.025 Gap vs. Double Milling

[Jordan Logo]

Question: What is the actual difference between the two? I don't really have the room for my own grain mill, but I have access to double milling from my LHBS.

 

[FatDragon]

A narrow gap creates a lot of small pieces and almost no big ones. A wider gap makes a lot of medium pieces and lets a moderate amount of big ones (i.e. whole or nearly whole grains) through. Double crushing allows a lot of the smaller and even many of the medium pieces through on the second pass, but most of the big pieces that contribute to low efficiency will be caught. Thus, the pieces in double-crushed grain should be a bit bigger on average than those run through a narrow gap once, meaning it'll take a bit longer to convert (but generally be well done within the 60 minute timeframe of most mashes) and you might lose a couple points on efficiency, but it'll drain faster. Single-crushed narrow gap grain will be smaller and include more flour and shredded hulls, so faster conversion, probably slightly higher efficiency, but longer bag draining times.

 

[myndflyte]

I'm assuming you're doing BIAB? If you are able to adjust the gap at your LHBS, I'd get it as small as possible and do a double crush.

 

[cswant88]

In my opinion, double crushing is pointless unless you adjust the gap down for the 2nd crush. If they didn't get crushed the first time through, I think it unlikely they will get crushed the 2nd time through. I own my own mill and just keep it set to the narrowest gap it will allow for MIAB.

I admit, I have never attempted a double crush, so for all I know it could work great.

 

[LittleRiver]

...I don't really have the room for my own grain mill, but I have access to double milling from my LHBS.

I saw a definite jump in my conversion efficiency when I started milling my own grains. If you're going to BIAB, make getting your own mill a priority.

I don't get the comment that you don't have the room for it. Your mill can mount on top of a 5gal bucket, which can be stored inside your kettle (in most situations).

 

[IslandLizard]

What @FatDragon said. ^

In short, milling once at the correct gap (for your system) is always better and preferred to milling twice or thrice on a gap that's too wide. In the latter case the result is mediocre at best. Especially when you have small kernel grain included, like wheat, rye, etc.

I think it was mentioned in a previous thread, a $25 knock-off Corona corn mill can give you excellent milled grist for BIAB or even conventional mash, better than most LHBS mill.

To make up for lower efficiency due to a grist that's (too) coarse, just add a few extra pounds of base malt and/or mash 30' longer.

 

[HB2 HughBHomeBrew]

I saw a definite jump in my conversion efficiency when I started milling my own grains. If you're going to BIAB, make getting your own mill a priority.
...

Agree. I just got my own mill (Monster Mill), re-milled some "double milled" grain that I had ordered online (no LHBS option where I live). I re-milled it at .020 gap on the Monster Mill and first batch that way I had big improvement in yield/efficiency. 90% "Brewhouse efficiency" on my first test like this vs about 65% in previous batches from same grain source - double-milled.

 

[IslandLizard]

Agree. I just got my own mill (Monster Mill), re-milled some "double milled" grain that I had ordered online (no LHBS option where I live). I re-milled it at .020 gap on the Monster Mill and first batch that way I had big improvement in yield/efficiency. 90% "Brewhouse efficiency" on my first test like this vs about 65% in previous batches from same grain source - double-milled.

Wow, almost 50% more extraction. That's a remarkable improvement!

@Jordan Logo, good stirring of the mash, especially during doughing in, should help improving efficiency with coarser grists. A good stir once or twice during the mash adds to that, alas, you may suffer a few degree temp drop due to opening the lid. This brings up another point. How well do you maintain the mash temp during that hour? Do you wrap and cover the kettle with something, like a blanket or sleeping bag, to keep the heat in?

Have you determined your actual mash/brewhouse efficiency?

 

[RM-MN]

I don't really have the room for my own grain mill,

I think it was mentioned in a previous thread, a $25 knock-off Corona corn mill can give you excellent milled grist for BIAB or even conventional mash, better than most LHBS mill.

I have one of those cheap knock-off Corona corn mills and get excellent efficiency from using it. Taken apart for storage if only requires about 6" by 6" by 16" so you would have to be really cramped to not have room for one.

 

[Soulshine2]

Question: What is the actual difference between the two? I don't really have the room for my own grain mill, but I have access to double milling from my LHBS.

I mill at 0.030 , twice.

 

[OG-wan Kenobi]

With BIAB you want the finest crush you can get. I use the finest crush my mill will give me and toss in a hand full of rice hulls to speed up the bag drain, not sure how much of a difference it makes but that's what I do and I get excellent results

 

[Soulshine2]

Mills dont take up much space. How can you not have one, mine sits atop a 5 gallon bucket lid . I use a cordless drill driver to run it.
Someone in here had built themself a brew station and incorporated a swing out or drawer slide out milling station that I may adopt myself. Its all about convenience and control of your brewing.

 

[Kenmoron]

I don't own a mill and just run the grain through the mill at my LHBS twice. My mash efficiency is pretty consistent at 76-78%. I'm pretty satisfied with it for now.