Item Sorter: Build a 9-Slot Filter in 20 Minutes
An item sorter routes every item type into its own chest automatically. The core is the signal strength trick: a hopper holding 45 items of one type + 1 filter item outputs signal strength 3, which trips a comparator and locks the next hopper only for that item.
Materials (per sorter + 1 shared line)
| Item | Amount (9 slots) |
|---|---|
| Hoppers | 20 |
| Chests | 9 double-chests |
| Comparators | 9 |
| Redstone dust | ~30 |
| Redstone repeaters | 9 |
| Solid blocks | ~60 |
| Item to filter per slot | 1 + filler (44 same items) |
Build steps
- Lay a hopper line along the wall feeding one input chest.
- For each slot: hopper → double chest below, comparator pointing out of the hopper.
- Put 45 identical items + 1 filter item (e.g. 46 iron ingots) in the hopper — this sets the magic strength-3 signal.
- Run a redstone dust line from each comparator back to a repeater, feeding the next hopper’s lock.
- Each comparator’s signal locks the downstream hopper until the slot is full — so only matching items pass.
How the lock works
- Hopper with 46 items = signal strength 3 → comparator stays on.
- On: the redstone line locks the adjacent hopper (hopper locks when powered) → no item enters.
- The moment the filter hopper holds less than 46 (an item fell into the chest), signal drops to 2 → unlock → the matching item falls in and it re-locks.
Troubleshooting
- Items stuck on the line: the main hopper line is too slow — add repeaters with 1-tick delay and keep the line straight.
- Wrong items fall through: your filler isn’t 45 — count exactly 45 + 1 filter item per hopper.
- All chests lock permanently: a comparator signal is bleeding into the main line — separate the redstone lines with a block gap.