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Thread: Grain Mill Roller Speed

  1. #1
    Join Date
    Nov 2007
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    34

    Grain Mill Roller Speed

    I don't know if it matters much, as the manufactures of every mill spec their own out individually, but what should the typical speed of the rollers be on an average mill? We were thinking in the 250 RPM range? Is this way off or in the realm?

  2. #2
    Join Date
    Jan 2009
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    44

    http://probrewer.com/vbulletin/showthread.php?t=13818&highlight=mill+crush


  3. #3
    Join Date
    Nov 2007
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    34

    Thanks

    That helps for when we get it going, but right now we are looking at sheaves tying to figure out our ratio. This is for the Micro Brewery Mill that BC Entr. makes. Anyone else with an idea of an acceptable speed? We are a small brewery looking at 120-200# of grain.

  4. #4
    Join Date
    Oct 2007
    Posts
    9
    we are looking at sheaves tying to figure out our ratio.
    Get a gear motor and you can build a nice looking mill.
    For my toy mill I used a Bodine gear motor and run the mill at 94 RPM, 3 lbs a minute with 1-1/2" rollers.
    The Barley Crusher mill design might limit your speed to below 500 RPM.
    Call BC and ask for specs.

    Cheers,
    ClaudiusB
    My setup:http://photobucket.com/ClaudiusB

  5. #5
    Join Date
    Nov 2007
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    34
    I believe the one your talking about is the home brew version. I have that one from times past. We are looking at the Micro series that BC makes. I was hoping for the neighborhood of 10-20# a min. I think a smaller complete mill from Apollo or Robix might be a better choice for us.

  6. #6
    Join Date
    Oct 2007
    Posts
    9
    The BC Micro Brew series crushes 20 lb/min but requires two motors as per BC specs.
    Each roller is driven by one motor.


    Cheers,
    ClaudiusB
    My setup:http://photobucket.com/ClaudiusB

  7. #7
    Join Date
    Jan 2003
    Location
    Palau
    Posts
    1,611
    Gabe, your answer is in the link that BigMuddy sent you. RPM is NOT the deciding factor, periphery speed is.
    "Rolls should run at 2.5 - 4.0 m/s on the periphery. "
    I'd be wary of tiny rolls, too. They produce an inferior crush. A few percentage points on yeild will add up over a few years. Good luck!
    Phillip Kelm--Palau Brewing Company Manager--
    Worldwide Brewery Installations
    www.GitcheGumeeBreweryServices.com

  8. #8
    Join Date
    Jul 2011
    Posts
    18
    Quote Originally Posted by gitchegumee
    Gabe, your answer is in the link that BigMuddy sent you. RPM is NOT the deciding factor, periphery speed is.
    "Rolls should run at 2.5 - 4.0 m/s on the periphery. "
    I'd be wary of tiny rolls, too. They produce an inferior crush. A few percentage points on yeild will add up over a few years. Good luck!
    I am assuming you mean 2.5m/s is the tangential velocity on the roller. For a smaller mill with 2" rollers like many micros have you would need an RPM of 6000 to achieve that at the roller not at the motor.

    v = 2.5m/s = rw = 0.0254(m) x w(rev/s)

    w = 98.4 rev/s = 5905 rpm

    For a 6 in roller...

    2.5m/s = rw = 0.0762(m) x w (rev/s)

    w = 32.8 rev/s = 1968.5 rpm

    I guarantee no brewery is running their mill at 6000rpm or 2000rpm. You would shred the grains. Unless I am making a bad assumption, that rule doesn't work. RPM would be a better data point to look at or those speeds are wrong. Are you sure it wasn't 2.5 - 4 in/s? That works better.

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