Take the C40 apart dry, brush the burrs and the grind chamber clear of coffee dust, and put it back together in the same order. Keep the bearings and axle dry. Water and dishwashers are what shorten a hand grinder's life — coffee oils really aren't.
How often does a C40 actually need cleaning?
Less often than you might fear. The NITRO BLADE® burr surface is highly inert, which means coffee oils don't build up on it the way they do on softer steels. There is no need to clean between brews, and no need to run cleaning tablets through it.
As a rule of thumb: once a week if you're grinding every day, once a month if you're a weekend brewer. Beyond that, use a clean bean jar for each dose and you've solved most of the freshness problem already.
And do keep it in proportion. If you're anxious about the cleanliness of your equipment you'll enjoy the coffee less, which rather misses the point.
Before you start: the three screws
Do not unscrew the three mounting screws around the burr on the base of the grinder. These hold the outer burr ring in precise alignment with the axle, and they were set by hand during assembly. Loosening them will throw off the calibration of your grinder and will void your warranty. Everything you need for cleaning comes apart without touching them.
Taking it apart
- 1. Knob. The wooden knob attaches to the crank with a push-button closure. Pull it straight off.
- Crank. The crank is held to the axle by a small magnet. Hold it near the lid and pull it away from the body.
- Grind setting dial. Unscrew the three-pointed dial all the way off the axle. Keep a hand on the dial and the burr as it comes free — there are small parts inside, and they will find the floor if you let them.
- Cone, spring, washers, axle. These now come out for cleaning. Do this over a table. Work over a flat surface with a coffee tray underneath if you have one. It saves a lot of crawling about.
Cleaning the burrs and the chamber
Brushing is genuinely all this needs. A Long Neck Brush #6 gets into the grind chamber and along the burr ring where fingers won't reach; a Barista Brush #2 handles the body and the wider surfaces.
For coffee dust in the awkward corners, compressed air works, a camera lens blower works, and good old lung power works perfectly well too.
What not to do
- No dishwasher. Over time this damages the ball-bearing cartridges, and on a wooden-bodied grinder it will ruin the veneer.
- Don't soak it. If you do choose to rinse parts with water and a gentle natural detergent, disassemble first and let everything dry completely before reassembly.
- Keep the bearings, axle and spring dry. These are the parts that decide how your grinder feels in ten years' time.
Putting it back together
Reassembly is where people trip up, and it's entirely about the washers.
- Insert the top washer before the axle, with the raised edge facing towards the bearing.
- Attach the crank — it helps hold everything in place while you work.
- Slide the bottom washer onto the axle, again with the raised edge facing the bearing.
- Seat the spring into the cone, then slide the cone back onto the axle.
- Push the cone into the body and screw the grind setting dial back onto the axle.
Then find Click Zero and count back out to your setting. Two minutes, and you're brewing again.
A note on the red O-ring
Older grinders came with a small red O-ring, which sat between the washer and the spring to hold the lower washer in place during disassembly. It was never essential, and it's no longer fitted — we found the grinders worked better without it. If yours doesn't have one, nothing is missing.
Parts worth replacing while it's apart
A strip-down is a good moment to look at the small consumables. Springs, washers and bearings are inexpensive, and a fresh set can make a well-used grinder feel new again.
- Ball bearings, set of two — if the crank feels notchy rather than smooth.
- Spring and bearing spacer washers — cheap insurance, and easy to lose during cleaning.
- Central axle — rarely needed, always available.
The whole range lives in spare parts. We build these grinders to be repaired, not replaced — take good care of what you love, and it will keep making excellent coffee long after most kitchen equipment has been thrown away.
