Hario Mini Mill Slim – Our Review

The Hario Mini Mill

Note: Hario has since released a newer version of this grinder with multiple improvements over the version we reviewed.

The Mini Mill Slim is Hario’s “easy to use, easy to clean” hand grinder—best for grinding one or two servings of coffee without the noise or expense of a automatic electric burr grinder.

Grinding / How to Use

Using the Mini Mill is simple. Remove the handle and clear plastic cap, then add the beans. I usually add a single scoop for my Aeropress, but weighing the beans will yield a more consistent cup.

Replace the cover and handle, then rotate the handle clockwise to start grinding.

I tend to hold the Hario in my left hand and rotate the handle with my right—though some people say they’re able achieve a more consistent grind by setting the grinder down on a level surface. Test it out and see if the difference makes up for the less comfortable way of grinding.

If you do set the grinder down, be aware that there’s very little traction provided by the hard plastic bottom and the grinder may slip.

You can expect to spend at least two minutes grinding for a single serving of beans, more if you tend to get distracted like I do. Just remember: if the handle’s not turning, you’re not getting any closer to that delicious cup of coffee.

Adjustment

To adjust the coarseness of the grind, a gray, fluted nut at the bottom of the grinding section can be turned in either direction. The handle should be attached and held in a fixed position when you do this. As the nut turns, there is distinct ‘click’ for each setting. Although this limits the amount of control you have when selecting your grind, it prevents the burrs from loosening over time.

The system also makes it easy to consistently set the grind coarseness if you find yourself adjusting or cleaning the grinder often.

Tightening the nut yields a finer grind as the gap between the burrs shrinks, while loosening the nut has the opposite effect.

As the ceramic burrs wear, the nut may need to be tightened to keep the gap consistent—though I’ve avoided the need to do this on the fly by resetting the burr spacing after each cleaning.

Although I don’t use my Hario for coarse, French press grinding, I have read that the grind becomes less consistent as you loosen the adjustment nut. If a coarse grind is something you’re hoping to achieve with the Mini Mill, check out Garret Oden’s post on a simple modification to the Mini Mill that should yield a more even grind.

Construction

The Hario Mini Mill is solidly constructed. The functional pieces are stainless steel and ceramic, while the housing is made of acrylic and polypropylene—both hard plastics.

I’ve never once been worried about causing damage to the Mini Mill with normal use. Nothing seems loose or wobbly.

The most fragile piece of the setup is the set of ceramic burrs. A hard drop could easily chip them. Since the ceramic burrs are what provide the quality grind though, it’s a weak spot that can’t really be avoided.

One issue I have had with this grinder, however, is wear between the handle and the shaft—something that seems to happen when I remove the handle to add beans to the hopper. The nut on my grinder is stripped enough that the handle often slips when I first start to grind. It’s disheartening since removing the handle is a necessary step.

To reduce wear from this particular issue, I now remove the handle by lifting directly from the center cap—that way I’m not putting unnecessary leverage on the nut by grabbing further down the handle.

Maintenance and Cleaning

Maintaining the Mini Mill grinder over the course of its life comes down to regular cleaning.

The plastic hopper can be cleaned with some dish soap and a quick rinse in the sink. Since the inside diameter is small, a brush or folded-up paper towel helps to remove any persistent residue that doesn’t come off with just soap and water. Beans with higher oil content tend to stick to the inside of container more.

Disassembling and cleaning the burrs is simple. Although I’ve read that water will wear the ceramic burrs over time, I’ve used mild soap and warm water to clean mine on multiple occasions and have yet to notice any issues.

Hario’s manual recommends “a weak, neutral detergent” and a thorough rinse. The mill should be completely dry before it’s reassembled.

If you are worried about using water, a dry brush is sufficient to remove remnant grounds but not any oil that’s built up.

Use Cases

Even if you have an electric burr grinder or plan to buy one in the future, a hand grinder is still great to have around. Use it for camping or travel—or to have as a backup.

I’ve really grown to enjoy the process of hand grinding since I purchased this grinder. And although I often prefer the convenience of electric grinding, the Mini Mill still has a place on my counter. It’s perfect for weekend mornings when I’m not in a rush and don’t want to make as much noise.

Summary

The Hario Mini Mill is a nimble burr grinder that is perfect for single cup brewing methods. If you’re looking for a consistent, high-quality grind at a very affordable price point, this solid piece of Japanese-designed equipment will serve you well. The only major complaint I have with this grinder is heavy wear that seems to occur between the handle and the shaft—something that Hario has addressed in their most recent version the Mini Slim Plus.