Your first factory is a mess. That's normal. The inserter grabbing from the furnace is putting iron plates into the gear assembler that's feeding the red science — but the belt looped back and now everything's on the same belt and nothing reaches the lab. Here's a cleaner starting setup.
The Root Cause — Why First Factories Stall
The mistake is building everything in-line. Smelters → belt → assemblers → belt → labs, all in one long chain. One assembler runs out of input and the entire line stops.
The fix is the main bus—a set of parallel belts running through the factory. Each production line pulls what it needs from the bus. For a full breakdown of lane allocation and expansion strategy, see our Main Bus Design Guide. The bus keeps flowing even if individual production lines stall.
Step 1 — Smelting column. Build 24 stone furnaces per ore type (12 each side of a belt). Iron on one belt, copper on another. See our Smelting Ratios Guide for furnace-to-belt matching. Steel needs 5 iron per plate — build a dedicated steel column later.
Step 2 — The bus. Run 4 lanes of iron, 2 lanes of copper, 1 lane of gears, 1 lane of green circuits down the middle of your factory. Leave room to add more lanes.
| Resource | Lanes on bus | Why this many |
|---|---|---|
| Iron plates | 4 | Green circuits + gears + science + ammo |
| Copper plates | 2 | Green circuits + red circuits + science |
| Iron gears | 1 | Inserters + belts + red science |
| Green circuits | 1 | Everything past green science |
Step 3 — Science side-factory. Don't put science assemblers on the bus. Build them on the side, pulling resources from the bus:
- Red science: 5-10 assemblers on the side of the bus
- Green science: separate sub-factory with its own belt/inserter production
- Science packs output to a single belt → labs
The Exact Setup That Works
Furnace area (build first):
- 48 stone furnaces: 24 iron (12 per side), 24 copper (12 per side)
- Output to 4 belts: 2 iron, 2 copper (upgrade to 4 iron lanes later)
Belt balancer (after furnaces):
- A 4-to-4 balancer at the start of the bus
- Keeps all lanes balanced even if some furnaces underproduce
Production off the bus (build in order):
| Off-bus line | What it makes | Resources from bus |
|---|---|---|
| Line 1 | Red science | Iron plates + gears |
| Line 2 | Green circuits | Iron + copper plates (needs its own copper cable first) |
| Line 3 | Mall: belts, inserters, assemblers | Iron + copper + green circuits |
| Line 4 | Green science | Inserters + belts + green circuits |
| Line 5 | Furnace upgrade (steel) | Iron plates (separate column) |
Lab area (at the end of the bus):
- 20 labs in a 2×10 grid
- Feed science from one side
- Use inserters to pass science packs between labs
Where Most Players Mess This Up
No space between bus lanes. The bus needs gaps — 2 tiles between each lane pair. This is where underground belts, splitters, and power poles fit. No gaps means you can't pull from the bus without rebuilding it.
Science on the bus. If your science assemblers output back onto the bus, your labs will pull materials intended for other production. Science output needs its own dedicated belt.
Copper runs out. Green circuits need 3 iron + 1 copper per circuit. At scale, green circuits consume copper faster than anything else. 2 lanes of copper become 1 lane to circuits and 1 lane to everything else. Expand your copper supply early.
What's Next After Red + Green Science
Once red and green are automated, the next milestones:
- Steel production — 5 iron plates per steel -> 4 steel furnaces for every 20 iron furnaces
- Oil processing — plastic + sulfur for blue circuits + military science
- Blue science — needs engines (steel + pipes + gears) and red circuits (green circuits + plastic). Our Oil Processing Guide covers the refinery setup that produces the plastic and sulfur you’ll need.
- Military science — walls + grenades + piercing ammo. Don’t rush this unless biters are pressing. If they are, our Early Game Defense Guide shows how to secure your perimeter.
Each milestone is a new side-factory pulling from the bus. The main bus design means you can build all of them without tearing down what already works.
Community Verification & Resources
- Official Wiki — Tutorial — beginner walkthroughs and progression guides
- Official Factorio Wiki — Main Bus — bus width recommendations and balancer designs
- Reddit — New Player FAQ — community answers to common first-factory problems
- FactorioLab Calculator — plan your factory ratios before building