REDSTONEPEDIA › Circuits › Auto-smelters
Auto-smelter: furnaces fed from one input chest and one fuel chest
a double chest of raw iron in 72 min (100% of 8 furnaces) · ~8 stacks of coal · 108 blocks · rests
Smelts a double chest of raw iron (3,456) in 72 minutes with its 8 furnaces: dump the load in its input chest and the coal it needs plus one stack in its fuel chest (432 + 64 for a double chest), and every ingot ends up in its output chest. With the chest empty nothing moves: no clock runs on.
Fuel it with coal or charcoal: other fuels, such as lava buckets or blocks of coal, may be shared out unevenly between the furnaces.
fits in 11×6×4
3 versions, 1 to 16 furnaces
Every size 3
The best design for each size: pick one to see it.
| size | blocks | numbers |
|---|---|---|
| 1 furnace | 4 blocks | 6.0 items a minute per furnace · its first result within 11 s |
| 8 furnaces (this page) | 108 blocks | a double chest of raw iron in 72 min (100% of 8 furnaces) · ~8 stacks of coal · rests |
| 16 furnaces | 221 blocks | a double chest of raw iron in 36 min (100% of 16 furnaces) · ~8 stacks of coal · rests |
Try it
Watch the hoppers carry the items into the top of each furnace and the coal into its side; the results drop into the output chest (the numbers over each container show what it holds).
How this design does it: Eight furnaces fed by one hopper line, each taking exactly one raw ore and one coal every time the line fills up to its last hopper: that hopper's comparator unlocks all the furnace hoppers at once for a moment, so the load and the coal are shared out evenly and nothing runs once the chest is empty.
Build it
Download .litematic Download the design as text
The .litematic opens in Litematica (Minecraft 26.3): every block of the design in one region. The text file is the same build written as plain text, block by block.
After building it, put a double chest at ITEMS (the items to smelt), a chest at FUEL (the coal) and a chest at OUT (the results): none of them is in the download or its block count.
Blocks used: comparator furnace hopper redstone torch redstone wire repeater stone
With blast furnaces, twice as fast on ores and raw metals (they smelt nothing else): Auto-smelter: a double chest of raw iron in 36 min (100% of 8 blast furnaces) · ~8 stacks of coal · 108 blocks · rests.
Fuel it from a farm: Crop farm: fuels ~2,750 items smelted an hour: a double chest of ore every 1.3 h, 95% of an 8-furnace super smelter at full speed · 639 bamboo stalks · 2,492 blocks · ~4,400 iron + 92 slime to build.
Details: how it works, measurements and properties
In depth
spreads the items of its input chest over its furnaces, feeds them coal from its fuel chest and collects every result in its output chest
How to try it
The smelter runs in the view: items to smelt start in the chest tagged ITEMS and coal in the chest tagged FUEL; hoppers carry them into the furnaces, and every result drops into the chest at OUT. The numbers over each container show what it holds; speed it up with the bar's speed dropdown. Drag to look around, pinch or scroll to zoom.
Measurements
| metric | value | what it means |
|---|---|---|
| minutes for a double chest | 72.2 | minutes from a fresh build with a double chest of raw iron (3,456) in its input chest and the coal it needs plus one stack (496, never refilled) in its fuel chest, until the last ingot is in the output chest |
| of the ceiling | 100% (72.0 min: 8 furnaces always busy) | how close it comes to its furnaces' own limit: every furnace busy from the first tick, 10 seconds an item in a furnace, 5 in a blast furnace |
| first ingot | by 17 s | game ticks from loading the chests until the first ingot reaches the output chest |
| spread | 432 each | items each furnace smelted |
| coal left | 64 (64 in the machine) | coal still in the fuel chest and the machine after the double chest is smelted (it started with 496: the 432 the load burns and a stack) |
| at rest | yes | whether the build comes to rest once its work is done (no: it keeps running, like an elevator's clock) |
| hoppers awake | 32 | hoppers left unlocked at rest: each one looks for items every game tick (lag on busy servers) |
| coal needed | 496 (the load's 432 and a stack) | coal the fuel chest must start with for a double chest: the 432 the load burns and one stack, 496 in all (7 to 8 stacks) |
| bill | 240 iron, 1 quartz, 30 redstone | what its blocks cost to craft: iron, quartz, redstone, slime |
Notes from its designer
Eight furnaces fed by one hopper line, each taking exactly one raw ore and one coal every time the line fills up to its last hopper: that hopper's comparator unlocks all the furnace hoppers at once for a moment, so the load and the coal are shared out evenly and nothing runs once the chest is empty. Put a double chest of raw ore and 7–8 stacks of coal in, come back in 72 minutes. Variant: super-smelter-8-blast (blast furnaces: twice as fast, raw ores only).
Properties
| Study | Auto-smelters |
|---|---|
| Kind | Auto-smelter: furnaces fed from one input chest and one fuel chest |
| Blocks placed | 108 (not counting the chests the view adds) |
| Box | 11×6×4 (264 blocks of space) |
| Made of (the blocks that change state) | comparator, furnace, hopper, redstone torch, redstone wire, repeater, stone |
| Inputs / outputs | no input / OUT |
| Flags | several versions of one mechanism |
| Design file | super-smelter-8 |
The design file
Design file (52 lines)
# Auto-smelter: a double chest of raw iron in 72 min (100% of 8 furnaces) · ~8 stacks of coal · 108 blocks · rests # https://vjeux.github.io/redstonepedia/circuits/smelter/super-smelter-8.html name: super-smelter-8 circuit: smelter 8 port items: 0 4 0 port items.b: -1 4 0 port fuel: 0 2 1 port output: 8 -1 0 origin: 0 0 -1 palette: X minecraft:stone r minecraft:redstone_wire K minecraft:comparator[facing=west,mode=compare,powered=false] P minecraft:repeater[delay=2,facing=west,locked=false,powered=false] t minecraft:redstone_torch[lit=true] O minecraft:hopper[enabled=true,facing=east] F minecraft:furnace[facing=north,lit=false] Y minecraft:hopper[enabled=true,facing=north] E minecraft:hopper[enabled=true,facing=down] D minecraft:hopper[enabled=true,facing=down] T minecraft:hopper[enabled=true,facing=east] L minecraft:hopper[enabled=true,facing=east] layer -1: ........... OOOOOOOO... ........... ........... layer 0: ........... FFFFFFFF... YYYYYYYY... XXXXXXXXX.. layer 1: ........... EEEEEEEE... TTTTTTTT... rrrrrrrrrX. layer 2: XXXXXXXX... DDDDDDDDXX. ........... .........rX layer 3: rrrrrrrrXXX LLLLLLLLKPX ..........X ..........r layer 4: ........rrr ..........t ..........r ...........