The factory input is train based (except water) using one-headed trains. The factory output is science at a rate of 554.4/min (9.24/s), which is 462/min (7.7/s) of each science pack (double red and green). This rate was chosen because it fits an assembly machine 3 with full productivity and 8 beacons, giving the science pack assembly machines a ratio of 10-12-12-5-7-7.
Since 0.15.27 all science use equal ratios of science packs, making half the red and green assemblers obsolete. The new ratio should be 5-6-12-5-7-7.
After deciding on the bottleneck of 462 science packs/min, the requirements for each recipe were calculated for the remaining products using only paper and a basic calculator (which was part of the fun for me in making this build). The results were compared to production statistics from an old factory with 462/min science packs as its limiting factor. Knowing all required resources and intermediates (assembler outputs), all inputs could be calculated and the minimum needed belts could be found. Finally, and probably most importantly, the minimum required crafting speed could be calculated. It is used to easily find the minimum amount of assembly machines to produce the required output. This is especially handy for the non-intermediate products, that can’t use productivity, and therefore don’t get dedicated beacons. They rely on being placed next to existing beacons and/or use speed modules themselves.
The calculations for oil were more complicated (as always) because of multiple products from refineries and multiple required products for items, and of cause cracking with productivity. The oil products are only used for 4 items when making science (plastic, sulfur, solid fuel, electric engine). With AOP (advanced oil processing) but without cracking, the limiting product is PG (petroleum gas), so there is always enough LO and HO (light- and heavy oil), and some of it will have to be cracked.
To find the required CO (crude oil), all product requirements were converted into PG first. Then the PG to CO ratio with full productivity was found to be 133.185 PG to 100 CO, and the required CO could be calculated. Then it was as simple as putting the CO through AOP, subtract the required HO and crack the rest, subtract the required LO and crack the rest, and check that the resulting PG match the required PG.
I only took screenshots of mining productivity, but it does also work at full capacity with military research and double red/green science pack research.
Train stations and belt saturation
The train stations started out with a belt based side balancer, and a standard 4 lane balancer, but over time (like an hour) the wagons would not be emptied evenly. I feared, that this would cause problems with item deliveries to the assembly machines, and because the assembly machines’ production is so close to the requirement, it would ripple through the entire factory.
The problem was caused by the 4-lane balancer. When the output is uneven like in a factory with inserters, some lanes back up, and the input will become uneven too. My solution to this was to add a load balancer on the output of the chests, and make a simultaneous unloading of the wagons. This setup can deliver 145/s (a little more than 3.5 blue belt) per side with perfect balancing, and the factory needs a maximum of 280/s from one station (7 blue belts exactly). It may look like the stations can’t keep up with demand, but in reality it does works quite well. Without the 4-lane balancer, this station unloading setup can deliver 4 fully saturated blue belts, if the output is even.
When setting up trains, I used the following amount:
- 5 trains each for iron and copper.
- 1 train for steel
- 3 trains for coal
- 2 trains for stone
- 3 trains for crude oil.
As a courtesy to my fellow Factorio players, here are some things, that I didn’t do myself.
- Lane balancers: RedditNamesAreShort / ICantThinkOfABetterUsername
- 8-belt balancer: RubiksImplosion
- Some of the logic for the train stations: MadZuri
- Electronic circuit build: Found in online multiplayer and then modified to fit my needs. It seems to be based on a design by 3f6b7
- Processing unit build: Copy-paste from online multiplayer. I don’t know the original designer.