# Factorio: How to Build a Building Train, Part 2 of 2

KatherineOfSky has over 2,000 hours in Factorio and has published many video guides, Let's Plays, and tutorials for the game on YouTube.

## Welcome!

Welcome to Part 2 of my Building Train Guide! Please make sure you have read and followed the steps in Part 1. Click the link below to get there!

## Setting up the Destination Station

Setting up the destination station requires some circuitry, but I will explain each step so that you can easily set it up yourself. Read the instructions for the circuit connections carefully and set it up EXACTLY as specified.

If you are unsure, check with the screenshot provided.

1. Make sure you have the blueprint you made in Part 1 of this tutorial. Go to your outpost destination and place the blueprint with the constant combinators and put powerpoles on the opposite side of the track.

2. Next, place down 6 (purple) Filter Inserters to the left of the combinator. (Do NOT use Stack Filter Inserters*). Make sure they face away from the train.

* The reason for using Filter Inserters instead of Stack Filter Inserters is because they have more filter slots and can grab a wider variety of items from the train. The Stack Filter Inserter has only one filter slot, so it will be stuck on one item until it is filled. (If your train doesn't happen to have that item, the inserter won't "look" for others).

3. Connect the inserters together with Red Wire and also connect it to the Constant Combinator. Do not connect it to the next combinator.

4. Click on one of the inserters, and choose "Set Filters". Exit the window, and copy and paste that setting through the whole line of inserters. Use Shift + Right Click to Copy, and Shift + Left Click to Paste. You'll see the filters pop up as you paste to each inserter.

5. Place a row of (red) Passive Provider Chests behind the inserters. Connect the chests together with Red Wire. (Do not connect the inserters to the chests).

6. Place an Arithmetic Combinator next to the other combinator, facing upward (for simplicity). Connect the Red Wire from the chests to the Input side of the combinator (the bottom part/the In arrow).

7. Connect the Output side of the Arithmetic Combinator to the Constant Combinator with Red Wire.

Scroll to Continue

8. Connect the Output side of the Arithmetic Combinator to the Constant Combinator and the power pole with Green Wire.

9. Set up the Arithmetic Combinator as follows: Input: Yellow Each sign * (multiply) -1, Output: Yellow Each sign

10. Make sure that you still have a blueprint of the original combinators. Copy and paste everything for each of the wagons of the train. Note that a simple copy and paste changes the combinators to the first one's settings. However, that is easily fixed by re-blueprinting the initial blueprint.

Make sure you connect the green wired entities to the power poles!

11. For the Bot Wagon, you only need four chests. (If you copied straight over, delete two and their corresponding inserters). Place Filter Inserters below the chests, and a Roboport below that. Set the new row of Filter Inserters to move only Construction and Logistics bots. Connect the roboport to the Input of the Arithmetic Combinator with Red Wire.

12. For the Trash Wagon, place two (yellow) Storage Chests and two stack inserters to feed into the train. Connect both chests with green wire and to a power pole.

13. With Green Wire, connect the power poles together and to the Train Stop.

14. Setup the Train Stop as follows: Mode of Operation: Enable/Disable; Enabled condition: (green) Anything sign > 0.

15. Copy the entire station into a blueprint for use in other areas.

16. Open each of the constant combinators and delete items from the list or change the quantities you want for the outpost.

Note that the Storage Chests need to be the only ones in that network or items are likely to languish elsewhere and will not be returned to the base.

## How it All Works

What we are doing with this setup is as follows: the constant combinator is our requests list. When we connect the inserters together and to the combinator, we are telling the inserters to take specific items from the train based on the combinator's settings. (The filters on the inserters make sure that we don't grab random items).

As the items are being unloaded, the boxes store them and output the number and type to the Arithmetic Combinator. That combinator multiples each value by -1, then passes that signal back to the Constant Combinator, adding the values together. The signal is then routed back through the Inserters, and when the number of a specific item reaches zero or less, the inserter will drop that filter setting since no more are needed. These signals keep circling around until the combinator requests are satisfied, and the inserters stop.

The train stop itself is set to stay open as long as there are requests for items, represented by a positive number. If the power poles are showing all negative numbers, the train stop will disable itself, and the station will be passed over on the train's schedule. This allows you to have many stations being serviced by one building train since they will effectively drop off the list as they are satisfied. This also means that you can expand outposts and gain more materials, or remove outposts remotely since all the components will end up in the trash wagon and come back to the base.

As to the train setup, a simple "5 Seconds of Inactivity" is sufficient to keep it running from stop to stop.

## All Aboard!

I hope you've found this tutorial informative and interesting. Are there other topics you'd like to see me cover? Let me know in the comments! If you have questions or want to meet other Factorians, please come on over to our discord server!