How do I stop my Hario Skerton from squeaking when I grind beans? My Hario Skerton is very new,  and has recently developed a squeak (like scratching a black board,  but less soul piercing)  that is only present when I grind beans. It's irritating,  but also mildly concerning.  Should it be squeaky? And how do I stop it?
It depends on "where" the squeaking is coming from. Two contact points that might squeak are the burrs themselves and the top part of the crank rod. The good news is that the whole thing dis-/re-assembles rather easily, and in fact this is pretty much necessary for changing the coarseness setting. I'd suggest two possibilities based on my own Hario manual grinder. 


If the ceramic burrs are squeaking, try grinding some very dark-roast beans (E.g., French roast), which will have more oils on the surface than lighter-roast beans. Use a setting about as coarse as for drip coffee. This will naturally lubricate the bits that are rubbing together, and should reduce or eliminate the squeaking. I wouldn't recommend putting any (other) oil on the burr mechanism.
If the crank is squeaking, take the top part of the crank apart as you would to change the coarseness setting. Remove the coarseness adjustment nut (looks like a toothed gear) completely. Oil the shaft and the top of the post through which the rod passes, and make sure the oil is well distributed through the parts where the rod contacts. For the oil, I recommend using a food-grade mineral oil that you are comfortable with. Use a very small amount of oil (like a pinhead size drop in total). I wouldn't use a vegetable oil because it could become "gummy" or go rancid, and I wouldn't use anything non food-safe (e.g., not machine oil, not WD-40).