A Guide to Cleaning your Grain Mill

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Cleaning your grain mill is one of those things that most of us know we should be doing, but don't do as often as we should (if we do it at all). I know it's something I put off for much longer than I should have as I was intimidated to loosen the screws of my Barley Crusher. I was afraid I'd mess something up or throw it out of calibration, and it would never work correctly again.
Well hopefully this article will dispel some of those fears and show you that cleaning/maintaining your mill is far easier than you think it is.
The first step is to remove the face and rear plates. These come off by removing two simple Phillips-head screws on the front and back. Note that the rear screws are the same ones you loosen to adjust the roller gap. This time, take them all the way off.

With the screws removed, the plate comes right off, allowing you easy access to brush off any grain dust. I use an old toothbrush on mine, but you can use whatever works.

Next you need to remove the hopper. Again, this is held in place simply by a pair of screws. In this case, the screws secure on the inside of the hopper with a nut. Using the appropriately-sized wrench, remove the two screws on either side of the mill body.

With the screws and nuts removed, the hopper easily lifts away from the mill body.

Now you have easy access to the business components of the mill: the rollers themselves. Give them a good scrub to release any caked-on grain dust. This dust buildup impedes the rollers' ability to grab grain and pull it through the mill, leading to frustrating spinning without crushing any grain. Giving the rollers a good scrub will restore the "tooth" to the rollers, restoring them to their full milling potential. I use a wire BBQ brush to scrub mine, and I use the old toothbrush to get the ends where the brush can't reach.

Lastly, you should lubricate the roller bushings. In order to access them, you need to separate the rollers from the end housings. The whole unit is held together by two bolts in the base. Flip the mill over and loosen these bolts with a wrench. Once the bolts are removed, the rollers should easily separate from the mill ends.

Lubricate the roller bushings with just a couple of drops of food-safe oil. I use vegetable oil in a small squeeze bottle.

That's all there is to it! Now you can put everything back together in the reverse order. Make sure you reset your mill gap width to the desired setting. With my Barley Crusher, the factory width setting is indicated by a pair of corresponding marks on the roller adjustment shaft and the mill body itself. I like to tighten the gap to just a hair past the marks, maybe 1/16 of a turn.

I hope this article has helped ease any apprehension you may have had about opening up your mill, and shown you that you can improve your mill's performance by carrying out 15 minutes of easy maintenance. Aim to do this cleaning/lubrication once or twice per year, depending on how often you brew, or whenever you notice your mill failing to "grab" the grain like it used to.
Nice, simple and straightforward. Soon as I get a set of feelers and a good brush I'll be following this up. Haven't yet gotten round to cleaning my mill and probably milled 50-100lbs since I bought it.
The one thing I wish I had paid attention to when buying my grain mill is if the mill had an o-ring connecting the drive roller to the idle roller. My idle roller continuously gets stuck and I have to fiddle with it to get it moving again, after the fact I realize I could have bought one with an o-ring to drive both for $30 bucks more.
@Clarke Those O-rings usually only last 1 or 2 batches before they break off and end up in your mash. If you keep the rollers clean, they should grab the grain, forcing the other roller to turn, just fine.
I spray mine out with 100 psi compressed air after each use and it still looks brand new after milling more than 1000 lbs of grain.
Awesome article. I have the same mill and I've been wanting to get it apart for cleaning. I will be sure to use this as a guide.
I guess I have been milling on borrowed time for the last 15 years with my JS Maltmill as my cleaning procedure during all that time has been to turn it upside down after each use and give it a couple of good whacks to knock off any stray grain dust.
Great writeup. I just bought a second-hand mill cheap because the owner said it was sticking. I will follow this guide.
A Barley Crusher is in my near (I hope!) future... I'll keep this article in mind! I'd also agree with using mineral oil instead of vegetable oil to lubricate...
+1 on the air compressor, you can get a small one cheap on sale, and they have so many uses. Since I got my mill, my efficiency is up dramatically, not to mention paying far less for grains by the bag- the upfront cost and occasional maintenance make it a great tool.
Compressed air prior to each crush. Blast the rollers and you are good to go. I personally would never take a wire brush to the rollers.
I never thought of disassembling mine until it failed. I've always used compressed air until my last brew when the idler roller locked up half way through my grind. It's going to be a part of my regular maintenance from now on.
"Analyze, improvise, adapt and overcome"
My improvised grinder:
You made a good point that you should get the rollers themselves so you can isolate the cleaning. If I had a mill, I would imagine it's important to clean the rollers well so you don't ever have problems. I would also try to find a good millwright maintenance service.
The folks commenting about using compressed air after each use are spot on! I have the same mill pictured here, and after 2 years of not paying attention to it, I saw what I thought was some leftover dark "dust" that I assumed was from my last stout grind - but turned out to be mold! A good shot of high PSI on the rollers and bin after each use is all you need.
Have to say thank you so much for this walk through! I thought my less than year old Hullwrecker was shot. Followed this guide and it is now back to catching and crushing grain like brand new!