Motorizing a Homebrew Grain Mill

DIY homebrew grain milling stationAnyone who knows me knows that I love to tinker.  My homebrewing hobby has spawn countless other hobbies – carpentry (brew stand, fermentation fridge, bar), wood turning (taphandles), electric (eHERMS, stir plate, brewbot), blogging (duh), soldering (eHERMS, brewbot)…you get the idea.

So, when I recently sat down to think about my next steps in my homebrewing journey, I wanted to focus on making some of the more tedious tasks easier and more enjoyable.  And that starts with milling grain.

I own an old barley crusher grain mill.  It works OK, but the rollers are getting a bit warn out, and I’m considering upgrading to a 3-roller Monster Mill soon (if you’re looking to buy me a Christmas gift…).  But this is not a post on mill reviews (I already did that), this is about the milling process.

When you are milling grain, if you’re like me then you have one hand either cranking or pulling the trigger on your drill, one hand holding the base on a bucket (because if you don’t, you inevitably will end up with grain all over your garage floor…yes, I’ve done that, and yes, I still brewed with it), and then you need another hand pouring your grain into the hopper.  And unless you’re one of the lucky ones with three hands, then this is a bit of a difficult dance.

The solution I’ve come to is to attach the mill to a stationary milling station (so I don’t have to hold the base and don’t risk grain on the garage floor), and to power the mill so that I only have to hit a switch instead of holding the trigger on the drill.  That frees up my two hands to measure grain and feed it into the hopper.

Motor vs Drill

You can motorize your mill by using an actual motor (used 1/3 or 1/2 HP motors work great), or you can use a low-speed corded drill as the motor.  Here are some pros and cons for each:


  • Can be expensive to purchase new, but easy to find used and can last a long time
  • RPM is usually 1750, but you want to mill your grain at about 200-300 RPM, so you’ll also need a belt and large pulley to lower the RPM by almost 10x, which is an added cost
  • Low RPM motors (less than 500 RPM) are very hard to come by and usually don’t have the horsepower needed to power a mill
  • Can be wired to an on/off switch fairly easily


  • Low-speed drills are hard to find used, but are inexpensive new (here’s one from Harbor Freights for $50)
  • Can still be mounted to your milling station using U-bolts
  • To avoid having to hold the trigger down, you need either a drill that has a trigger lock to stay on, or you need to find other means of holding the trigger down, like a zip tie
  • If you zip tie the trigger, then you should wire the drill into a power switch or plug it into a surge protector so that you can turn it on and off by flipping a switch

There are clearly some downfalls to either option, but being the price-conscious person that I am, and not wanting to get myself in over my head on a DIY project, I decided to opt for purchasing the low speed drill from Harbor Freights and using that as the motor.

I repurposed some of the wood from my old brew stand to build a milling station.  I had to use a second layer of plywood under the mill to lift the drive shaft up to be level with the drill chuck.  Once everything was aligned, I simply used a jig saw to cut out an opening below where the mill would be, so that the grain could fall through, mounted the mill to the table, then attached the drill.  The drill is held down to the table with a single U-bolt.

The low speed drill is variable speed from 0-500 RPM based on how tight you squeeze the trigger.  I wanted to hold about 200-300 RPM, so I used a zip tie to hold the trigger at about half-way.

The drill is then plugged into a surge protector that is mounted on the front of the milling station.  I can then use the switch on the surge protector to flip the mill on and off.

I also opted for a 41 qt trashcan under the table to catch the milled grain.  This allows me to fit all of my grain for 10-gallon batches into a single bucket, instead of having to use two 5-gallon buckets.

Let me know how you deal with the tedious task of milling grain – whether it’s just doing it the night before or if you have it hooked up to your stationary bicycle so you can peddle your grain through the mill on brew day.  If anyone else has motorized their mill using a different technique, I’d love to hear about that as well!

1 Comment

Steve Smith

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