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Grain crush gap setting info

MaltLicker

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I was curious about the grain mill gap setting and figured I'd ask the major online HBS that crush a lot of grain.  They would know, right?  And they'd likely attempt to crush grains well-enough to deliver a good mash without answering lots of complaints about stuck sparges.  Below are seven responses from all the big retailers that you know by name.  The two interesting notes, IMO, were the wide range from 0.025 to 0.040/45, and two, the company that crushes different grains differently.  My takeaway is that there is room to experiment and likely crush finer. 


We have our grain mill set at .025. Hope this helps!

We generally keep the mill around 0.040 give or take 0.005 depending on the type of grain that's being milled.

....we use an industrial mill to crush our grains, which of course makes sense due to our high volumes.  However, because of this, I do not know what the measurement for the roller spacing is on the mill.  The settings have 1 to 5, 1 being the coarsest setting, 5 being the finest.  We did recently change the setting from a 3 to a 4 due to requests from our customers for a finer crush.

Our mill doesn't have any calibrated setting numbers. We just keep an eye on the grain to make sure it looks the way it should from experience.

We never specify a "magic gap."  All grain is different and its crush should be evaluated individually.  Further, the danger of a stuck mash from crush consistency is wildly overstated.  I look at the grist and check to see that I can’t easily find whole corns that will give you nothing.  On the other hand, you should be able to find some whole corns because some are undersized.  If you can’t find them, you are likely too tight.  As Denny Conn says, "crush it until you get scared."  This is good advice.

Here are the general settings that we use on our mill:

    * Dark Grains:    0.50
    * Most Grains:    0.35
    * Maris Otter:    0.30
    * German Pils:    0.30
    * Wheat, Rye:    0.25


I feel 1.036-1.039 is perfect. I hear people say that they get better efficiency with a finer crush, but do not believe them. A friend that I brew with would tell me the same. I brewed with him for the day and we tested the end results. He was right, his had a higher gravity, initially. He gave me the old "I told you so". My sample was clear and free of particles (From a proper grain bed) his was cloudy and full of grains. We waited an hour and his settled out. At that time, my sample was 2 points higher. He was shocked! The grain in his reading was giving a false wort reading because of his fine crush.  He now uses a 1.037 on the mill.
 

Wildrover

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Interesting post!!

I know my setting is pretty tight and my efficiency is pretty high with no off flavors due to tannin extraction.  I say squeeze em in.
 

Wastegate

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Interesting insight into what others think. I have left mine at the factory setting, however I have been thinking of changing it.

Cheers
Preston
 

MaltLicker

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I tightened to 1.032 today on an inventory-clearance hodge-podge of MO, 2-row, and Beligan Pilsner and the kernels were clearly smaller, while the husks did not look to be much more degraded than they were at 1.037.  Lautering was fine. 

Amazingly, turning the crank seemed easier.  And for the third time I found a small gray rock in the MO.  Definitely going to start scanning more closely for rocks the night before. 
 

Wildrover

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MaltLicker said:
I tightened to 1.032 today on an inventory-clearance hodge-podge of MO, 2-row, and Beligan Pilsner and the kernels were clearly smaller, while the husks did not look to be much more degraded than they were at 1.037.  Lautering was fine. 

Amazingly, turning the crank seemed easier.  And for the third time I found a small gray rock in the MO.  Definitely going to start scanning more closely for rocks the night before. 

Any change in efficiency?
 

MaltLicker

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I also changed some water volumes as I dial in the system, so it's obscured, but yea, I hit the pre-boil dead on for the first time on the new system, using the same EE% in the recipe.
 
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