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Thread: PID - Any Sticky Thread?

  1. #1
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    PID - Any Sticky Thread?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Is there a CoffeeSnobs forum sticky thread on PID design/circuits/implementations? Already found some general discussions plus the PIDkits.com site. Thought Id ask as Ive just bought an Aldi $50.00 expresso machine to play with (butcher).

  2. #2
    Mal Dimal's Avatar
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    Re: PID - Any Sticky Thread?

    Gday PDP11,

    Welcome to CoffeeSnobs..... [smiley=thumbsup.gif]

    We dont have a Sticky for PID Controller implementation but theres heaps of info around about individual efforts, some of which you have already discovered. To give you an idea, here are the results of a simple Google site specific search that may provide you with a bit more reading material ;),

    Cheers,
    Mal.

  3. #3
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    Re: PID - Any Sticky Thread?

    a $50 aldi machine would be a thermoblock - i dont know how youd go pidding it. i havent had much experience with thermoblock machines but i imagine there is a hell of a lot of delay between control effort and output that a PID may very much struggle with. EDIT: scratch that - i think it would work ok, but the issue would be in the heat transfer characteristics to the water (ie, the relationship between the water temp and the thermoblock could be a bit wierd). its all a black-box system anyway so youll be finding an ideal "thermoblock" temp based on the water temp out of the block or by taste testing...

    also, dont forget that unless you have all the parts lying around already then youre going to spend far more than you spent on the machine in the process of pidding it.

    any issues with pidding (wiring, sourcing parts etc), PM me and i can help you out. ive done a few gaggias in the past so i reckon im reasonably well versed at the ins and outs of it all...

    best of luck.

  4. #4
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    Re: PID - Any Sticky Thread?

    My partner has a Rancilio Miss Silvia that is the real candidate for the PID. The Aldi is just going to be the warmup exercise. The Aldi doesnt even have to produce a decent coffee at the end of its conversion. In fact the taste of the Aldi expresso got the thumbs down before I even touched it. Therefore cost balance between the Aldi and PID isnt an issue.

    Dont want to make external changes like bolting on the PID display/switches onto the Miss Silvia or bringing out power/control wires through a hole in the case. Thinking of RF or powerline control. And if that wasnt stupid enough there is always an upgrade to WiFi and an embedded web server for the Internet.

    Only investigating options and planning at this stage. SiliconChip had a PID kit and there are lots of options for short RF links. Knowing the speed I work (wouldnt work in an iron lung springs to mind), might make some progress by next year. :-)

  5. #5
    Mal Dimal's Avatar
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    Re: PID - Any Sticky Thread?

    Hi again PDP11,

    There are many ways to go about this of course as most of us dont want to install an intrusive PID Control System, preferring to opt for a reversible installation that leaves no trace of the mod to any subsequent purchaser(s) 8-).

    This guy (Randy Glass) has a lot of excellent information including additional links to others who have approached the installation from different perspectives, so isnt a bad place to start when considering an approach that suits you. The actual hard-wired installation is pretty simple though and I cant see the need to add extra complexity but of course, each to his/her own. All the best mate and keep us posted with how you go.... :)

    Cheers,
    Mal.

  6. #6
    DONT USE
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    Re: PID - Any Sticky Thread?

    hi
    the aldi machines (not that you can call them that) have a very small s/steel / alloy boiler not a heavy brass boiler. this will give you very different results to the silvia. but yes gives you something to practise your mechanical / electrical skills on
    graham

  7. #7
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    Re: PID - Any Sticky Thread?

    Out of curiosity I pulled the machine apart to see how it heated the water and created steam. Answer is it has a cast aluminium boiler held together by 4 screws with an o-ring seal between the tank and base.

    The maker (maybe Shenzhen Orangehouseware Co. Ltd, China) states it is a 15bar expresso machine.

  8. #8
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    Re: PID - Any Sticky Thread?

    Behmor Brazen - $249 - Free Freight
    All I have done at this stage is replace the boilers mechanical thermostat by a thermocouple with simple control electronics. This is not a PID just a replacement of the mechanical device with a higher speed electronic control using first crack gap between on/off. Could go down to 0.25C for tighter control but there could be an issue of noise limiting accuracy plus the idea is to PID. Being under program control I can simply adjust temperature. *

    The graph in the attached file is the before and after fitting an electronic thermostat. Took a shot at about 840 seconds to see what the response of the electronic control would be. The two graphs are offset because I started the electronic control run at a lower temperature and it makes it easier to see what is happening. You can also see the effect of the group head/porta filter coming upto temperature from the changes in the period of the ramps.




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