Pepper mill? I don't know if it would work as a cannabis grinder, but most of them have some degree of adjustment. Or a salt mill? I suspect that it takes a lot of toughness to continually grind salt crystals into smaller ones and hold up.
Here's a wiki page about burr mills that might give you some ideas to try:
Burr mill - Wikipedia, the free encyclopedia
I would think that a hand mill/grinder of some sort would be better than ones that are motorized (such as modern coffee grinders). Unless you could slow the motor down greatly.
And for everyone that finds their cannabis grinders - of whatever sort - aren't lasting very long: You are cleaning their working surfaces regularly with something that will act as a solvent such as alcohol, aren't you?
Here's a wiki page about burr mills that might give you some ideas to try:
Burr mill - Wikipedia, the free encyclopedia
I would think that a hand mill/grinder of some sort would be better than ones that are motorized (such as modern coffee grinders). Unless you could slow the motor down greatly.
And for everyone that finds their cannabis grinders - of whatever sort - aren't lasting very long: You are cleaning their working surfaces regularly with something that will act as a solvent such as alcohol, aren't you?