While the gauge is not accurate in absolute terms, it is accurate in
relative terms.  You can set it at 9 today and it will read 9 tomorrow. So
it does give you a simple way to adjust pressure up or down a known amount,
even though you may not know the exact pressure you wind up with.  You may
start at 9 on the gauge, 8 actual, and increase by 1 bar.  Then you'd have
10 on the gauge, 9 actual.  You'll have to tweak until you find what you
like, then can leave it alone--not something that you need to worry about
very much unless it's waaaaay off.
bmc
"Faith will move mountains, but you'd better bring a shovel....."



> From: shixx <[email protected]>
> Reply-To: <[email protected]>
> Date: Mon, 16 Feb 2009 03:48:46 -0800 (PST)
> To: Brewtus <[email protected]>
> Subject: Re: Adjusting pressure
> 
> 
> yes, the guage is mostly for decorative and entertainment  purposes.
> 
> 
> 
> On Jan 28, 11:58 pm, Chris Bailey <[email protected]> wrote:
>> Ok, read that thread.  I guess what's strange to me is that, the gauge is
>> almost pointless.  I suppose it's useful to know if something has gone
>> really wrong, but otherwise you can't really use it to adjust or to fine
>> tune your pressure.  It's just a little misleading to me I guess.
>> 
>> 
>> 
>> On Wed, Jan 28, 2009 at 8:03 PM, TWG <[email protected]> wrote:
>> 
>>> Search this group with the terms:  Calibrating Brew Pressure
>> 
>>> This should help clarify the difference between the pressure shown on
>>> the Brewtus guage versus the pressure in the portafilter.  11.5 on the
>>> Brewtus guage may be a bit high but not way out of line.
>> 
>>> On Jan 28, 10:36 pm, Chris Bailey <[email protected]> wrote:
>>>> Just confirmed, with a blind PF in, it holds steady at 11.5 bar on my
>>> gauge.
>> 
>>>> On Wed, Jan 28, 2009 at 7:33 PM, Chris Bailey <[email protected]
>>>> wrote:
>> 
>>>>> This was one of my worries, was that the pressure gauge wasn't
>>> accurate,
>>>>> and then as per Todd's note that what the gauge reads isn't necessarily
>>> what
>>>>> the actual pressure is.  That is pretty poor in my opinion - why bother
>>>>> putting a gauge on there if it's going to be wrong.  But, alas, that's
>>> what
>>>>> we have.  This is one reason I'm nervous to monkey with it, as it's
>>> hard to
>>>>> say whether it's really wrong or not, it just surprised me that mine
>>>>> consistently reads 11 bar (with blind PF or when pulling shots).  I'll
>>>>> verify that in a few minutes, but pretty sure.
>>>>> I'm grinding, tamping, etc. as per standards AFAIK: 30lb tamp, grounds
>>>>> typically around 15g in the double basket, grind setting such that my
>>> shots
>>>>> are typically in the 25-30 second range from the time I pull the lever
>>> to
>>>>> when I've filled a cup approx 1.5oz by volume (I mostly pull shots by
>>> where
>>>>> it fills to on my cups, but have measured this and it's right about
>>> 1.5oz).
>>>>>  I've read a fair bit, practiced a ton, use only fresh beans (3 to
>>> maybe at
>>>>> most 9 days after roast date), grind on a nice Macap grinder, etc.
>>>  I've had
>>>>> a friend who's pulled a ton of shots use my machine as well.
>> 
>>>>> On Wed, Jan 28, 2009 at 7:05 PM, <[email protected]> wrote:
>> 
>>>>>>  Also be aware that the pressure gauge on the Brewtus II can be wrong.
>>> I
>>>>>> went to considerable effort and expense to more or less establish (to
>>> the
>>>>>> degree that the large pressure gauge that I bought is accurate. It was
>>> sold
>>>>>> with the statement that it has an accuracy of 1%) that the pressure
>>> gauge on
>>>>>> my machine is two bar off. I wrote about this at the time on this
>>> group, so
>>>>>> you might be able to find it with a search.
>> 
>>>>>> Allen
>> 
>>>>>>  *From:* Chris Bailey <[email protected]>
>>>>>> *Sent:* Wednesday, January 28, 2009 4:56 PM
>>>>>> *To:* [email protected]
>>>>>> *Subject:* Re: Adjusting pressure
>> 
>>>>>> My screw looks like it's metal, and is located on the front of the
>>>>>> machine, lower right corner, once you've removed the drip tray.  Sound
>>>>>> right?  I do tamp to 30lbs.  I'll use the blind PF to set the
>>> pressure,
>>>>>> thanks for that info!
>> 
>>>>>> On Wed, Jan 28, 2009 at 5:46 PM, BinBakinBeans <
>>> [email protected]>wrote:
>> 
>>>>>>> Which version of Brewtus?
>>>>>>> The first had a teflon screw on the opv valve that became problematic
>>>>>>> after adjusting the pressure.
>>>>>>> The first of the BII had teflon as well. They were later switched to
>>>>>>> an opv with a brass adjusting screw. I replaced mine with one of
>>> these
>>>>>>> after I had problems with my original teflon screw opv on my BII.
>>>>>>>  Strangely enough, Expobar has again gone back to using an opv with a
>>>>>>> teflon screw on the new BIII machines.
>>>>>>>  I would say go ahead and adjust it, especially if it is a brass
>>>>>>> screw. If it is teflon, be prepared to "possibly" have some future
>>>>>>> problems with it. Not a big deal to change it out if you do.
>>>>>>> Use the blind filter in the portafilter to get it down to about 8.5
>>> to
>>>>>>> 9 on the guage.
>>>>>>> Check again when you actually pull a shot that it is around 8.5. I
>>>>>>> will assume that you will have properly tamped to about 30 pounds.
>> 
>>>>>>> On Jan 25, 12:27 pm, Chris Bailey <[email protected]> wrote:
>>>>>>>> I've seen a fair bit of talk on the list about adjusting pressure.
>>>>>>>  Given
>>>>>>>> the fact that there's tape over the pressure adjust screw on my
>>>>>>> machine, and
>>>>>>>> all the warnings about don't touch it, only let the factory do it,
>>> etc,
>>>>>>>> etc., I'm leery of messing with it.  Also, my understanding is that
>>>>>>>> supposedly the factory has pulled shots and checked the pressure
>>> and
>>>>>>> set it
>>>>>>>> properly.
>>>>>>>> But, I've just wondered about it.  My pressure gauge typically
>>> reads
>>>>>>> about
>>>>>>>> 11 bar when I'm pulling shots.  I'm unclear on whether it's
>>> supposed to
>>>>>>> read
>>>>>>>> the true 8.5-9 bar that an espresso should be done at, or whether
>>> the
>>>>>>> gauge
>>>>>>>> is a pressure at a different point in the system and thus the real
>>>>>>> pressure
>>>>>>>> at the PF is lower, or not.
>> 
>>>>>>>> Can folks discuss this a bit?  Other than taste, are there ways for
>>> me
>>>>>>> to
>>>>>>>> know whether my machine is set right or not, and/or if I'm going to
>>>>>>> adjust
>>>>>>>> it (and potentially void my warranty?) how can I know when I've set
>>> it
>>>>>>> to
>>>>>>>> the right spot?  From the reading I've done I think I understand
>>> that
>>>>>>> too
>>>>>>>> much pressure can actually cause a build up and not get things
>>> flowing
>>>>>>>> properly (which seems a bit backwards, but I sort of understand).
>> 
>>>>>>>> Anyway, let me know what folks think.
>> 
>>>>>>>> --
>>>>>>>> Chris Bailey
>>>>>>>> [email protected]
>> 
>>>>>> --
>>>>>> Chris Bailey
>>>>>> [email protected]
>> 
>>>>> --
>>>>> Chris Bailey
>>>>> [email protected]
>> 
>>>> --
>>>> Chris Bailey
>>>> [email protected] Hide quoted text -
>> 
>>>> - Show quoted text -
>> 
>> --
>> Chris Bailey
>> [email protected]
> 
> > 



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