it’s been said before - if you’re lacking a feeler gages, use hotel room cards or whatever, but something thinner than a credit card.
For me, getting the gap setting right is the key. Double crushing grain has not resulted in notable increased efficiency, nor crazy lautering. Maybe I’m missing something, but that’s what lands its with the setup I have.
Here’s the thing - you’re getting a good crush from the get go . But alot of LHBS are notorious for crushing just enough “to give good results and not cause a stuck runoff”. But in reality the LHBS wants you to accomplish that but, in the process, maybe have to buy an extra lb or two of grain, hoping you assume that that is the efficiency you can achieve with a given grist. I got the big jump in efficiency because I worked on correcting everything else first, and then realized belatedly that a finer crush might help ( been brewing since good info was more scarce).
Hot tip - I use a 0.88mm guitar pick, which is roughly a 0.035" gap. You can pick a couple up at someplace like guitar center on the cheap.
Pro tip: I’ve never measured the gap. I just adjust it til I get a good crush, then leave it alone!
Denny is his own feeler gage. I like that method. Go by what it looks like, maybe a small adjustment here and there depending on the grain
You’re making grist, not gaps. All I care about is the grist. FWIW, I set the gap on my mill over 10 years ago, and it never changes no matter what grain I’m using.
I use a Victory “corona” type mill. I adjusted it two or three times early on. The only other time I change it is for Maris Otter because it gets too powdery and too many dough balls if I don’t. With a corona adjustments are easy though. I don’t think a roller would have that problem with MO, probably.
It’s both grist and gap - I made my crusher and can quickly rebuild/tune it, but I need a reference point. I like the DIY hacking aspect. Less $$$, more learning. I still need to try Ph adjustments (the next “step up”), but for me the gap and crush quality is the most obvious factor in efficiency.
Obviously you and others have more experience than I, but it’s what I’m observing in efficiency.
Technically I grind not crush. Early on I noticed an efficiency increase by tightening my grinder gap a bit. The next big increase came when I quit doing mid mash stirs. Denny suggested stirring at mashin and then leaving it alone. Helped a bunch. But my current efficiency is about 75-78%. Not record setting, but good enough for me. More importantly it’s stable and predictable.
+1 - I don’t want to adjust the mill setting (using a Schmidling Malt Mill), so for me a double crush at his factory setting doesn’t result in a stuck sparge, but gets my efficiency up in the high 70’s to 80’s, without fiddling with the setting or adding rice hulls. The grist looks right and I don’t mind the time for a second pass while my sparge water gets to temp.
I’ve had the same problem before. Crush was the first culprit. I run a two-vessel system and after a traditional mash I do a full volume, continuously recirculating sparge and recirc until I hit my numbers. With a bad crush I’ve had that take as long a 3.5 hours! Double crushing at the LHBS is the easiest fix.
I also discovered that my thermometer was off, so when I thought I was mashing at 152F I was really over 160F. I switched to a digital thermometer and haven’t had any problems since.
I use an old Valley mill. The gap is indexed and not infinitely adjustable. The smallest gap gets me the best crush but if I try it on the first pass the free-spinning roller stalls and it’s a pain to get it restarted. So I need to double crush. First pass on the wideer gap and second on the tightest gap. The result is a beautiful crush with the endosperm crushed to fine grits and the husk is almost left whole.
As far as efficiency goes, if I go by Kai’s first runnings chart in his understanding efficiency article my conversion efficiency is usually near or at 100%. After lautering and trub loss I’m down around 75% brewhouse efficiency.