Motorizing a Country Living Grain Mill for 12-volt Battery and Solar, by I.S. – Part 1

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Introduction

The Country Living Grain Mill is a robust mill that will last for generations and is a fine choice for any home or retreat. It has been designed to be motorized easily, however the manufacturer’s motorization kit is expensive and operates on 115 volt AC power, thus requiring grid power, an inverter, or a generator. The following article will describe how to power your Country Living Grain Mill from 12 volt batteries or solar panels for less than $200 (excluding the power source and associated wiring). Currently, all necessary materials are readily available.

Tests have shown this setup can easily mill fine flour using nothing more than a car battery, drawing 12-14 amps. It can also be powered purely off solar, although when using panels producing 17 volts at 8.8 amps (150 watts), the grind had to be backed off to keep the motor from bogging down. The best tested method was powering the mill from the car battery, while using the solar panels to replenish the battery. One test ran the mill continuously for one hour with combined battery/solar power. The finished product was an almost fully charged battery and eight cups of fine flour.

While this was written specifically for the Country Living Grain Mill, the principles are applicable to any quality mill with a v-belt pulley. The appropriate formulas have been included for those who wish to use a different motor, speed, or method.

This article is divided into two parts for posting, but within it are two distinct projects. The first and primary project will give you a functioning motorized mill. For those who wish additional protection and portability, the second project adds to that base and transforms it into a sturdy crate, thus allowing easy transportation or storage of the entire assembly.

One final note: According to Country Living, motorizing your grain mill with a motor, other than the one they sell, will void your warranty.

Tools Required

  • Tape Measure
  • Square or Straight Edge
  • Pencil
  • Drill Bits – 1/8, 1/4, 3/8, 5/16
  • Saw (Both a Skill saw and a compound miter box saw work best, but even just a handsaw would suffice.)
  • Screwdriver
  • Hacksaw (for cutting a section of continuous hinge down to 6”)
  • Alan Wrenches (for mill and motor pulleys)
  • Wire Cutter, Stripper, and Crimper

Additional tools required to build the protective crate:

  • Woodworking Clamps, 2 minimum
  • Wood Glue

Parts required for the motorized base: (2014 cost of the following was $160, excluding the mill)

  1. Mill – Country Living Grain Mill (with power bar and handle removed).
  2. Motor – 12 volt DC motor of approximately 1/9 horse power. This project uses a 12VDC Duoyou 179 RPM Inline Gearmotor available from SurplusCenter.com for $79.95. This motor was chosen after considering the following criteria:
    1. Shaft Horse Power (SHP). Country Living’s motor is 1/9 HP (0.11 HP). It is possible to motor the mill with less power, but it may bog down as the grind is set to fine and, thus, require running the flour through the mill twice or more to achieve fine flour. For reference, SHP = Torque (ft-lbs) x RPM x 0.00019. For this motor, that formula is: 0.11 SHP = 3.25 ft-lbs (39 in-lbs) x 179 RPM (no load) x 0.00019.
    2. 12 volt DC power. This motor’s listed max load is 12 volts at 12 amps (144 watts).
    3. Use a gearmotor with a slow enough output so as to turn the mill no faster than 60 RPM. Faster than this will heat your flour and destroy nutrition. The output of this motor is 179 RPM with no load. Having a slower output allows you to skip the complexity of an intermediate pulley. Make certain the gears are metal and can withstand heavy use.
    4. Rated for continuous duty and clockwise turning (viewed from shaft end) or reversible.
    5. Replaceable brushes.
    6. Standard size shaft with keyway. This motor has a 5/8” shaft with key. Many motors on the market have smaller D shafts and do not fit most common pulleys.
    7. Integral motor mount.
  3. Motor Pulley – The motor pulley size is determined by the speed at which you wish the mill to turn. Motor RPM x Motor Pulley Diameter = Mill RPM x Mill Pulley Diameter. This project uses a 4.45” OD 5/8” Bore 1 Groove Pulley, also from Surplus Center for $12.95. For the calculations, the datum diameter on this pulley for an A-type belt is 3.7”. Thus the formula is: 179 RPM (no load) x 3.7” = 57 RPM x 11-1/2”. Ideal milling speed is 50-60 RPM.
  4. Belt – Type-A (1/2”) v-belt with a 48” outside length. This is available from the Surplus Center for $4.40.
  5. 3/4″ Plywood, 2’x4’ minimum size – This will become the 24” x 16” base board, the 24” x 16” crate top (if you build the crate), and the 6-1/2” x 9-1/2” motor mount. These can be bought in a small 2’x4’ size at Home Depot for $20. Actual thickness is 23/32 or 0.72”, but for simplicity we will refer to it as 3/4″.
  6. Hinge – 6” Continuous Hinge (a.k.a. Piano Hinge). The smallest length is typically 12” and will need to be cut down to 6” with a hacksaw. This project uses half of a 12” x 1-1/2” stainless continuous hinge, which is roughly $10 from the Home Depot. In a pinch, a simple door hinge will suffice (the first two prototypes used door hinges), but the continuous hinge will fare better.
  7. Hardware for the basic mount (the total cost of all the following hardware was less than $18 in 2014):
    1. For the mill, four 5/16” x 1” hex bolts, four 5/16” washers, and four 5/16” T-nuts. The actual mill holes are 3/8” but sometimes there are variations with the enamel thickness. 5/16” provides enough tolerance for fit and adjustment.
    2. For the motor, four 1/4″ x 1” hex bolts, four 1/4″ washers, and four 1/4″ T-nuts.
    3. For the 6” continuous hinge, six #8-32 x 3/4″ Flat Head Phillips Machine Screws (countersunk heads) and six #8-32 T-nuts.
    4. Four Anti-skid pads for the bottom of the base. Everbilt Heavy Duty Pads, 1-1/2” diameter, from Home Depot. They are a rubberized pad that mounts with a screw.
  8. Electrical – Of the following, only the toggle switch and aluminum to mount it were included in the total $160 cost; the cost of connectors, wire, and battery clamps may vary significantly depending on your plans. This list includes the items you would need to connect it to a 12v battery.
    1. Toggle switchrated for 20amps along with two connectors (ring or blade depending on which toggle switch you get) and a means of mounting. It (this project) uses a piece of aluminum 1×1 angle mounted to the rear of the motor. General costs will be $5 for the toggle switch, $2 for a box of miscellaneous ring connectors, and $6 for a piece of 1” aluminum angle from the Home Depot.
    2. Connectors. This project uses Anderson Power Pole connectors rated for 15 amps. Four of them are around $5.
    3. Wire. This project uses a piece of 10 gauge 2-wire to connect to a car battery. Typical cost is around $1.50/foot or less.
    4. Battery clamps, 50a rated from Home Depot. $3.29

    Additional materials for the crate: (2014 cost of the following was $60)

  9. 1/2″ Plywood, 4’x4’sheet minimum. This project used a 15/32” (0.451) 4’x4’ panel from the Home Depot for $23. You will cut it to the following sizes:
    Mill Plans 1

    1. Two 15”x24” panels
    2. Two 15”x15” panels
    3. One 16”x24” panel for the top of the crate, unless you use a piece of the 3/4″ plywood.
  10. 1×3 pine board. You will need 103 linear inches. Either a 10’ board or two 8’ boards. 8’ boards are about $8 each. Cut to the following lengths:
    1. Two 24” long pieces (for underneath the base board)
    2. Two 16” long pieces (handles on the crate ends)
    3. Rip down to 1” widths for the following:
      1. Two 14-3/4” long pieces (these will mount to the top of the base board, inset 5/8” from the edges, to center the crate over the base board)
      2. Four 14” long pieces (these will reinforce the corners of the crate where the 1/2″ ply joins together

        3. Mill Plans 2

  11. Four draw or butterfly latches. This project uses Reliable Hardware Company Medium Butterfly Latches, available from Amazon for $4.05 each. As these do not come with hardware, you will need the wood screws listed below and eight #6×3/4” Phillips flat head machine screws with washers and nuts. Hardware cost was $2.50.
  12. A box of #6 x 1-1/4” wood screws. You will need at approximately 70 screws. A box of 100 is $5 from Home Depot.

Instructions

  1. Create and Prepare the Base Board
    1. Cut the 3/4″ plywood to a 24” x 16” piece. This will be the base. The long sides are the front and rear.
    2. Locate the Grain Mill mounting holes. The Country Living Grain Mill has a base measuring 3-3/4” x 5-1/2”. It has four 3/8” mounting holes on a 2-5/8” x 4-5/8” pattern. The quickest and easiest method to locate these holes is to place your grain mill on the base board itself, pulley on the rear side, with the left edge of the base 5-1/2” in from the left edge and the rear edge of the base 4” in from the rear edge. If you wish to manually locate the bolt holes:
      1. Measure 6” in from the left edge and draw a line parallel to the left side. Draw a second line 10-5/8” in from the left edge. You should now have two parallel lines 4-5/8” apart.
      2. Measure 4-9/16” from the rear edge and draw a line parallel to the rear. Draw a second line 7-3/16” from the rear. You should have two parallel lines 2-5/8” apart. They will intersect the two previous lines giving you four bolt locations. Confirm these are correct by placing the mill over them and observing each cross is centered in the bolt hole of the mill.
    3. Drill the mill mounting holes with a 1/8” pilot drill, then with a 3/8” drill. Press the four 5/16” T-nuts into the bottom of the base board. You can use a 5/16” bolt and washer to tighten and fully seat them in the board, then remove the bolt and washer.
    4. Locate the hinge mounting holes. The hinge location is the key for successful belt tension. The pivot of the hinge (center of the hinge pin) should be parallel to and exactly 12” in from the left edge. For the 6” continuous hinge, position the end of the hinge 1-1/2” in from the rear edge. With the hinge opened flat, the hinge pin on the 12” line and the edge of the hinge 1-1/2” in from the rear edge, mark the locations of the mounting holes to the right of the hinge pin.
    5. Drill the hinge mounting holes with a 1/8” pilot drill, then with a 1/4” drill. Press three of the #8 T-nuts into the bottom of the base board.
    6. Finish base. If you do not plan on building the crate, you may finish the bottom of the base board at this time by mounting the four anti-skid pads– one near each corner– and then continue to Part II of this article. If you will be building the crate, do not mount the pads at this time. Continue to the following step.
    7. Add the two 1×3 by 24” boards to the bottom of the base board– one along the front and one along the rear. The rear board will need to be notched out in one small location so as not to cover up the T-nut underneath the hinge. Glue, clamp, and then screw them in place with #6 x 1-1/4” wood screws.
    8. Install the anti-skid pads on the boards you just mounted, spaced near each corner.
    9. Add the two 1×1 by 14-3/4” boards to the top of the base. Inset them 5/8” from either side, and from the front and back. These will be guides for your crate to fit over the base without bumping into your mill. Glue, clamp, and then screw them in place with #6 x 1-1/4” wood screws.