Description
Colossal Furnace
An add-on for Jumbo Furnace by Commoble. Build a furnace out of 216 blocks, run it at five tiers (and a secret sixth, Tier 20), and grow its upgrades in its Heart.
- 6×6×6 multiblock. Place 216 Colossal Furnace Blocks as a solid cube and it forms when the last block goes down.
- 512 items at once at Tier 1, up to 1,728 at Tier 5 (all 27 input stacks in one batch), and 8,640 at Tier 20.
- 27 input, 18 fuel and 27 output slots (135 / 90 / 135 at Tier 20, with scroll bars), plus an Upgrade slot and the Heart.
- Hoppers and pipes work on every outside face.
- Upgrades grow. Put one in the Heart and it slowly turns into the next tier while the furnace cooks.
- Its own furnace screen, whose trim changes colour with the tier.
- JEI and EMI info pages for every item, and its own creative tab.
- With XP Works: a built-in Liquid Experience tank that your pipes can drain.
- Every number is configurable.
Building it
1. Fragment Mold (crafting table, reusable):
I S I I = Iron Ingot
S F S S = Smooth Stone
I S I F = Furnace

2. Jumbo Furnace Fragment: in any Jumbo Furnace, smelt 64 Furnaces + 1 Fragment Mold. You get 1 Fragment and the Mold back. Without a Mold, the Jumbo Furnace makes Jumbo Furnaces as usual.

3. Colossal Furnace Blocks: put 8 Fragments in a ring on a crafting table (the furnace shape) to get 8 blocks.

4. Build: place 216 blocks as a solid 6×6×6 cube. Breaking any block gives all 216 back and drops everything inside.
The full furnace costs 13,824 furnaces (110,592 cobblestone). It's an endgame build.
The five tiers
The item in the Upgrade slot sets the tier. An empty slot means Tier 1.
| Tier | Items at once | Cook time | Items per coal | How to get it |
|---|---|---|---|---|
| 1 | 512 | 5 s | 16 | Build the furnace |
| 2 | 768 | 4 s | 24 | Tier 2 Upgrade: smelt 8 Colossal Furnace Blocks + 64 Blaze Rods + 64 Magma Blocks + 1 Fragment Mold in a Jumbo or Colossal Furnace (you get the Mold back) |
| 3 | 1,024 | 3 s | 32 | Grow a Tier 2 Upgrade in the Heart |
| 4 | 1,344 | 2.5 s | 48 | Craft an Unfinished Tier 4 Upgrade, then grow it in the Heart |
| 5 | 1,728 | 2 s | 64 | Craft an Unfinished Tier 5 Upgrade, then grow it in the Heart |
Unfinished Tier 4 Upgrade (crafting table):
N C N N = Netherite Ingot
C U C C = Colossal Furnace Block
N C N U = Tier 3 Upgrade

Unfinished Tier 5 Upgrade (crafting table):
B S B B = Block of Netherite
C U C S = Nether Star
B C B C = Colossal Furnace Block, U = Tier 4 Upgrade

At Tier 3 and Tier 4 you choose: put the upgrade in the Upgrade slot to run the furnace at that tier, or craft it onward toward the next one.
Tier 20
Put a Tier 5 Upgrade in the Upgrade slot and four bonus slots open under the Heart, one per tier: [Tier 2] [Tier 3] [Tier 4] [Tier 5]. Fill all four with finished upgrades and the furnace becomes Tier 20 (1 + 5 + 5 + 4 + 3 + 2 = 20).
| Tier 5 | Tier 20 | |
|---|---|---|
| Input / fuel / output slots | 27 / 18 / 27 | 135 / 90 / 135 |
| Items at once | 1,728 | 8,640 |
| Cook time | 2 s | 2 s |
| Items per coal | 64 | 64 |
| Throughput | 864 / s | 4,320 / s |
- The input, fuel and output grids scroll (mouse wheel or the scroll bars). The screen stays the same size.
- While any bonus slot is filled, the Tier 5 Upgrade is locked in the Upgrade slot.
- Take a bonus upgrade out and the extra slots freeze: their items are kept (not cooked, not reachable by hoppers) until you put it back.
- The Heart grows +1 per item smelted at every tier, so at Tier 20 it grows 5× faster. Overheat at Tier 20 needs all 90 fuel slots stocked.
The Heart
The Heart holds one Tier 2 Upgrade, Unfinished Tier 4 or Unfinished Tier 5 and grows it into the next tier.
- It grows only while the furnace is cooking: +1 for every item smelted.
- Overheat: with the furnace lit and all 18 fuel slots stocked (90 at Tier 20), growth is twice as fast. The firebox glows brighter and the Heart pulses.
- Targets: 100,000 items for Tier 3, 250,000 for Tier 4 and 500,000 for Tier 5.
- Progress is saved on the item. You can take it out, break the furnace or move it to another furnace without losing anything. Hover it to see
Growing: 42,310 / 100,000. - When it reaches the target, it turns into the next upgrade in place, with a burst of flame.
- Each upgrade does one job at a time, so you can run your furnace on one upgrade while you grow another.
Liquid Experience (with XP Works)
Install XP Works (optional) and the furnace gets a built-in Liquid Experience tank. Without XP Works, nothing changes.
- Smelting XP flows into the tank at 20 mB per XP point. A Liquid XP gauge in the furnace screen shows how full it is (hover it for the amount).
- Pipes are the only way out. Connect any fluid pipe to any side of the furnace and pull it out. Nothing can be piped in.
| Tier | 1 | 2 | 3 | 4 | 5 | 20 |
|---|---|---|---|---|---|---|
| Tank size (buckets) | 250 | 500 | 1,000 | 2,000 | 4,000 | 20,000 |
- Tank full? Smelting keeps going and the extra XP is stored the old way (you get it when you take the items out).
- Tier lowered? Nothing is lost. The tank just doesn't fill again until it's below the new size.
- Breaking the furnace releases the tank's XP as XP orbs.
Requirements
- Minecraft 1.21.1 with NeoForge
- Jumbo Furnace 5.0.0.9 or newer (required)
- JEI or EMI (optional, for the info pages)
- XP Works 1.0.0 or newer (optional, for the Liquid Experience tank)
- Install it on both the client and the server.
Config
serverconfig/colossalfurnace-server.toml in your world folder contains each tier's items at once, cook time and items per coal (Tier 20 included), plus the three growth targets, the overheat multiplier and (section xp_tank) the tank size per tier.
Good to know
- The furnace screen is wide. If it doesn't fit on a small window, set GUI Scale to Auto or one step lower.
- The Upgrade slot, the bonus slots and the Heart are hand-filled only. Hoppers and pipes use the input, fuel and output slots.
- Worlds saved with 1.1.0 or newer can't be opened with 1.0.0. Worlds from 1.1.x open fine in 1.2.0.
- Hoppers move about 2.5 items per second, so the higher tiers are meant for pipes or Create funnels.
Modpacks
You're welcome to include Colossal Furnace in any modpack.
Credits
Built on Jumbo Furnace by Commoble. Its smelting engine is reused under the MIT license, and Jumbo Furnace is required to play.



