screw on the Sestos PID. I then went a bought the Auber custom RTD $25. Well worth it IMO, much more sensitive and quicker to react. I ran auto tune a couple of different ways, the best and what i have stuck with is letting the machine heat up for a good half hour 107 degrees, then preparing an actual double shot and just as im about to lock in the PF i reset the AT function to run again.

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    Re: New (Second hand) Gaggia Classic for a very very low price....Advice on mods?

    Talk about a bargain! Even with an (expensive) PID kit, you'd still come out in front!

    From what I understand of autotune algorithms (which is to say, what Ive been told by someone who writes them), they work best when run at approximately the desired setpoint, as the behaviour of the system at this temperature is what matters most.

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    Il have a look at those pid kits on flebay, relatively handy with electrical stuff so installation shouldn't be too hard. More or less you can set the temperature of the pour?/ steam? And yeah for $5 it was the bargain of the day haha, was missing the portafilter but I had one from my old 70s gaggia baby that fits and too be honest I trust the espresso coming out of the classic over the 30 something year old baby. As for the grinder, I was lead to believe if you were getting good shot times and good crema there wouldn't be much difference between a top of the line grinder and a cheapy? Im guessing grind speed, burning the coffee, inconsistent grind? Thanks guys

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    Senior Member Dragunov21's Avatar
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    I'm using a Breville CG10 which I've modified to a grind that gives ball-park (60ml in 20 seconds) results. I'll have a Baratza preciso by the end of today so I'll let you know how much of a difference I'm finding with it.

    As for autotune, my advice would be to start off with a small proportional gain value and integral gain (or wide proportional band and long integral time, depending on what your PID uses) which should be the default settings as they come from the factory. This should allow it to control to setpoint.

    Once this is done, start your autotune then pull a shot, then once your temp has stabilised at setpoint pull another shot, and repeat until the time between pour and stabilisation isn't getting any shorter. Then, stop your autotune. I'm not certain that this is how the autotunes will work, but it would be my educated guess. The reason you want to do it that way is because stabilisation between shots is what you're trying to achieve so you want to tune it to that specific disruption.

    The only thing to watch is that you aren't overshooting your desired temp when starting the machine up, because when tuned for the small temperature drop caused by pulling a shot, the integral function may be excessive when faced with the 6-minute-or-so initial heat when turning on a cold machine (google integral wind-up). If this happens, you can back off the integral, power-cycle the machine when it first reaches your desired setpoint (thus resetting the integral) or if you can figure it out, set your integral anti-windup setting to suit.

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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by Steve82 View Post
    Good luck with the drilling inside the boiler. There are a one or two threads on the USA forums on such ventures.

    I did the K type thermocouple originally with the drilled out screw on the Sestos PID. I then went a bought the Auber custom RTD $25. Well worth it IMO, much more sensitive and quicker to react. I ran auto tune a couple of different ways, the best and what i have stuck with is letting the machine heat up for a good half hour 107 degrees, then preparing an actual double shot and just as im about to lock in the PF i reset the AT function to run again.
    Was it that tricky? =/

    Might just mount the TC in the screw and put some hat-transfer paste in then... I'm planning to cannibalise my Cafe Roma for its thermoblock anyway which should render any extra benefit moot.

    I would use the RTD but my PID was a leftover from a previous project and s locked into using 0-400C K-type TCs

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    Quote Originally Posted by Dragunov21 View Post
    Was it that tricky? =/

    Might just mount the TC in the screw and put some hat-transfer paste in then... I'm planning to cannibalise my Cafe Roma for its thermoblock anyway which should render any extra benefit moot.

    I would use the RTD but my PID was a leftover from a previous project and s locked into using 0-400C K-type TCs
    I would not know how tricky it is to drill inside the boiler and i have no intention on finding out. Very happy with how well the Auber RTD is working.
    As i said there are threads out there i found them by accident while researching PID stuff in general, i seem to remember seeing someone having success with it? using a larger brass probe with a high pressure seal, i guess its just a matter of finding the right bits.

  10. #10
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    Hi folks thought id give everyone an update. Got a pid from flebay and did the install. Enjoying mucking around with the temps. Quick question though ive noticed on the forums people setting them up at around 106 at the pid. When ive done this the machine just splurts out watery steam from the brewhead, instead setting it to around 99 is about right. I still need to do some actual thermometer in a cup measurements to find the sweet spot (around 94 or so?). Also when I set a new temp should I do another autotune? and when I do an autotune should I run any water through or just leave it alone completely. Sorry for the all the questions, just had it in a few days and trying to get my head around mucking around with it. Cheers

  11. #11
    Senior Member Dragunov21's Avatar
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    It depends on what your usual usage is. My PID is set with a ~17C offset I think (so you set the setpoint to the required extraction temp but the boiler's controlling to 17C higher than that); I'll check tomorrow.

    Quote Originally Posted by Dragunov21 View Post
    With a little testing (ok, two hours) last night involving a bit of sponge, a calibrated TC and a 100-time-extracted puck, my process is like this (albeit on a Gaggia Classic, not a Silvia).

    With the PID set to a given temperature (92-96C), from any heated/overheated state, topping up the boiler through the steam wand then flushing a shot and waiting 1.5-3 mins will result in the next shot starting at <1C below setpoint. rising <0.5C above and dropping <0.5C degrees below throughout a 60ml shot, measured at the puck.

    Discard the puck and give three quick pulses to flush the showerscreen then wait at least 1.5 minutes, up to 3, and the next shot will be dead on setpoint, dropping <0.5C over the shot. This is indefinitely repeatable.

    It takes me ~1:30-1:40 to weigh, grind, dose and tamp so it works out perfectly. It's a bit artless, but it allows me to pull as many shots as I want without waiting before starting on milk.



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