Milling

(In progress)

Grain (also called grist) consists mainly of starch granules inside a husk. Before the mash, it must be mechanically crushed using a grain mill in order to break open the husk and expose the starch and enzymes inside. The starch granules (endosperm) are also crushed in the process, increasing their surface area. In general, the crush quality affects the mashing process and saccharification time, lautering, efficiency, fermentation, and the color, taste, and overall character of the beer.

Basic Milling Process:

1. Set the desired mill gap.
2. Weigh out the grain on a scale per the recipe specifications.
3. Optional: Condition the grain. (See below)
4. Add the grain to the hopper.
5. Spin the drive roller to run the grain through the mill (into a container or directly into the mash tun).

Grain Mills

Corona Mills, Food Processors, or Rolling Pins

• It is possible to use these low budget options (example), but you'd be better off buying your grain pre-milled if you're not ready to invest in a mill.
• In other words, skip the aggravation, save your money, and get a roller mill.

2-Roller Mills

• Malt Muncher 2 Roller Grain Mill (Where to buy: MoreBeer, Amazon)
• The Barley Crusher Grain and Malt Mill (MoreBeer)
• The Evill Twin Grain and Malt Mill (MoreBeer)
• Monster Mill MM2 Grain Mill (MoreBeer)
• https://www.crankandstein.net/index.php?main_page=product_info&cPath=6&products_id=9
• https://www.austinhomebrew.com/MattMill-Kompakt-Grain-Mill_p_7192.html

3-Roller Mills

• Malt Muncher 3 Roller Grain Mill (MoreBeer, Amazon)
• Monster Mill MM3 Grain Mill (MoreBeer, Amazon)
• Kegco KM11GM-3R Grain Mill (Beverage Factory, Amazon)

Motorized Mills

• Motorized MaltMuncher Pro (MoreBeer)
• Ss Brewtech Grain Mill (MoreBeer) User review LOB thread
• MoreBeer!® UltiMill - The Ultimate Grain Mill (MoreBeer)

Reasons to buy a mill

• I like, big, husks, and I cannot lie!
• Freshness - Milling immediately before brewing results in the freshest malt possible (especially important in low oxygen brewing).
• Control - Adjusting the gap and speed allows you to tailor the crush to your own system and maximize efficiency.
• Consistency - When other sources mill your grain, the crush size may be inconsistent.
• Grain conditioning - Milling at home gives you the option to condition your grain.
• Cost savings - Avoiding a milling fee and buying grain in bulk are two ways to save money, and the mill will eventually pay for itself.

Bearings vs bushings? Bushings wear out over time. However, if you keep the bushings lubricated with just a drop of mineral oil every now and then it works MUCH nicer.

Knurled vs fluted?

Stainless steel vs cold rolled? For most brewers, hardened steel is the best option for roller material due to its durability. Stainless steel is more expensive but has better protection against corrosion. If you live in a damp or coastal region, stainless might be a good option.

3-roller vs 2 roller

The 3-roller mill has several advantages:

• It provides less husk damage, which aids in lautering.
• It more fully separates the starch from the husk, while providing superior grain feed, even with wheat.

There are also a few disadvantages to a 3-roller mill:

• Additional power is required to drive it.
• Brewhouse efficiency may be higher than initially expected.
• They are generally more expensive.

The 3-roller works by pre-crushing the grain in the preliminary gap between the top two rollers, then opening the husk to expose the crushed kernel in the secondary gap with the third roller. The top gap is fixed at approximately .060" which easily pulls in both wheat and barley, softening the starch without tearing up the husk.

Gap Setting

0.049" dry crushing on a 3 roll at around 70 RPM, courtesy of Bilsch on LOB

The optimal mill gap setting is dependent on your mill, your brewing system, and other factors. Therefore there is not a one-size-fits-all gap setting. For some brewing systems, the husks must be disintegrated as little as possible during milling because they are required for lautering. For other brewing systems such as "Brew In A Bag" (BIAB), the grain can be very finely milled if desired. Less well modified malt requires finer milling.

A feeler gauge should be used to adjust the gap setting. Use a feeler gauge. Its a tool that you can buy at almost any good autoparts store. It is a stack of small pieces of metal in different thicknesses. They are bound together, and marked for thickness. To achieve gaps that are not the same thickness as a single blade, stack multiple blades together to add up to the gap you want to measure. The blades should go into the gap between the rollers with a minimum amount of force, and should not be crushed in the gap. Try to adjust the gap on both ends of the roller to be the same. There is some slack for a tapered gap, but this will put unnecessary stress on the bushings.

On the models with adjustment knobs you can mark an arrow on the knob, and then turn it to set the gap at different points and mark on the frame what the gap is at the corresponding knob position. This way you can repeat different gap settings without even getting out your feeler gauge.

I have a three roll mill and am recirculating so I use 0.049" for the gap. I have a 2 roll monster mill set at 0.034”. If I condition and slow mill it’s a good crush, but if I just go quick at that gap, there’s too much flour.

For recirculating systems, often a gap in the range of 0.030" to 0.050" is appropriate.

Everyone always talks about gap but I really feel that milling speed has more effect on a good crush then the roller spacing, or conditioning.

The gap on the 2-roller mills should be set somewhere around .037 - .055". You will need to assess the crush, and determine if the gap should be smaller or wider. On the two roller mills you will find a point at which the mill will stop feeding the grain when you close the gap too tightly. You will run the drill, but the gap is too small for the grain to fall into, and the drive roller will just spin and not feed. How you crush your grain is up to you. It is important that you experiment with different settings and find out what works best for you. Generally it is not necessary to change the gap frequently. Most grist will crush just fine using the same gap. Unless you have extremely dry or moist malt, you shouldn't have to adjust frequently.

Bryan just recently brought to my attention the effect of crush size, which runs counter to some of the presumptions behind conditioning to achieve a finer crush supposedly allowing higher efficiency and attenuation. For separate reasons, I've been opening my mill gap of late, and have seen no reduction in efficiency or attenuation; in fact, possibly the opposite.

Uncrushed kernels represent a direct loss of extract, and what you find when you examine coarsely crushed malt samples is a proportion of same. Thus the large gap (relatively speaking) in brewhouse efficiency between coarse and normal crushed malt. In a normal sample, you will find no uncrushed kernels. And therefore, a fine crush gives only a small increase in efficiency, but a large increase in lauter time (and difficulty).

For your first trial you may have to make a best guess. With a roller mill you should still use the feeler gauge set to make sure the gap is uniform from end to end. If you have no test sieves, you need to adjust the mill by carefully evaluating one-cup samples. Start with the stock setting for a roller mill, or set screw two turns out for a corn mill. Keep tightening the gap until you no longer find any uncrushed kernels. The problem with the eyeball assay is that even a one-cup sample requires a lot of patience to pick through. Obviously, the coarser the crush, the more intact kernels there will be, and the easier it is to find one. However, as you tighten the mill down uncrushed grains become harder to find — or to be sure they are not to be found.

Driving the Mill

Motor vs drill vs hand crank vs mule?

100RPM amazon gear motor ? I assume you're referring to the Makermotor gear motor? I bought the 50 rpm because I was concerned the torque of the 100 rpm, at 2.2 ft-lb, wouldn't be enough. I'll be interested to hear how the 100 rpm motor works for you because 50 rpm is painfully slow.

I aim for about 120 RPM. I also like to mill slower, about 70 is what my motor puts out.

The best speed to run home brew mills is around 150-250 RPM. Running it faster will create more flour, so slower is generally better, whatever works without your drill or motor stalling. It usually takes a little more torque to get the mill going than to keep it going, so you will have to give it some more power to start the mill, and then slow it down once you are milling.

Crushing speed is MUCH more important then conditioning. If you crush fast you will get shredding. The slower you crush the more intact husks/hulls you will get. My motor is around 75rpm, and I stopped conditioning pretty much all together. I only wet the grain to help feed, its just a spritz or 2 and immediately crush. Eye your mash after lautering. If you noticed a lot of uncrushed kernals after back off the water. My efficiency slowly raised the more I lowed the conditioning water amount, and I saw less uncrushed malt in the tun. Crush is more coarse now going to deny that, but I didn't see any down sides beyond that.

For most mills, you want to be able to start slow and run at about 175-200 rpm for getting the perfect crush.

I also gave up conditioning after going 3roll and get a really awesome grind. However IMO you have to be turning fairly slowly (100 or less) for ripping not to happen.

Other Considerations

Oxidation processes start immediately after milling and can have a negative impact on the subsequent beer quality. Therefore the time between milling and dough-in should be kept as short as possible. Microbiological problems may also become a concern if it is stored for too long after conditioning.

Commercial low oxygen breweries fill all areas containing milled grain with inert gas (CO₂ or N₂). Low oxygen home brewers may also attempt this by flowing inert gas into the bottom of the mash tun and milling directly into it.

With my current system, I have Co2 hooked up from below, mill directly into mash tun, my mill sits on a plate that I made for sitting on top of the kettle, when complete I remove the mill, place the mash cap on top with Co2 still flowing, and continue the purge. With my new system, I'll mill into the mash tun, pull a vacuum, purge, and repeat until all o2 is removed.

I pre-underlet CO2 and some during milling too. I don’t run it constantly because the regulator starts to freeze up and it also starts to freeze my MT ball valve and chill the FB. The net result, if I run too much CO2, is that I come up short on strike temp because of the water passing through a super-chilled ball valve. Then, when milling is done, I turn the CO2 back on and then remove the platform to which my mill is mounted and cap the grain. Some air will get in. -- solution: Get a cheap hair dryer, connect it up to blow on your regulator, no more freeze ups.

My process was similar to others. My mill is mounted to one of those round pine table tops (identical to the one shown above), large enough to cover the entire MLT. -Purge MLT from the bottom for 10 minutes with grain in the hopper. -Mill with CO2 continuing to flow. -Add grain to hopper as needed. My goal was to keep it pretty much topped up so the CO2 I was purging with might purge the grain in the hopper too. Not convinced it was effective, but made me feel better. -When milling complete, remove mill, place mash cap and lid. -Move CO2 connection to MLT recirc return and continue purging. -Underlet -Turn off purge once water gets close to the level of the return connection. -Finish underlet.

I mill into an unpurged empty vessel. I purge while the water preboils and chills.

Purging a covered mash tun at 1-2 psi for about 10 minutes had been shown to effectively remove the vast majority of oxygen in the vessel. Dry ice can also be used to purge: put the dry ice in a jar with water and connect it with tubing to the mash tun.

Purging isn't an absolute requirement, but it is a good tweak to the process. I wouldn't get hung up on it initially. After you've got the rest of the process down its something to look at. The point of purging is dilution. Unless you are using some type of displacement method the best thing you can do is dilute whats there. Realistically you won't be able to put enough of a vacuum on any brewing vessel to do an effective purge. Your best bet is continuous flushing with inert gas.

"Flaked" or "rolled" adjuncts do not need to be milled, although they can be run through the mill with the rest of the grain if it is convenient.

Sieve testing

• http://www.lowoxygenbrewing.com/forum/viewtopic.php?f=11&t=1532
• https://beerandwinejournal.com/malt-sieves/
• https://byo.com/article/the-perfect-crush/
• http://brewlikeapro.net/maltmilling.html

We want the husks to be as intact as possible, not only for filtering, but also because finely shredded husks can cause astringent off flavors due to tannin extraction.

A fine, flour-like powder might also leach too many undesirable substances into the wort and beer, such as silicates, lipids, husk-derived tannins, and large-molecular proteins, which can cause deposits, hazes, and a shorter shelf life.

The husk contains tannins and harsh bitter flavour compounds that will impart a negative flavour to the finished beer, so we do not want to extract them.

At a molecular level, the cell walls contain beta glucans which are directly related to viscosity and therefore the rate at which the wort can be extracted, whether recirculating or transferring to the kettle. Grinding the grain (and husk) to a flour will break down the cell walls and increase the viscosity of your wort, increasing the likelihood of the dreaded ‘stuck mash’. There is absolutely no need to shred the grain to a powder.

Milling your own grain allows you to use the freshest possible ingredients and allows you to dial in your crush for maximum efficiency.

Gap settings are not universal or set-and-forget. The crush should be monitored every milling to ensure the barley you're working with is being properly crushed. Barley is an agricultural product and friability and kernel size assortment vary from maltster-to-maltster and even harvest-to-harvest.

Excessive milling promotes the extraction and solubilization of compounds whose presence causes the increase of undesirable characteristics to wort and beer, e.g., sensory properties such as an excessive bitterness or viscosity. Undesirable compounds include phenolic compounds, which, if present in large quantities, cause problems such as excessive bitterness, color changes, and excessive formation of trub [6,7]. Approximately 70–80% of the total polyphenol content of beer comes from the malt husk; its transfer to the wort is influenced by cereal milling [8].

Cleaning: Paintbrush +/- compressed air.

Conditioning the Grain

Aside from cellulose, the husks also contain polyphenols and other compounds that create an unpleasant bitter taste and have a negative effect on the colloidal stability of the beer. Dry husks fragment easily and lautering becomes more difficult if the husks disintegrate too much. However husks become more elastic when they are moist, making them easier to protect and subsequently making lautering more rapid. Wetting the grain is called "conditioning". The goal is to increase the most content of the husk by approximately 2%.

http://www.lowoxygenbrewing.com/uncategorized/grain-conditioning/

Process:

1. Add water to a small spray bottle. Generally the amount of water should be about 1-2% of the weight of grain.
2. Spray the grain evenly while stirring (e.g. with your hand) until the grain becomes pliable.
3. The grain may be milled a few minutes after wetting.

Advantages:

• The grain can be ground more thoroughly (tighter gap).
• Husk volume increases (looser grain bed).
• Efficiency and attenuation are increased.
• Conversion is faster.
• Reduces dust.
• Decreased risk of dough balls.

Disadvantage:

• Requires labor.

I regularly use 24+ pounds of malt, weigh it out in buckets, then pour a thin layer into a large plastic tub, spray it down, pour another layer, spray it, and repeat until done. Easy peasy, works great.

I do 100L batches with malt bills anywhere from 20-30+kg and still condition my grain. I just have a large tote and a flexible misting nozzle for my sink hose. I turn the mister on and stir with my mash paddle since it no longer stirs the mash. Works like a charm and is actually easier and more enjoyable than spraying 7kg with a spray bottle, this method doesn't involve any hand cramps.

I have the mm3 pro powered by a low speed drill. I don’t condition any more because I find it’s not necessary. But the conditioned crush was absolutely beautiful. Endless piles of barely torn husk. The mash wasn’t noticeable better though. So I eliminated that 10 minute effort from my brew day and focus elsewhere. I found it made a beautiful crush but didn’t make any noticeable difference in dough balls or lautering so I stopped wasting my time. Maybe if i was doing batches with 10lbs of grain I might do it, if only for the dust control, but it’s a huge pain to do with my typical 20-33lb grain bills.

All I do for conditioning is spritz the grain while using my hand and arm to stir the measured grain in the bucket. The extra 5-10 minutes it took, I feel, was worth the elimination of doughballs and less mess on the bottom of the mill.

I still do mine. I like the qualities of the crush (more intact husk, less dust, etc) enough that I have never stopped. Same procedure as you, spray bottle and stir with my hand.

I still condition. I do it now mostly to keep the dust down during milling. The quality of the crush didn't change much for me pre/post conditioning and I never had doughball problems before conditioning, either. But, I mill by hand so my RPMs are not high and thus I'm not shredding to powder.

I still condition my malt for the reduction of dust in my mill like you and I believe I get a better crush as I'm still only using a Cereal Killer mill, although I simply take 30-50ml of pre-boiled water and pour it on the malt and mix it up by hand.

I still condition as well. Doesn't take much time to do, and I am getting good results with it.

I also condition the grain. Stirring with spoon in one hand, spraying with the other. Takes about 1-2 minutes, then I let it sit for 7-10 minutes prior to milling. Keep the dust to an extreme minimum as well as keep the husks from shattering - caveat is that I have a 2-roller mill.

I stopped doing it because I was losing a lot of efficiency. Like 10-15 points solidly. Stopped conditioning and I'm back in the right range again. Haven't touched the mill gap setting so I have no idea why this is the case. Other brewers have observed no change in efficiency when conditioning.

my mill isn't the greatest, and it seems to grip the conditioned grain much better and therefore mills faster even at the same speed.

grain conditioning is helpful with keeping the husk more "intact" to protect the acrospire and polyphenols from being exposed to air right off the bat which helps to minimize some oxidation prior to dough-in. ??

To be clear, I don't measure it. I just spray some on and mix it up, then add more if I think it needs it. That's what I'm doing for better crush. I can almost do it by feel. It's doesn't seem dry and lose. It's not sticky or clumpy either. It stops feeling dry and friable. I think I notice it most in the sound of it. If you pick up a bunch, the sound it makes as it flows back down shifts a bit and I think that is what I'm really going by. I also don't bother measuring conditioning water and go by feel.

Our mills don't like wet grain.

When I started conditioning I felt like the kernels slightly expanded and didn't want to go through the gap as easily and so I did widen my gap.

I made a number of process tweaks a year or so ago and took a huge efficiency hit in the first 3-4 batches. In my case I narrowed it down to grain conditioning. I don't know if it's something with my particular mill or gap setting or what, but conditioning with 1-2% water very obviously lessens my efficiency, and so I've moved away from it.

One study tested the effect of grain condition using a disc mill (like Corona style). Adding 10-20% moisture actually decreased the average particle size of the milled grain compared to dry milling. Only at higher moisture percentages did particle size increase. The conditioned samples gave a higher yield compared to the dry sample, and phenolic compounds were also increased. This result indicates that wet milling, using up to 30% moisture, increased the extraction of sugars during mashing.

Adding a Motor

• http://www.lowoxygenbrewing.com/forum/viewtopic.php?f=2&t=694
• http://byo.com/stories/item/1166-motorize-your-grain-mill-projects

I've been very pleased with the 50 RPM Makermotor I paired with my three roller mill. Makermotor 3/8" D Shaft 12V DC Reversible Electric Gear Motor 50 RPM https://www.amazon.com/dp/B01N8YDOC9/

If you will pulley drive, we recommend you use at least a 1/2 HP motor for our small 1.5" diameter roller mills, and 1 HP for our larger 2" diameter roller mills. If you will direct drive with a gearmotor, we recommend you use at least a 1/4 HP motor for our small 1.5" diameter roller mills, and 1/2 HP for our larger 2" diameter roller mills. Use a capacitor start capacitor run motor if possible. They have much higher starting torque and should be able to start milling after the hopper is loaded. If you don't have a capacitor start motor, you may just have to have the mill running when you load the hopper. Get the RPMs down as much as possible. To do this you will need to use as slow a motor as you can get, and put a very small pulley on it, and put as large a pulley as possible on the mill. The biggest problem with this approach is that the pulleys end up being very large.

Most AC motors run at the slowest speed of 1725RPMs. This means that you need to reduce the speed by a minimum factor of 10. So you will need a mill pulley that is 10 times the diameter of the pulley on the motor to get down to 172.5 RPMs assuming your motor runs 1725 RPMs. When using pulleys to drive the mill it may be preferable to widen one flat on your mill's drive shaft using a metal file. The flats are designed for drill driving, and will work better with a pulley setscrew if they're wider. This is easily accompished using a metal file with the drive roller held firmly in your bench vice.

Pulleys to complete a motorization project are readily available from several sources including Grainger, and McMaster Carr. Look for a small pulley with a diameter of 1.5" or less, and a large pulley to mount on the mill of at least 10" with 12-14" being preferable. Worth noting is that usually the pulleys will have different pitch diameters depending upon the width of belt you use. If you use a narrower belt, it will ride lower down in the pulley groove, and effectively reduce the diameter of the pulley.

There was a very informative article written in BYO a while back, that has all the specific information you will need to complete your project. We worked directly with the author to provide accurate information. Gear reduction motors are also an option but they are usually out of the price range of most home brewers. If you can find one used for a good price, I have heard of several folks using them sucessfully, but you must make sure you have enough torque to drive the mill, or it will stall while grinding.

How can I build a base/hopper? What is the best way to mount my mill?

The simplest base is just a piece of 1/2" or 3/4" thick high density fiber board at least 8" wide and 18" long with a hole for a funnel over the gap, and four mounting holes for the mill. Make sure to drill the mounting holes oversized (at least 5/16") so that there is clearance to properly align the frames for perfect spinning of the idler rollers.

I personally have found it easiest to mount my mill underneath the base and cantilever it out over the edge of my brew stand at a height that is just above my 5 gallon bucket that I mill into. The mill is mounted at one end of the plywood and the other end is screwed into my brew stand. This way it hangs out so I can place my grist bucket under it and attach the drill.

You can also place the base on top of your grist bucket with the mill underneath and the shaft sticking out of a slot cut into the bucket. You can also top mount the mill and place another piece of fiber board on top of the mill with a hole or slot cut in it for the hopper/funnel.

All of our drill drive mills have threaded mounting holes on the top and bottom of the end frames for whatever mounting configuration you can come up with. We include plans for a simple base and hopper configuration like what I use. The drive shaft can turn clockwise, or counter clockwise, as long as it spins and pulls the grain down into the gap. We always like to hear how people are using their Monster Mill, and if you have a Brewing web page we would like to link to it to show other folks how Monster Mills can be configured.

See Also

• Mills and Milling by Dave Miller (Brew Like A Pro)
• https://byo.com/article/the-perfect-crush/
• If you're really into DIY: Suggestions to help build a mill from scratch
• http://www.brewingwithbriess.com/Assets/Presentations/Briess_2007CBC_Practical_Milling.ppt
• http://www.brewingwithbriess.com/Malting101/Technical_Presentations.htm
• https://www.beveragefactory.com/blog/home-brewing/milling-your-own-grain/
• https://makebeereasy.com/grain-mill-for-home-brewing-should-you-bother/
• https://www.brewcabin.com/grain-mill/
• https://www.sciencedirect.com/science/article/pii/S0032959203004400
• "Haze formation in beverages"
• Conventional and alternative principles for stabilization of protein and polyphenol fractions in beer
• O processo de fabricação da cerveja e seus efeitos na presença de polifenóis (The brewing process and its effects in the presence of polyphenols)
• Use of malt humidification water from wet grinding as raw material in the manufacture of beer
• Wet-Milling of Cereals
• Dry and wet milling of malt. A preliminary study comparing fermentable sugar, total protein, total phenolics and the ferulic acid content in non‐hopped worts
• https://youtu.be/DpI4jh8Uj44
• https://youtu.be/QdScbJFJvRI