Hario MSS-1B Coffee Grinder - Low-tech Power Drill Conversion

One thing every Dynamics CRM developer needs is good coffee. That's why I've got the Hario MSS-1B Coffee Grinder.

The Problem

Since I got mine, the end of the shaft where the handle attaches has become rounded off. For a while the only problem was that it made the handle difficult to remove, but it is now so bad that the handle just spins without turning the shaft. Since it was already broken, I had nothing to lose by trying to convert it to 'electric power'.

Purchasable Products

When I made the conversion I couldn't find anyone online selling anything useful, but now I'm writing this post I've found a couple of products you could buy. They're nearly as expensive as buying a new grinder, so I'm not convinced. Here they are anyway in case you find them useful:


The low-tech method is very simple. It's based on the fact that, by definition (because it got rounded by the handle), the shaft is made from quite a soft metal.

  1. Find a 'socket' of a similar size to the shaft. I used a 6mm socket (ΒΌ inch drive) that I took from my socket set. The socket has to be small enough to go through the hole in the lid, because once you've attached it to the shaft it's not going to be easy to remove.
  2. Dismantle the grinder so that you can remove the shaft. You must remove the shaft from the burrs to avoid the risk of breaking them in the next step.
  3. Attach the socket to the shaft by giving it a few gentle taps with a hammer.
    A few taps with a hammer
    • I didn't need to hit it very hard, so go easy or you might bend the shaft.
    • Try to get the socket on as straight as possible otherwise it will wobble when you grind.

The Result

Now I can drive the grinder with anything that has a 1/4 inch square adapter.

Power screwdriver

I first tried with a power screwdriver. It turns at just the right speed, but it doesn't have enough torque to keep the grinder turning.

Power Drill

Then I tried my power drill. It is 600 watts, so has no problem turning the grinder. It does require care to avoid turning the grinder too quickly. At its lowest speed it's a little too fast so I suspect that the grinder won't last too long, but it was broken anyway, so I've got nothing to lose.


I've got a couple of reservations about how this turned out:

  1. As I mentioned above, I'm pretty sure this is going to reduce the life of the grinder because of turning it too fast.
  2. The amount of effort in holding the grinder and drill is nearly as much as grinding it by hand. If you wanted to do the conversion as a labour saving measure then I wouldn't bother.