648. Grinding, Sifting

Shabbos 8:15

One who grinds in the volume of a dried fig is liable. If a person crushes spices or herbs in a mortar, he performs the labor of grinding, for which he is liable. If one dices a vegetable that has been detached from where it grows, he performs a subordinate labor of grinding. Similarly, if someone saws wood because he wants to use the sawdust, or if he files a piece of metal for the shavings, he is liable in even the slightest amount. One who chops wood is not liable for grinding unless he yields a volume of wood chips sufficient to cook a third of an egg.

Shabbos 8:16

One who sifts in the volume of a dried fig is liable. One who kneads in the volume of a dried fig is liable. One who mixes soil performs a subordinate labor of kneading. The minimum amount for which one would be liable is a volume sufficient to make a goldsmith’s crucible. Mixing cement cannot be done with ash, sand, bran, or similar substances. If a person puts sesame seeds, flax seeds or similar such things into water, he is liable for kneading because they get stuck to one another.