Piston & Sticky Piston
A piston pushes up to 12 blocks when powered. A sticky piston also pulls one block back when it retracts. Both are the foundation of doors, traps, elevators, and hidden mechanisms.
What does a piston do?
A piston is a block that, when given a redstone signal, shoves out an arm and pushes whatever block is in front of it forward by one space. Cut the power and a regular piston's arm simply pulls back, leaving the pushed block where it landed.
A sticky piston is the same machine with a slime face: when it retracts, it drags the pushed block back with it. That pull-back is what lets you make blocks appear and disappear, which is the heart of doors and hidden builds.
How many blocks can a piston push?
A piston can push a line of up to 12 blocks at once. Try to push a thirteenth and the piston simply refuses to fire. Some blocks can't be moved at all — obsidian, bedrock, anything with a tile-entity like a chest — and certain blocks (like glazed terracotta in some cases) break instead of moving. Slime and honey blocks are special: they drag adjacent blocks along, letting you build flying machines.
Building a piston door
Pair two pistons facing each other across a gap and wire them to a shared input, and you get blocks that slide aside to open a passage and slam back to seal it. The demo below drives a small door from two buttons — tap one to operate it.
Key facts
- Pushes a line of up to 12 blocks; refuses to fire if more would move.
- A sticky piston pulls one block back on retraction; a regular piston leaves it behind.
- Cannot move obsidian, bedrock, or blocks with container/tile-entity data (chests, furnaces).
- Slime and honey blocks drag neighbouring blocks — the basis of flying machines.
- The extended piston arm itself counts as a solid, pushable obstacle.
Bedrock vs. Java: no quasi-connectivity
This is the big one. Bedrock Edition has no quasi-connectivity (the “BUD” quirk where a piston in Java can be powered by a block diagonally above it). On Bedrock a piston fires only when it is actually powered — directly, or through a block touching it. Many Java door designs rely on quasi-connectivity and will not work on Bedrock without redesign. Bedrock pistons also have a fixed start delay of 2 game ticks (0.1s), so the “0-tick” piston tricks that work in Java are not possible on Bedrock. This simulator follows Bedrock rules, so build accordingly.