I have found many commonly available kitchen type processors excellent substitutes and additions to an herbalist's tool chest in performing comminution. You can usually pick up second hand food processors at local garage sales that will slice up soft plant parts very nicely. The tougher parts will need more industrial constructed grinders, like the Vita-mix or Blendtec which usually have a higher price tag, even in the used market. Nevertheless, they can be excellent machines for further processing of raw herbs. In the antique side, one can pick up a number of different types of grinders that will work very efficiently by hand. Various old time coffee grinders and grist mills work quite nicely on very hard, not easily pulverized roots and nuts. Sometimes they can be picked up at flea markets very reasonably.
General Rules for Operating Hand Mills----Much of the dissatisfaction experienced in operating hand mills has arisen from improper methods of using them or from failure to measure accurately the degree of resistance to disintegration possessed by the substance to be ground. One of the first requisites as before mentioned, is to dry the substance as perfectly as its physical character will permit without injuring it. If coarse, bulky, fibrous roots, barks, or similar substances are to be ground; they must first be cut or bruised. Most substances are ground with less labor, if they are first passed through the mill with the coarse adjustment, returning the portion which is sifted out, for regrinding, after setting the plates more closely together. This plan is repeated until the whole is ground. Care should be taken not to feed the substance into the hopper faster than it can be ground. The desire to get through quickly is the most frequent cause of clogging the mill and when this occurs much time is lost and the operator is strongly reminded of the well worn proverb about undue haste. If a considerable quantity is to be ground, two persons can operate the mill to better advantage then one, ---one feeding the mill carefully, the other supplying the physical labor and after the expiration of a given time, exchanging places. Good judgment is necessary in determining the rapidity with which substances can be fed into the hopper. Resinous or oily drugs, or substances which soften by heat, require very careful treatment and cannot be fed rapidly; dry ligneous barks or roots, on the other hand, can be fed as rapidly as the extent of grinding surface of the mill and the muscle of the operator will permit. The mill should be thoroughly cleaned after each operation, particular attention being given to the grinding plates. In the case of substances which form hard lumps by heating or clogging up the plates, the quickest way is to use boiling water to soften or dissolve the lumps; the plates should then be quickly dried, to prevent rusting. By running sawdust, bran, or rice chaff through a mill, after an odorous drug has been ground, it may be speedily cleaned and freed from odor. (Remmington's Practice of Pharmacy, 1926)