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Old 05-12-2008, 10:23 PM   #1
olllllo's Avatar
Apr 2006
Phoenix, Arizona
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I recently came across this in BYO"

A common drill motor can motorize most mills. The problem with this approach is, while it works, it simply works too fast. Optimum roller speed for small homebrew mills is 150–200 rpm. Drills and most AC motors run at 1,750 rpm (U.S. 60 cycle AC.) The answer is to use pulleys and belts or an expensive gear reduction motor to run your mill more slowly.

My only remedy right now is to use the torque setting on my drill and reduce the trigger.

Might explain a few points of efficiency and some individual differences between brewers with identical settings on the same mill.
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Old 05-12-2008, 10:26 PM   #2
Soulive's Avatar
Mar 2007
The Middle of NJ
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Originally Posted by olllllo View Post
My only remedy right now is to use the torque setting on my drill and reduce the trigger.
Same here. I have been wondering about this in the past and the BYO mention supports my suspicion. I'll ease up on my RPMs and see what happens. Then again, Bobby_M crushes fast and has no problems...

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Old 05-12-2008, 10:29 PM   #3
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Aug 2006
Whitehouse Station, NJ
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The article doesn't really say why faster is bad. My dewalt's low speed is 300rpm unloaded so I'd imagine it bogs to abotu 250 during the crush. I suppose I could slow it down by half triggering it but ehhh..
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Old 05-12-2008, 10:35 PM   #4
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Mar 2006
Sierra Vista, AZ
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I dont see how it changes the crush, or is it bad for the mill?

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Old 05-12-2008, 11:13 PM   #5
John Beere
Deep Six Brewing Co.
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May 2006
Valdosta, GA
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I just bought a new mill (see here: after ruining my old JSP with my handheld drill... didn't know it until after powder-izing 18 lbs of grain. Doh!

Anywho, I just bought a 12" sheave and a 1.5" sheave along with a 48" 4L belt to reduce the 1/2 HP 1725 RPM motor down to ~ 200 RPM. Hopefully gonna build my milling station next weekend...

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Old 05-12-2008, 11:14 PM   #6
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Nov 2006
Central PA
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Well, I hand crank so.....
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Old 05-12-2008, 11:44 PM   #7
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May 2006
Adams, MA
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I hit 90% last time running basically full-bore.

The only thing that would make sense to me is if a fast crush is shredding the husks too much for them to form an effective filter bed, but it seems the downside would be difficulty in sparging, not an efficiency reduction. That, or maybe excessive tannin extraction. All theoretical, though; I know Bobby's spoken at great length about NOT having those issues with his high-efficiency mash, and I haven't noticed anything myself.
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Old 05-13-2008, 12:16 AM   #8
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Jun 2007
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I've wondered about this, too. I've a Barley Crusher on which I use an old electric drill that is difficult to control the speed with the trigger. It's generally too fast. I'm going to try slowing it down next time by using my Rigid battery-powered drill, but FWIW I've always got about 92% efficiency, both from grain crushed at the LHBS and the Barley Crusher with my too-fast drill.

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Old 05-13-2008, 12:25 AM   #9
May 2007
Cary, NC
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My 5-year old is in charge of running the Barley Crusher, and he likes to use the corded DeWalt drill. I'll read him this article from BYO and see what he thinks. Chances are, it won't change his mind any.


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Old 05-13-2008, 12:31 AM   #10
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Jan 2006
Santa Cruz, CA.
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Originally Posted by zoebisch01 View Post
Well, I hand crank so.....
Yeah me too. About a 100 RPM's is my guess.

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