Looking After Your Grinder - By Dave Corbey
This article is about burr grinders, not blade grinders
In general there are a few things that are recommended with burr grinders (generally this applies to the more expensive grinders that can be taken apart easily, rather than the cheaper sub £100 grinders).
When adjusting the grind finer, I recommend always doing it with the motor running, this avoids "bean lock", where compressing what's in the burrs causes them to lock up, it also places a lot less strain on the grinder. When going coarser, the grinder need not be running
Find your burr touching point, with an empty grinder by making the grind finer and trying to spin the burrs with your fingers. If you cannot spin the burrs with your fingers (with flat burr grinders only), go progressively finer until you hear the burrs just whisper as they touch. Don't do this with conical burrs! Knowing where the burrs touch, gives you a handy reference point and prevents mistakes later.
If the motor does jam, switch it off immediately, otherwise it acts as a heater, and some grinders have an overheat fuse that melts and needs replacing, by disassembling the grinder! If it does not have an internal fuse, then the windings on the motor melt.
Clean the grinder out reasonably regularly, for home users monthly at most, any more frequently is not usually required. Do it the old fashioned way by taking it apart, use a toothpick, toothbrush, vacuum and alcohol if you have to. I don't recommend rice and personally think commercial grinder cleaning products that you simply grind through are not that great. They are also expensive.
Don't grind flavoured coffee
When you are cleaning check the burrs, if you do have any chips, it's probably worth changing them (it's amazing the effect even a small chip off a burr can have. If they are quite blunt, again it's worth changing them.
Keep a spare set of burrs handy…it's good for comparison and also if you do damage the existing burrs you are not waiting a few days for a new set.
Clean the hopper (if you use one) and the doser (if you have one), regularly. Every month is good for the hopper. Vacuum the doser every day and clean every week. The doser gets a lot more oils, because the coffee is already ground and sits in there. Unlike the burrs which grind regularly, new coffee and oils cleaning off the old.
Look at what you're putting in the grinder. I find the hopper lid being black is great for this, tip the beans into the lid and check them before placing in the grinder. You can sometimes find these chalky white stones which will actually grind, but do blunt the blades, or harder stones/foreign objects that will definitely cause damage. Dry processed coffees tend to be worse in this respect. You may get told that "our coffee doesn't have stones", but it's your grinder isn't it, and sometimes you find a staple, where they have stapled something to the bag, or the rivet part of ring pull from a drinks can. Perhaps a nail (and I don't mean a finger nail) from a bean turner on the drying patio.
Lastly a new grinder…. BEFORE USING, take the burrs apart and check there isn't a screw, or other foreign object in there. I have seen a few grinders with things inside from the factory!