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Thread: Filter basket conversion to unpressurised advice required?

  1. #1
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    Filter basket conversion to unpressurised advice required?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Many of the postings I have come across, advising on conversions from pressurised to unpressurised functionality, suggest radical metal removal from the baskets lower skin.
    I have enlarged the exit hole in the double shot pressurised filter basket (Breville Cafe Roma) using a pistol drill, was very easy.
    How big does the exit hole need to be, for appropriate non-pressurised function etc?
    Can anyone offer sound guidance either evidence based or theoretical as to a satisfactory size range for this exit hole?

  2. #2
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    Re: Filter basket conversion to unpressurised advice required?

    I drilled out all of the indentations under the cafe roma basket on mine. This left me with approx a 1cm square perforated section.

    I think i used a .8mm drill bit

    One hole did not reduce pressure by much.

    Try blowing air through it - you will see what I mean.

  3. #3
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    Re: Filter basket conversion to unpressurised advice required?

    Somehow I finished up with the same question posed in 2 spots, PL and Mokka responded with A1 advice, thanks Guys.

    Quote Originally Posted by 69505A5A56555675584D4D5C390 link=1241958773/1#1 date=1242001991
    I drilled out all of the indentations under the cafe roma basket on mine.This left me with approx a 1cm square perforated section.
    I think i used a .8mm drill bit
    One hole did not reduce pressure by much.
    Try blowing air through it - you will see what I mean. *
    Quote Originally Posted by 32282C2E2F2C242D23410 link=1197963857/34#34 date=1242014264
    Or if you are very careful and the basket and lower (pressuirised section) will not separate, then you can simply drill a hole (about 5-8mm bitt) through the small pressurised hole. This is what I did with a Brevile Cafe Roma basket. Just be careful not to drill all the way through the filter!
    Cheers
    Simon
    The first enlargement of the exit hole (previously drilled) was too easy so I thought just enlarge it to about 7mm would be quick and easy (exit hole/s with a similar cross sectional area to the sum of the filter holes seemed reasonable).
    Well not quite so, but eventually finished with a satisfactory result.
    The main difficulty was that drilling the very thin unsupported metal caused it to deform readily away from the cutting edge of the drill bit.
    If I did it again, I think Id drill multiple fine holes.
    Thanks Mokka and PL
    Kind Regards
    Lindsay

  4. #4
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    Re: Filter basket conversion to unpressurised advice required?

    Yeah. You need a really sharp bit to drill stainless (or any metal when its that thin really) otherwise you just deform it like you found out.

    I had the slight advantage of utilising a drill press. But even so, I still made a few dents in the filter - they didnt go through it though.



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