Hario Mini Mill Mod: A More Consistent Grind By Using Duct Tape!

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If you own the Hario Mini Mill, I’m sure you’ve discovered that the consistency of the grind could be a little better. Don’t get me wrong, I love this pocket-sized grinder but there’s one problem, the coarse grinds are more often than not fairly inconsistent and many of the coffee grounds are different uneven sizes.

I can forgive Hario for a few inconsistencies in the grind, after all, the Mini Mill isn’t going to compete with a large electric commercial-grade grinder which costs five times the price. And, to be honest for the price of the Hario Mini Mill you really can’t complain.

However, all is not lost. After fiddling around with my Mini Mill I have pinpointed where the problem lies with the inconsistent grind and all that’s needed to fix the issue is a piece of Duct tape like this from Amazon.

I kid you not. A few strips of Duct tape and your “modded” Mini Mill grinder will perform a hell of a lot better and you’ll see a noticeable difference in the quality of your ground coffee. I have seen this hack done with regular Scotch tape (1) but in my opinion, after testing the two, the Duct tape works a lot better due to being slightly more spongy and soft.

The problem comes down to two pieces, the outer burr, and the internal metal axle. Both parts tend to wiggle and aren’t set firmly in place. Maybe this is a design flaw, or it was intentional – that I don’t know. But, it’s this wiggle that ultimately gives you unevenly ground coffee.

Hario Mini Mill Mod

So do you want a more consistent, even coffee grind? Keep on reading and I’ll show you how to do this Hario Mini Mill mod with your grinder – trust me it’s worth doing, and the proof is in the below images.

Disassemble Your Hario Mini Mill

To apply the Duct tape you’ll first need to carefully dismantle your Mini Mill Grinder. The first time you do this I suggest that you lay the pieces out in the exact order you removed them so you can easily remember how to put everything back together again.

Hario Mini Mill grinder parts and pieces

Modifying The Center Metal Rod

Now you have everything laid out in front of you pick up the long metal rod and the large ceramic ring (the outer burr), these are the only two pieces you will need. At the end of the metal rod you’ll notice two small raised areas; just above those is where you need to apply the Duct tape.

the outer burr and the internal metal axle

The amount of Duct tape varies depending on how loose your metal rod is, but I used two layers (wrap around 2x). You may find that you will struggle to push the metal rod back through the grinder when you come to put everything back in place.

If you find that’s the case, I suggest that you add the Duct tape to the metal rod once you have inserted it back inside the grinder. Doing it this way can be fiddly, but it’s doable.

Modifying The Center Metal Rod

The Outer Burr Mod

The last modification on the Mini Mill is on the outer Burr. Again, use a piece of Duct tape which is long enough to wrap fully around the Burr (you might have to cut the tape lengthways to get the right length). Once you have applied the tape, place the burr back into the grinder and fix and tighten everything else into place.

The Outer Burr Mod

You should notice almost immediately that there is far less play and wiggle in both the grinding burr mechanism and the metal center rod. If there’s still a slight bit of wiggle you can apply more Duct tape. This is a modification, after all, nothing is set in stone, so feel free to experiment.

Haio burr wheels with tape

You have done the Hario Mini Mill mod!

You’ll quickly notice that your grounds are much more evenly ground and consistent, especially when you’re grinding coarse grounds (10+ clicks).

If you still don’t believe this modification works, I have done a side-by-side comparison of the coffee ground using the Hario Grinder mod and coffee ground without the mod – I’ll let you decide.

Hario Mini Mill Mod Coffee Grind Comparison

“The proof is in the pudding” as they say, so here you are. I’ve ground the coffee using three grind settings: fine (5 clicks), medium (10 clicks), and coarse (15 clicks).

If you’re new to using the Hario Mini, this might sound a little confusing, but trust me it really isn’t. Here’s an overview of how to adjust your Hario Mini Mill.

First, you need to screw the nut all the way down, but don’t over tighten it; the burrs should be flat and flush. Your grinder is now set at click zero.

Turning the nut counterclockwise from this position and listening for a click is how you can adjust the grind setting on the Hario Mini. It will make more sense when you see the below pictures.

5 Clicks

Hario mini mill grind at 5 clicks

At 5 clicks and with the burrs still fairly tight there isn’t much wiggle room even without the mod, and I expected that – but I thought it would be interesting to see if there was any difference. Remember, it needs this modification more in the coarse grind settings where the burrs are opened much more.

However, surprisingly, there seems to be a slight improvement even in this setting?

10 Clicks

Hario mini mill grind at 10 clicks

10 clicks or a medium setting is where the modification is showing some positive results. At 10 clicks the burrs without the mod have a bit of wiggle which allows for uneven grounds. However, using the Duct tape the wiggle is almost completely removed which, in turn, results with a more even and consistent grind.

15 Clicks

Hario-mini mill grind at 15 clicks

At 15 clicks is where the Hario grinder mod truly shines. Without the modification, your grinder is guaranteed to spit out fines and boulders of all shapes and sizes. With the modification, this coarse setting is usable, perfect for the French Press Brewer.

(1) Reddit /r/Coffee/. https://www.reddit.com/r/Coffee/comments/4zcnn4/uneven_grinds_from_hario_mini_mill/

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