Home   About Me   Design Logic  HERMS Design Specifics  HERMS Limitations

The HERMIT Brewery   Portability    Gadgets    Lessons Learned  Recipes  Links  Contact Me

Other Gadgets

6 -Tap Beer Fridge  SS Counter Pressure Bottle Filler  Fermentation Chiller

Counter-Flow Wort Chiller    Carboy Washer    Auto-Siphon

Grain must be crushed prior to mashing.  Crushing can be done a variety of ways but the most consistent and efficient results come from using a roller type mill.  The grain is pulled through two rollers set a given distance apart.  The rollers have a knurl on them which pulls the grain through.  The grain kernel is broken into small pieces and the grain husk is shed, but kept whole.  The intact grain husk is important to provide a filter bed during the sparging/lautering process.

When you finally make the decision to go all-grain, one of the things you will find is that ingredients are a lot cheaper.  Grain is less than $1.00 per pound in bulk (50 lbs).  You can buy this grain pre-crushed, but it will not stay fresh for as long as uncrushed grain.  Stale grain can result in stale tasting beer and low extraction rates.  Most homebrewers eventually end up purchasing their own grain mill so that the grain can be crushed just prior to mashing.

When I was in the market for a grain mill, I had already seen people with hand crank mills.  This looked like a lot of work and I didn't even want to fool with it.  Besides, the mills usually had really small hoppers (less than 2 lbs) and you had to constantly refill them or have a partner during the process.  Some people use an electric drill to motorize their mill, but I really didn't like that approach either.  I wanted a motor mounted to the mill with a large hopper for the entire grain bill.  This meant that I would have to design and build it myself.

The key component was, of course, the mill.  After looking at what was available I chose a mill made by CrankandStein.  This is a well made mill with adjustable rollers, however, it requires mounting to a stand or board plus supplying a hopper.  Since I was planning to build my own anyway, this mill was perfect.  One of the rollers is turned externally (i.e. a motor or hand crank) while the other turns freely (idle).  When the grain is pulled through, the friction of the grain on the rollers turns the idle roller.

The construction materials were basically 2 x 4's and plywood.  I made the frame just large enough so that a 5 gallon bucket would fit underneath.  The hopper is large enough for about 18 lbs of grain.

In selecting a motor for you mill, you have many options.  You should look for a motor that is at least 1/4 Hp.  You don't have to buy a new motor.  Again, as with the refrigerator project, think like a homebrewer.  Contact a used appliance shop.  They usually have refurbished motors from washing machines or other appliances.  Mine came from a garage door opener.  You should also look for a motor with a capacitor start.  This means that the motor can start under load (in this case, with grain already in the hopper).  If your motor does not have a capacitor start, you may have to pour grain in after the motor has started.

Next is the motor speed.  Electric motors come in a variety of speeds (RPM's) but are usually well in excess of what we need to grind grain.  When grinding grain, you should not exceed 300 RPM.  As the speed increases, the mill tends to shred the grain/husks rather than crush.  This means that the motor speed must be reduced via some kind of belt and pulley system.  My motor is rated at 1000 RPM.  I used 2 pulleys from Grainger sized 1.5" dia (1.35" pitch dia) and 8" (7.85 pitch dia), PN# 3X892 and 3X926 respectively).  By attaching the 1.5" pulley to the motor and the 8" pulley to the mill, I achieved a 5.8 : 1 speed reduction, or 172 RPM.

Finally, you have to mount the motor.  It is important that you leave some room in the design so that the belt can be installed and removed easily.  I installed the motor on a block and then hinged the block so that the motor pivoted.  A bracket is attached to the other end of the block that rotates down over a threaded stud on the frame.  A nut is screwed onto the stud to provide belt tension.  For safety, you should probably install a guard over the pulley system, however, I don't have one (do like I say, not as I do).

Next, simply install a 2-way light switch and a plug and the job is complete.

This is the front of the grain mill.  A five gallon bucket underneath catches the crushed grain.  The light switch on the front controls the motor.  The hopper holds about 18 lbs of grain.

The motor on my mill is rated at 1000 RPM.  An 8" and 1.5" pulley reduce this speed to 172 RPM which is ideal for grinding grain.

The motor is mounted to a block that is hinged at one end.  A bracket attached to the opposite end rotates down over a threaded stud in the frame.  A nut is screwed down to provide belt tension.

The picture at the left shows the motor rotated toward you so the belt can be slid onto the pulley.  The picture on the right shows the belt installed and tensioned.

The CrankandStein Mill.  It comes with 2 rollers, the end plates and some mounting screws, that's it.  The rollers have an adjustable gap via a knob at each end of the idle roller.

Motorized Grain Mill