A food processor's chopping blade throws food outward and cuts it on impact, but the slicing and shredding discs work a completely different way. They hold a raised blade fixed at the disc's edge, and the feed tube's pusher forces food past that edge as the disc spins beneath it. Thickness comes from how far the blade sits proud of the disc surface, not from how hard or how long the machine runs.
Why the discs don't throw food the way the blade does
The chopping blade cuts by throwing food outward against the bowl wall. A slicing or shredding disc works nothing like that. It's a flat plate with one raised blade fixed into a slot near the rim, spinning below a fixed height. The feed tube's pusher shoves food straight down onto that spinning disc, and the blade shears off a slice with every rotation — closer to how a lathe peels a ribbon off a block than how a knife chops. Thickness isn't a function of speed at all. It's set by how far the blade edge sits proud of the disc floor. Swap in a disc with a wider gap and every slice comes out thicker, no matter how fast the motor spins.
Why the shredding holes are actually tiny blades
A shredding disc looks like a colander, but the holes aren't there to sieve anything. Each one has a small blade punched into one edge, angled up into the food's path. As the disc spins, that raised edge slices off a thin strip, and centrifugal force is what flings the strip down and out through the hole into the bowl — not before it's cut. A fine grating disc uses the same idea with more holes packed closer together, each with a smaller blade, which is why it produces sand-sized shreds instead of ribbons. The difference between a coarse and a fine disc isn't the hole diameter. It's how small a blade is punched into it.
Why soft food comes out mangled instead of sliced
Slicing only works if the food holds its shape long enough to meet the blade edge and get sheared cleanly. A carrot or a potato has enough cell-wall rigidity to resist the pusher's pressure for that split second, so the blade cuts through it instead of squashing it. A ripe tomato or a banana doesn't have that rigidity. It collapses under the same pressure before the blade can make a clean pass, so what lands in the bowl is crushed pulp instead of a slice. It isn't a dull blade or the wrong setting. It's food that gives way before it gets cut.
Why how you pack the feed tube changes the slice
The disc only cuts what actually reaches the blade in a controlled way, and packing determines that. Loose pieces tumble as they fall, so each one meets the blade at a slightly different angle and a slightly different moment — which is why a handful of loosely dropped carrots comes out as slices of uneven width. Standing pieces upright and packed snugly against each other holds them in a fixed orientation, so the pusher drives them onto the disc at the same angle and the same steady rate every time. Consistent slices come from consistent contact, not a sharper blade or a slower motor.