I have a cereal crusher mill and have never used it before, any suggestions on a good gap setting to start off with?
Start with the stock gap and adjust from there. I set my MM2 to .35 recently and like my results.
I recently purchased a JSP Malt Mill with a pre-set gap of .040. First brew with it was a Kolsch (1.050 ish) and I got quick lautering and almost 80% efficiency. I was very pleased.
I, too, have the JSP Malt Mill and tighten it up just a 5 degree turn on both sides. I haven’t gapped it with a measuring device, but I am guessing it’s about .038 or so. I tried tighter and my cordless couldn’t turn the rollers well enough and my sparges got stuck, so I backed it off to that point eventually and now enjoy very good efficiencies and no stuck sparges.
Well there are a few things to consider when setting your gap.
First, what type of brewing to you do? Typical all grain / BIAB ??
Second, if typical all grain, do you use a false bottom, manifold, or SS braid?
That being said, IIRC the default gap is approx 0.50, and I wold start from there, you might fall into the if it aint broke don’t fix it category.
Before you crush anything, make sure you get a good gap measurement, and if you adjust, I would suggest dropping only 0.02 between batches.
Brew a batch, see what your efficiency numbers look like, also pay attention to your run off speed and how well your lautering goes.
If you BIAB or have a SS braid, you might be able to get away with starting in the 0.40 gap range.
In all cases, crush slow, it will keep the husk intact better.
I was once given some advice on how tight a spark plug should be when replacing it. My mentor said I should crank down on it until it breaks, than back off a tad. When I set my gap, I took it to below .030, and the hulls were too fine to allow a good lauter. I’m now at .032, and draining just fine.
I only do all grain, have a false bottom, and RIMMS system. I have feeler gauges, best thing I ever bought when I was 16, and set the gap on both sides to .040. Crushed some brown rice and was happy with the results. Maybe I will stop at my LHBS and get a pound of 2-row to test before brew day.
I don’t measure the gap, just played around with it until I got it right for me. I don’t find that every malt mills exactly the same so I’m likely to adjust it per batch anyway. I just grind a little, look at it, and adjust if necessary. When I do biab I go quite a bit finer than with my batch sparge set up which is a cylindrical cooler with false bottom.
This thread just reminded me that I haven’t set the gap on my barley crusher since I got it back after a rebuild. That would probably explain my efficiency drop. I had been getting .004 to .008 higher OG readings before the rebuild.
I usually run my mill around .038" and get good results (won’t quote %s since I never bother with the math).
Now to go find my feeler gauges. 
Paul
I am in the same boat as well, going to start at 0.45 I think and see what gives from there
.039 works very well for me.
I use a 0.88mm guitar pick to set my gap (which = 0.035"). It works great for BIAB.
that’s awesome multipurpose ingenuity there Eric.
I used my Costco card for the first day. I think that was .040
I play air guitar with the air from the gap between the rollers of my mill.
I’ve heard this before. Many homebrewers I know use a credit card to set the gap on their mills.
The best way to determine this IME is sieve testing.
I have the MM-3 and found that .035 is perfect for me. I run naked oats and wheat through it first when they are in the mill. I then dump them on the grain when I mill it. I found that I need to run it twice to get it all crushed. I could adjust for it, but twice is easier. I went to .030 and stuck city. I use a cooler with a copper manifold.
I bought some feeler gauges, but they were covered in oil of unknown origin. I wasn’t too keen on sticking that in my mill, so I did the math and went digging through my pick stash. It’s a Dunlop Tortex green, for anyone interested.
I use Tortex 1.0mm guitar picks. One millimeter is in between 0.039" and 0.040".