MOB FARM / GRINDER
A dark room spawner that spawns hostile mobs in dark platforms, flushes them with water into a central shaft, and drops them to lethal fall height. Produces XP and mob drops passively.
Materials List
Overview: what the Mob Farm / Grinder is and does
A dark room spawner that spawns hostile mobs in dark platforms, flushes them with water into a central shaft, and drops them to lethal fall height. Produces XP and mob drops passively.
As a farm it automates a resource loop — detecting growth or spawns and harvesting them — so the materials accumulate while you are away. It sits at an intermediate level: nothing exotic, but the timing between parts has to be right for it to work smoothly.
It fits in roughly 20W x 20L x 30H minimum and works in Minecraft 1.0+ through to the current 1.21 release.
How it works: the redstone mechanics
Dark spawning platforms let hostile mobs appear, open trapdoors at the edges read as solid to the mobs' pathfinding so they walk straight off, and water channels nudge them into a central shaft. A drop of 23 or more blocks brings them to one hit from death for easy XP and full drops.
The core parts doing the work are building Blocks, water Bucket, hopper, chest, and trapdoor; the remaining materials are structure and wiring that hold those pieces in the right relationship.
Because it is a farm, throughput depends on how often the resource grows or spawns, so leaving it loaded (within render or simulation distance) is what actually fills the chests.
How to build it
- 1Build at Y=200+ for maximum spawn rates (no caves to compete).
- 2Create 4 spawning platforms (at least 8x8 each) in a cross pattern.
- 3Place open trapdoors along the edges (mobs see them as solid, walk off).
- 4Add water channels on each platform that push mobs toward the center shaft.
- 5Build a central drop shaft (23+ blocks tall for lethal fall damage).
- 6At the bottom, place hoppers leading into chests to collect drops.
- 7Light up all surrounding areas within 128 blocks to maximize spawn rates.
- 8AFK at the collection point, mobs spawn, walk off edges, fall, and die.
Uses & applications
- ▸As a farm it automates a resource loop — detecting growth or spawns and harvesting them — so the materials accumulate while you are away.
- ▸Built from 200× building Blocks, 8× water Bucket, 4× hopper, and 2× chest and more, it slots into a survival base as a intermediate-level project.
- ▸Pair it with an automatic storage or sorting system so the harvested items file themselves away.
- ▸Run several copies side by side — most farm designs here are tileable — to multiply output.
Tips & common mistakes
- !Light every cave and surface within a 128-block sphere or competing spawns elsewhere will starve the farm's spawn rate.
- !Test the full cycle in a creative-mode copy first, then rebuild it in survival once you know the timing holds.
- !Remember a powered hopper is locked, not active — keep stray redstone away from the hopper lines unless you deliberately want to gate item flow.
Mob Farm / Grinder FAQ
How do you build a Mob Farm / Grinder in Minecraft?
Build at Y=200+ for maximum spawn rates (no caves to compete). Create 4 spawning platforms (at least 8x8 each) in a cross pattern. The full build takes 6 material types and fits in about 20W x 20L x 30H minimum.
What materials does a Mob Farm / Grinder need?
The main materials are 200× building Blocks, 8× water Bucket, 4× hopper, and 2× chest, plus the remaining structural and wiring blocks.
How hard is the Mob Farm / Grinder to build?
It sits at an intermediate level: nothing exotic, but the timing between parts has to be right for it to work smoothly. It is compatible with Minecraft 1.0+ and later.
How does the Mob Farm / Grinder actually work?
Dark spawning platforms let hostile mobs appear, open trapdoors at the edges read as solid to the mobs' pathfinding so they walk straight off, and water channels nudge them into a central shaft. A drop of 23 or more blocks brings them to one hit from death for easy XP and full drops.
How tall does the drop need to be in a mob farm?
A fall of 23 blocks or more leaves most common hostile mobs at half a heart, so a single punch finishes them while preserving full XP and drops. Shorter drops leave mobs too healthy; much taller drops simply kill them outright and skip the XP.