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Thread: Home-made Portafilter (PF) Gauge for under $25

  1. #1
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    Home-made Portafilter (PF) Gauge for under $25

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    First Ive got to say that this NOT an original idea. I first borrowed this (more like an improved version of this) from Vicroamer to measure the OPV pressure a few months back. Havent thought about it anymore until the OPV thread from seedlings came and it got me thinking again. Below are everything you need to make your own PF gauge:
    1. PF with spouts removed
    2. Spanners - adjustable will do
    3. Pressure gauge - rated to 1600 kPA, 1/8" (or 6ml) BSP Thread
    4. Adapters to make the 1/8" fit onto the PF thread
    5. Plumbers tape

    I got the pressure gauge and adapters from Reece plumbing for a total cost of $21.50, $16 for the gaug and the rest for the 2 adapters. Plumbers tape 80 cents from Bunnings. If you bring your PF gauge along, the guys at Reece will be able to get the correct adapters which takes out the guesswork of what size and thread type to ask for.



  2. #2
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    Re: Home-made Portafilter (PF) Gauge for under $25

    Putting it together is no rocket science. Youll need to wrap the male threads with the plumbers tape at least a couple of times to make it watertight. Use spanners to grip the adapters and the gauge inlet because the cheap gauges are made of plastic and if you try to tighten the connection using the gauge face, youll break it. The only downside of this setup is the gauge is upside down and for some machines, you might not have a lot of space underneath the brew head which means you might need to get 90 degree type adapters. Mine was ok if I removed the drip tray.


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    Re: Home-made Portafilter (PF) Gauge for under $25

    Accuracy? Well, prior to borrowing Vicroamers, I had measured the OPV using a real PF gauge and it measured 12 bar. Then I took vicroamers and it measured 12 bar on the dot. Adjusted the OPV so it read 9.5 bar. That was a few months ago. Measured it again yesterday using this one and it measured 9.8 bar. Dont know if its the accuracy or perhaps over time, the OPV might hve tighted up a notch, but its no cause for concern. It does a decent job for less than $25.
    BTW: 1 bar = 100 kPA

  4. #4
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    Re: Home-made Portafilter (PF) Gauge for under $25

    Nice one. Do you supply wholesale ;)

    charlie

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    Senior Member flynnaus's Avatar
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    Re: Home-made Portafilter (PF) Gauge for under $25

    Great idea. How deep is it from pf to gauge N2E?

    I guess the calibration needs to be considered. You already had something to measure against .


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    Re: Home-made Portafilter (PF) Gauge for under $25

    From the bottom of the PF to the bottom of the gauge is about 10cm. That sounds like there is enough space but you also have to add a bit more space because before you lock in the PF it is lower yet and then you raise it slightly to fit it onto the head and lock t in.

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Great idea! I was hunting some ideas on exactly this some time ago but something came up. I thought of a right-angle joiner to get around the depth problem of the gauge. Is your gauge fluid-filled? If not do you find it oscillates under load?

    Greg

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Doesnt oscillate at all. Its not liquid filled.

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Nice one NtoE ;)
    A cautionary note, water pressure gauges are generally not rated to espresso machine temperatures, just a matter of being on the safe side and checking pressure before water gets to hot.

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Quote Originally Posted by vicroamer link=1224889552/0#8 date=1224907286
    Nice one NtoE *;)
    A cautionary note, water pressure gauges are generally not rated to espresso machine temperatures, just a matter of being on the safe side and checking pressure before water gets to hot.
    Ah yes, I knew there was one other bit of instruction that you gave me when you lent me the gauge that I forgot to add in this thread. I remembered the plumbers tape bit and the not using the gauge face to tighten the connection bit.

  11. #11
    Senior Member flynnaus's Avatar
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    Re: Home-made Portafilter (PF) Gauge for under $25

    I know its the pump supplying the pressure but is there any significant difference in pressure at normal brewing temp?

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Quote Originally Posted by flynnaus link=1224889552/0#10 date=1224916477
    I know its the pump supplying the pressure but is there any significant difference in pressure at normal brewing temp?
    I think its more a case of damage done to the gauge from high temp water but the temp might affect how some of the components work too (heat expansion etc). In short... not sure so best measure at start up rather than after its gone hot for a few hours.

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    Re: Home-made Portafilter (PF) Gauge for under $25

    Good job NTE..... 8-)

    Now, if you want to get really finicky about this, what you need to do now is fit a suitable Needle Valve in between the gauge and the drain so that you can control the flow to equate to a normal espresso shot. This is the best way to set the OPV and removes the need to add a "fudge" factor to allow for the difference in pressure from a closed head to that with a 120ml/Sec flow.

    If you want to be really picky about it, ;)

    Mal.

  14. #14
    Senior Member flynnaus's Avatar
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    Re: Home-made Portafilter (PF) Gauge for under $25

    Quote Originally Posted by NewToEspresso link=1224889552/0#11 date=1224923690
    Quote Originally Posted by flynnaus link=1224889552/0#10 date=1224916477
    I know its the pump supplying the pressure but is there any significant difference in pressure at normal brewing temp?
    I think its more a case of damage done to the gauge from high temp water but the temp might affect how some of the components work too (heat expansion etc). In short... not sure so best measure at start up rather than after its gone hot for a few hours.
    Yeah I understood that but I meant that if you are then required to measure the pressure at lower than normal brew temp to protect the gauge, will the pressure reading be true at a lower temp?

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    Mal Dimal's Avatar
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    Re: Home-made Portafilter (PF) Gauge for under $25

    If you are referring to the OPV "flynnaus" this should be unaffected by the temperature of water in the Boiler, since the OPV is physically situated upstream from the Boiler and the water going through it is always cold.

    On the other hand, if you are referring to the Gauges accuracy as temperature is varied, then yes, there would be some variation but so long as you stay within the published operating parameters for the gauge you have, then the difference is of no real consequence. I guess if you wanted to find out exactly the differences you can expect, a message to the manufacturer may result in them supplying you with some application charts.

    Usually though, what is normally done where the medium being measured exceeds the temperature rating of the best gauge you can afford, is the fitting of an intermediate diaphragm installed between the gauge and the medium being measured and any intervening space filled with a suitable buffer liquid... Quite often a viscous silicone oil. None of this would really be required to set up the OPV in an espresso machine though.

    Cheers, :)
    Mal.

  16. #16
    Senior Member flynnaus's Avatar
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    Re: Home-made Portafilter (PF) Gauge for under $25

    Quote Originally Posted by Mal link=1224889552/0#14 date=1224940919
    On the other hand, if you are referring to the Gauges accuracy as temperature is varied, then yes, there would be some variation but so long as you stay within the published operating parameters for the gauge you have, then the difference is of no real consequence. I guess if you wanted to find out exactly the differences you can expect, a message to the manufacturer may result in them supplying you with some application charts.
    Yes that was I meant. So the difference isnt that critical

    Usually though, what is normally done where the medium being measured exceeds the temperature rating of the best gauge you can afford, is the fitting of an intermediate diaphragm installed between the gauge and the medium being measured and any intervening space filled with a suitable buffer liquid... Quite often a viscous silicone oil. None of this would really be required to set up the OPV in an espresso machine though.
    Thanks Mal. Thats what I wanted to know. Vicroamer/N2Es device is pretty much as good as a commercial unit but I imagine some sort of calibration would be advisable.

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    Re: Home-made Portafilter (PF) Gauge for under $25

    This might be a silly question, but what is the benefit of running your machine at 9.5 instead of 12bar?

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    Re: Home-made Portafilter (PF) Gauge for under $25

    cyrilgoldenrock wrote:
    This might be a silly question, but what is the benefit of running your machine at 9.5 instead of 12bar?
    Cyril, im far from experienced but in my case after spending weeks of absolute frustration with bitter shots due to blonding and seeing the gauge on my machine shooting up around the 12 bar mark i decided to act after getting some feedback from a fellow CSer :)

    i backed the pressure off till the gauge was reading around the 10.5 bar area and i havent looked back ;)
    ok, i will admit i still get the occasional channeling on some shots which is technique related but things have certainly settled down and a lot more consistent, but at least im actually using my machine again and its not sitting idle like it was when the pressure was set high but the best part about all this is the coffee is the best tasting coffee ive made so far :)

    Darren



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    Re: Home-made Portafilter (PF) Gauge for under $25

    Behmor Brazen - $249 - Free Freight
    Thanks Banjo.



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