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Thread: Izzo Alex Leva

  1. #551
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    The 'correct' number isn't all that important and not really possible. It depends on a lot of factors..like the accuracy of the pressure gauge (likely not precision/lab grade), calibration of the temp probe (similar story to the gauge, likely not calibrated), PID offset and sea level. In the end, as long as it's reading consistently that's all you need.

    For the expected number (based on physics), you can check this out:
    http://www.tlv.com/global/TI/calcula...mperature.html

    For instance, at 120C it should be 1.986 bar (absolute) minus your atmospheric pressure = roughly 0.97 bar (on gauge).
    Dimal, Paolo, kbc and 1 others like this.

  2. #552
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    Hi,
    I have no idea what my pressure gauge says. I doesn't affect how i make coffee. I just adjust the temp up or down depending on type of beans and then alter according to taste
    Cheers
    Dave
    Dimal and RichardC like this.

  3. #553
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    Quote Originally Posted by samuellaw178 View Post
    The 'correct' number isn't all that important and not really possible. It depends on a lot of factors..like the accuracy of the pressure gauge (likely not precision/lab grade), calibration of the temp probe (similar story to the gauge, likely not calibrated), PID offset and sea level. In the end, as long as it's reading consistently that's all you need.

    For the expected number (based on physics), you can check this out:
    Calculator: Saturated Steam Table by Temperature | TLV - A Steam Specialist Company (International)

    For instance, at 120C it should be 1.986 bar (absolute) minus your atmospheric pressure = roughly 0.97 bar (on gauge).
    Great stuff Samual, I'm glad there are folks like you out there that are all over this stuff, it does my head in frankly.

    I simply look at a guide and make sure I'm close enough to it but my baby may be a little further away from optimum with a 0.15 (120 @ 0.85) difference, are you saying it's not enough to worry about as it's consistently read the same which it does?

    I just compare that difference to a timing chain on the engine of a car, if the time is out, it's out and the engine is sluggish with obvious results. And being the perfectionist that I try to be I'm just wondering if I'm missing out on the optimum pour.

  4. #554
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    Quote Originally Posted by Dr_Dave View Post
    Hi,
    I have no idea what my pressure gauge says. I doesn't affect how i make coffee. I just adjust the temp up or down depending on type of beans and then alter according to taste
    Cheers
    Dave
    Totally agree.

    It's the "but what if" that playing on my mind.

    What if the bar was at optimum level and at your preferred temp, and improves taste?

    Maybe I'm drawing an "unscientific" long bow.......always on the quest for improving status quo

  5. #555
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    Quote Originally Posted by RichardC View Post
    Great stuff Samual, I'm glad there are folks like you out there that are all over this stuff, it does my head in frankly.

    I simply look at a guide and make sure I'm close enough to it but my baby may be a little further away from optimum with a 0.15 (120 @ 0.85) difference, are you saying it's not enough to worry about as it's consistently read the same which it does?

    I just compare that difference to a timing chain on the engine of a car, if the time is out, it's out and the engine is sluggish with obvious results. And being the perfectionist that I try to be I'm just wondering if I'm missing out on the optimum pour.
    Glad it helps Richard. Rest assured your machine is fine. Any discrepancy will come from either (i) gauge measurement error (ii) temp probe measurement error (iii) temp probe placement error. It's a measurement error and not a performance indicator.

    As DrDave has said, just adjust the temp based on taste. Your real 'optimal' pressure/temp will likely be the same as another Snob (if you guys are using same bean same roast etc with the same taste preference) even if your gauges don't read the same.
    RichardC likes this.

  6. #556
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    Got it Samual, thanks again for breaking it down for me

  7. #557
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    Quote Originally Posted by AlMac View Post
    If anyone can find the tool needed to take the cap of the piston let me know. I am starting to think it doesn't even exist, except at the factory where they are put together.
    I found it - it's called a Budd Nut Socket.
    Now trying to buy one in the right size with the correct size pins and configuration.
    Have to take the piston in to a specialist tool shop.

    Got lucky. A tool guru looked at my photo of it and knew what it was.

  8. #558
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    Thanks Al,
    I'd appreciate you letting me know when you find it as I would buy one also
    Cheers
    Dave

  9. #559
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    I was going to a tool shop to have one manufactured. But, if there is one somewhere, I would like to buy one too.

  10. #560
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    Quote Originally Posted by Hack View Post
    I was going to a tool shop to have one manufactured. But, if there is one somewhere, I would like to buy one too.
    Will let you know how I get on.
    Should get a chance to take the piston out of the machine and into the tool shop in the next couple of days.
    Dr_Dave likes this.

  11. #561
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    Quote Originally Posted by AlMac View Post
    Will let you know how I get on.
    Should get a chance to take the piston out of the machine and into the tool shop in the next couple of days.
    Another dead end.
    The smallest diameter the tool shop could get in was bigger than the piston diameter.

    I did learn that the four small notches in the piston head are 6mm across.

    While a pin spanner will work well when the piston is out of the Lever Group Body, it won't help you reassemble the piston inside the Lever Group Body.
    This is important because when you put in a new gasket you cant slide it back down from the top of the Lever Group Body - it flares out from top to bottom.

    I ended up using two 6mm allen key heads, inserted them into two of the buds, placed a large screwdriver horizontally between them, held it all together with my hands and screwed the piston head down until it was below the shower screen line.
    Not ideal. Not keen to repeat it.

    To work on the group I think you need, as a minimum:
    1. wrench and allen key to remove the bolts holding the Lever Group Body together;
    2. wrench to remove the bolts holding the Lever Group Body onto the main body;
    3. 90 degree bent nose pliers to remove shower screen C/lock ring. Don't skimp. Get the right size nose on your pliers. This lock ring takes some serious pressure to remove;
    4. Vice to hold the Lever Group Body while working on it and a thick rag to protect your beautiful chrome surfaces;
    5. some kind of tool to take the piston head off and then get it back on when installed back into the Lever Group Body;
    6. rubber mallet to very very gently tap the parts of the piston back into the Lever Group Body - patience and super care to line things up and gently get them in is the key;
    7. Molykote 111 lubricant. A think smear is all that is needed on the gasket and silicon O-ring (if you like). Do not overgrease - excess grease will end up coating the edges of the shower screen.

    Ultimately, it is beautifully simple. Unfortunately, the vital part required to take the piston head off is not readily available.

    Note - the springs are not held on by the piston head. There is a separate large bolt holding them in position which sits underneath the piston - which is exposed once the piston is removed.

  12. #562
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    So, with the right tool, my understanding is that you can service the group head after screwing the piston out from underneath without disassembling the whole lot and removing it from the main body.
    Just out of curiosity, has anyone tried to contact the manufacturer in Italy?
    Even the people at Jetblack said that to service this machine they would either remove the top assembly or manufacture their own tool.

  13. #563
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    Hi All,
    Some information here
    http://www.home-barista.com/levers/i...t25094-40.html

    I haven't made a tool out of pvc as was hoping to purchase one. If anyone finds one, lots of us would be keen to know where from
    Cheers
    Dave
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  14. #564
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    Quote Originally Posted by Hack View Post
    So, with the right tool, my understanding is that you can service the group head after screwing the piston out from underneath without disassembling the whole lot and removing it from the main body.
    Yes you probably can.
    I haven't tried that.
    I think the shower screen would be hard to get out and in upside down.

    Quote Originally Posted by Hack View Post
    Even the people at Jetblack said that to service this machine they would either remove the top assembly or manufacture their own tool.
    Does that mean Jetblack hasn't serviced one?

    I wonder if anyone has.

    Tool wouldn't need to be super strong - there's not a huge amount of pressure on the piston head when screwed in.

  15. #565
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    Quote Originally Posted by Hack View Post
    Just out of curiosity, has anyone tried to contact the manufacturer in Italy?
    Gave that a try.
    Answer - couldn't help.

  16. #566
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    Just trying to understand here (have not seen a disassembled LSM group in person)...is it necessary to unscrew the piston for servicing? Can't we just remove the lever/piston assembly from the top, and stretch the gasket over the piston (I am assuming we're trying to replace the piston seal here)?

  17. #567
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    Quote Originally Posted by samuellaw178 View Post
    Just trying to understand here (have not seen a disassembled LSM group in person)...is it necessary to unscrew the piston for servicing? Can't we just remove the lever/piston assembly from the top, and stretch the gasket over the piston (I am assuming we're trying to replace the piston seal here)?
    No. Two reasons.

    1: the gasket will not stretch over the piston. It is not that flexible and it sits partly inside the piston itself. It isn't a simple ring like the gasket at the group head.

    2: once a new gasket is an installed it will not go back in from the top. It is too wide when new.
    samuellaw178 likes this.

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