Greetings everyone! Today I went to brew a Bell's Official clone and ended up quite under my target. Last time I brewed this recipe I had SG at 1.053. This time I have SG at 1.041(checked with refractometer, double checked and verified with a hydrometer). The grain bill is 5 lbs Pilsner, 5 lbs white wheat malt, and 1 lb flaked oats. I do BIAB. Both times I milled the grains as I was heating up the water for the mash(Strike water was 157 degrees, mash was at 150 degrees at start, 145 degrees after 90 minutes). Used 7 gallons of RO water total with 4g Calcium Chloride and 7g Gypsum. I mash with 5 gallons of water(90 minutes), drain with some squeezing for 30-60 minutes, then do a sparge with the remaining 2 gallons of water, drain for 20-30 minutes with some squeezing, then hang the bag over the kettle for the entire boil(1 hour). So my question is what went wrong with my process? I didn't weigh the bags of grain, just assumed they were correct(two-5 lb bags and a 1 lb bag) and milled(could the measurements have been off?). This was my tenth batch since I started milling my own grains(the other brews had no problem, could my mill be getting loose? I just checked and a credit card barely goes through, it catches the rollers on both sides). Anyways this one confused the heck out of me and was hoping for some advice. Thanks!
Today had very poor conversion, any suggestions on how to avoid next time?
- Thread starter TkmLinus
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madscientist451
Well-Known Member
That's a mystery for sure. The only thing I can suggest is running the grain through the mill twice. I think hanging the bag over the kettle during the boil is over kill, just leave it in a colander over a bucket and 30 minutes into the boil toss in whatever is in the bucket and don't worry about getting any more.
[EDITS]
Wheat kernels are much smaller than barley, andideally should be crushed on a narrower gap (e.g., 0.025"), or they will remain mostly uncrushed.
Oat malt, Spelt, and such needs an even narrower gap (e.g., 0.015-0.018").
Since you do BIAB, you can crush all your grain on the finer gap giving you overall faster hydration and more complete conversion resulting in better mash efficiency too.
I do think your little dunk sparge definitely helps in rinsing out high gravity wort trapped in the grist, giving better mash efficiency over no-sparge processes.
Wheat kernels are much smaller than barley, and
Oat malt, Spelt, and such needs an even narrower gap (e.g., 0.015-0.018").
Since you do BIAB, you can crush all your grain on the finer gap giving you overall faster hydration and more complete conversion resulting in better mash efficiency too.
I do think your little dunk sparge definitely helps in rinsing out high gravity wort trapped in the grist, giving better mash efficiency over no-sparge processes.
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I will tighten up my mill gap and see what happens. While I feel that I have the gap on my mill set good and tight, is it something that needs to be periodically checked and reset? I just started milling my grains and am still relatively new to the process.
Yes mill gaps are subject to slippage (opening wider.) Some mills are more prone to this than others, depending on the gap adjustment and locking mechanism. So, checking periodically with feeler gauges is a good idea.
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I always check my crush visually, as it is simple to do before mashing.
Also, best to mill different types of grain (barley, wheat, oats, etc.) separately so that a good crush on the barley (largest kernels) doesn't mask a poor crush on the smaller kernel grains.
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was your mill RPM faster? i've noticed when i run my drill full bore. the kernels don't get crushed.....(at least with the 3000 RPM motor i tried out, without a pully)
Sounds like quantum mechanical tunneling. 
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Sounds like quantum mechanical tunneling.
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call it what you will, the grains weren't crushed...why i gave up on that attempt, bought a cheap harbor freight drill with a speed lock trigger, much better crush running slow...
That is interesting that you ask that, I was thinking as I was running my drill if I was running it too fast. For previous batches I ran my drill slower and thought this time "well let's see what happens" and ran it full speed(Dewalt 18v cordless drill). I assumed the grain was adequately crushed, but didn't inspect it very well. Thanks for the insight!
For grain used in brewing a linear mill speed of around 12"/sec (ips) is recommended. IIRC, I got that on a pro forum.
For a 1.3" diameter roller mill (e.g., Barley Crusher, Cereal Killer):
circumference = 1.3" * 3.14 = 4.082"
12 ips / 4.082" * 60 sec = 176 rpm
For a 1.5" diameter roller mill (e.g., an MM2):
circumference = 1.5" * 3.14 = 4.71"
12 ips / 4.71" * 60 sec = 152 rpm
For a 2.0" diameter roller mill (e.g., an MM2 2.0):
circumference = 2.0" * 3.14 = 6.28"
12 ips / 6.28" * 60 sec = 115 rpm
For a 1.3" diameter roller mill (e.g., Barley Crusher, Cereal Killer):
circumference = 1.3" * 3.14 = 4.082"
12 ips / 4.082" * 60 sec = 176 rpm
For a 1.5" diameter roller mill (e.g., an MM2):
circumference = 1.5" * 3.14 = 4.71"
12 ips / 4.71" * 60 sec = 152 rpm
For a 2.0" diameter roller mill (e.g., an MM2 2.0):
circumference = 2.0" * 3.14 = 6.28"
12 ips / 6.28" * 60 sec = 115 rpm
I agree the crush was a primary factor but that low ending mash temp probably hurt also. Keep it closer to 150.
I have a Cereal Killer mill. Certainly seems I ran the drill too fast. According to DeWalt, my cordless 18v drill runs about 400 rpm in first gear at full blast which is over double the 176 rpm. I will ease off the trigger next go round and run the grains much slower. While it stinks to have a screw up when brewing, I love the knowledge I gain from here when I ask about my mistakes. Thanks again!
Probably a barley/anti barley virtual pair...
They emerge from the quantum foam as a virtual pair, the barley gets crushed but the anti-barley slips past the rollers uncrushed or poorly crushed...
Then, what starches are there in the anti-barley have the wrong chirality so the enzymes get confused by the left-handed starches...
Clearly left-handed amylase is required...
That's 400 rpm under no-load.
Once you put grain in the hopper that speed will drop, possibly to half of that.
If it's still a bit fast, you can ease up a bit on the trigger once she's milling, it should reduce that speed close to the recommended one.
if your drill is that slow, then i'd keep looking for the problem. i mill around 200-400. i was thinking in the thousands of rpm.
doesn't look like it worked...
Many apologies, my attempt at a video was a flop....
There is a "whining" audio attached.
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yeah that's my mill...the video doesn't show much more anyway.
oh well, thought it would be fun to try, but a $30 camera isn't the best....
RufusBrewer
Well-Known Member
I have not run any numbers, but your water treatment does not look right. Double check against a couple water / grain bill calculators. Experiment and see what happens if you add some phosphoric acid to your water treatment.
Adjusted my gap to .025 and got much better conversion this time. Just got an OG of 1.053 from a kit that is supposed to be in the 1.040-46 range. Also ran the drill slower. Thanks again!
right on! i just calc'd 75% for 1.046, got 8.5lbs pale....and bump it up to 1.053, get like 85%, normal for most people! so now you should start trying to get consistency
(or try and get daring and push the envelope, lol)
RufusBrewer
Well-Known Member
As one prominent home brewers says, "Crush until you are scared, then crush a little more."
