Factorio Forums

What happened: I was trying to build a smart train station in which I can set up whatever I want with a combinator. The station would grab anything it needs and gets rid of stuff that it doesn't need. I use the set filter in filter stack inserters to achieve this.

Problem: When researching inserter stack size bonus inserters can pick up more than one item. However, they will always pick the full load, even if they can't place it. When they then try and place, for example 3 plates of iron into a container that can only hold 2 of them, they will get stuck over the container, holding that one plate of iron until there is room for it.
That is not a problem if the inserter is only supposed to take iron.
However, when loading for example a train with at least two different filters, or multiple trains with different filters from the same initial container, then the stuck inserter is stopping everything. A workaround is to only use one inserter for one type of item, but that limits for example the use of the 'set filter' option for filter inserters, for example in train (un)loading.

What I expect: The inserter grabbing only as much as it can actually fit into the target destination. Or: When the inserter can't get rid of the item in it's hand, it will place them back where they came from. Of course this would only move the problem, as when the inserter can't put it back it will be stuck all the same.

It's actually quite the drawback to the stack size research. And that is supposed to make things better. I'd be glad for a very fast inserter that can only move one item at a time and that I can put a filter on as a temporary measure.

That's by design. Inserters aren't meant to be the end-all smartest thing when it comes to moving items. Additionally it would cause a massive drain on performance for them to check exactly how many they can move before they start moving + it still wouldn't work when you had more than 1 inserter moving the same item.

Use 1 inserter per item type you're moving.

I'll just leave a mod here.

clearly that behavior should be in the base game. it's not 'all smart' if it detects it can't get rid of the item it's holding. There is no way to avoid the issue aside from having one inserter per item unless one can read the train contents by some signal or limit the stack size on an inserter.
Research is supposed to make your stuff better, not worse in certain cases.