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Thread: Water distribution disk for Mokita Combi

  1. #1
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    Water distribution disk for Mokita Combi

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    I have read on the Pullman site, that Greg made a water distribution disc for his Imat/Nemox/Quaha machine.

    Does anyone have any thoughts on making one of these?

  2. #2
    KJM
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    Re: Water distribution disk for Mokita Combi

    Well, oh Ducky one, I have an NS Oscar sitting on the bench with a "Pod" style dispersion disc and screen.* My problem is that I cant seem to get an answer on "can I get an Oscar dispersion disc" from anyone in Australia...

    So Ill take the chunky hunk-o-brass that is the pod disc and just kiss it off on a lathe.* The dispersion discs are nothing more than a piece of brass (usually) with a bunch of holes to let the water through and (maybe) some kind of ridge on the top/bottom to confine the water.

    Id imagine any machinist could fab one up for you if you have the relevant dimensions.* Getting the right sized brass blank would be the big challenge..

    /Kevin

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    Re: Water distribution disk for Mokita Combi

    Im curious, where is this dispersion disc supposed to go, between the shower screen and the boiler base yeah?

    On my machine there is very little space as the shower screen screws directly to the boiler base. I did think about machining some channels into the brass on the base but havent done it yet...

    Would love to hear more on this topic though!


  4. #4
    KJM
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    Re: Water distribution disk for Mokita Combi

    Quote Originally Posted by 2A313B33073A37363C580 link=1310896217/2#2 date=1310992714
    Im curious, where is this dispersion disc supposed to go, between the shower screen and the boiler base yeah?
    Disclaimer - Im not an espresso mechanic. More a bush mechanic ::)

    If you search (google) for sectional views of the grouphead youll discover that the water is delivered via a small oriface and squirts down. The dispersion disc screws into that and diffuses the water down. So the 9bar squirt hits the top of the disc and spreads across the top and through holes in the disc downwards. The showerscreen screws into the disc and further spreads the water over the puck (and prevents excess grounds going up).

    On my Silvia, there is probably no more than 0.5 to 1mm gap between the bottom of the disc and the showerscreen.

    Does that help? I suspect your machine probably has a disc and it is stuck on...

    /Kevin


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    Re: Water distribution disk for Mokita Combi

    Aaaah yep, Ive had another look at the exploded view and I see that the little plug with four nozzles (dispersion block) that the shower screen screws into is removable (fat chance) from the boiler.

    I was thinking of machining some shallow channels into the surrounding brass to aid the dispersion further. I might be barking up the wrong tree though!

  6. #6
    KJM
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    Re: Water distribution disk for Mokita Combi

    You would hope that the engineers who designed it got it right in the first place (and then the bean counters made it cheaper :-) ).

    I suspect you dont actually want too much of a gap or channel size (DANGER! KJM is not into fluid dynamics) - the typical holes Ive seen in the discs are 1mm or so in size and pressure is 9bar. So there is a heck of a potential for "squirting" (another KJM technical term...). I suspect making grooves to improve the dispersion might make things worse. But if youve got a spare disc or can make another it might be worth a crack!

    Just my $0.02.

    /Kevin

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    Re: Water distribution disk for Mokita Combi

    Thanks for your thoughts guys.
    I will have to ponder, and maybe find a machinist.

  8. #8
    KJM
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    Re: Water distribution disk for Mokita Combi

    So - have you been able to remove the dispersion disc from the machine? On both the Oscar and Silvia it basically falls off in your hand when you undo the showerscreen screw. Good to take it out and give it a clean..

    /Kevin

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    Re: Water distribution disk for Mokita Combi

    Quote Originally Posted by 64464141424E49465342436352444C270 link=1310896217/0#0 date=1310896217
    I have read on the Pullman site, that Greg made a water distribution disc for his Imat/Nemox/Quaha machine.

    Does anyone have any thoughts on making one of these?
    I too have pondered on this upgrade for my Quaha.* Keeping a keen eye out for a suitable brass disc, I eventually found one at Bunnings. It is a brass decorative plate on $3.65 bathplug! The brass plate is very thin and pliable, and the center hole sits it perfectly inside the showerscreen (mine is of the newer design). Simply remove the plate and trim it to a desired diameter (1/2-1/3 of screen diameter?), then drill some holes in it. I find there is less evidence of channeling when using the disc. The only thing I am a little hesitant about is the alloy of this brass, i.e if it is of potable quality. Some brass alloys can contain lead...

    Id be interested to hear what others think of my solution.



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