Factorio Forums

Splitters have two inputs, so they can be used to join two belts into one. Unfortunately, they are not guaranteed to pull an equal amount from both belts.

kovarex wrote:Well, currently the priority of joining is not defined explicitely. Sometimes the side that is joined to is always preferred because the side can move, so the items on that side are the first to be picked after free space is created for another item. But it can really depend on the way the items are put on the belt.

I'm moving it to not a bug for now.

Fortunately kovarex is so good, that he got it right one-third of the time anyway! Here are the ways to turn your splitters into balanced joiners.


Double Blue Splitter

Put two express splitters in a row. This is expensive, but it always works.




Double North Splitter, Double West Splitter

Basic and fast splitters are only balanced in two directions. But rotating your belts might be cheaper than buying express splitters.




Same 2x2 Block

We were using double splitters above, because half of them work and half of them don't. You can do some tests to determine which one is joining correctly and remove the other one. But there is a quick way to tell which one is working.

A joiner is only balanced if at least one tile of the joiner is in the same 2x2 block as the output.

Please don't make this like in Minecraft. Please remove this behavior before people start to rely on it and make it impossible to remove it later. The north south quirk was one of this problematic behaviors.

Why would you ever want or need multiple resources equally interspaced on a belt?

xnmo wrote:Why would you ever want or need multiple resources equally interspaced on a belt?

You probably don't, it's just for illustrative purposes. But the same rules apply when it's all the same stuff (say, ore), and in those cases it might matter.

If there was any doubting it before, its certainly gone now. DaveMcW is a boss at this game.

For me and my factories I'm aware of the quirks of joining two belts with a splitter, that is why I never join two belts that have two items on it. I try to only ever join lines that only have the one kind of material on them.

DaveMcW: Nice that you continued the work on this https://forums.factorio.com/forum/vie ... =23&t=5670
Cause I gave up, cause I couldn't find a "rule" with my testdrive (https://forums.factorio.com/forum/vie ... =10#p44394). But I think I have now something to get further.

I have a question. How can someone repeat this? I mean: How did you create your tests? Especially: How did you fill the belts? Everything "by hand"? Cause, when I made some tests with that, it showed up a chaotic result for the joiners sitting not on the same 2x2 block (prefering one side). (again https://forums.factorio.com/forum/vie ... =10#p44394 ). But I must say, that the solution with the double blue belt really behaves like you explained, I never came to the idea to test it with express belts.

xnmo wrote:Why would you ever want or need multiple resources equally interspaced on a belt?

Hehe. This is simple: Cause there is no other way to see, how the items are mixed.
In other words: Copper and iron are only used to see, how the items on the belts are mixed. Take it given, that for the real usage, both inputs have the same item.

This is important. Not very important, but it would be a problem if - as Nova said - this behavior changes in some future version, cause it is quite useful to have an element, which guarantees you a 50% join, or - which is sometimes even more useful - guarantees the preference of one side, cause that allows you to built up storages, which will empty with only one element only, if the storage is needed. See https://forums.factorio.com/wiki/inde ... s/Priority - which is due to these results now obsolete again and needs the third change within 3 weeks.

Dunno about Dave, but I always load my test belts with several chests and fast inserters.

Update for version 0.12.

Splitters now join perfectly in every situation! Hooray!