Factorio Forums

TL;DR

Implement true flipping behavior for inserters and buildings with a direct output to allow flipping them without risk of breaking functionality.

What?

Allow inserters and buildings with a direct output (mining drills, recyclers etc.) to choose whether they drop items on the left or right side (not close-far, just left-right) so that they can be correctly mirrored when flipped.

By default, the current behavior can be preserved, whereas the override may only get auto-enabled and configured appropriately when placing a larger selection which includes a building that drops items on a belt facing towards or away from it which does not terminate in the side of another belt.

Alternatively

If a functionality change is not deemed appropriate, add auto-detection with some sort of warning for the problematic setups, to inform the player that they may unexpectedly break.

Why?

The current behavior causes certain setups to break when flipped, which means that the flipping operation is not fully reliable. As far as I've found, this is the only such case in the game - all other cases where a configuration cannot preserve its behavior with a perfectly mirrored layout when flipped seem to be blocked, e.g. blueprints with train stops can't be flipped.

A "flipped" inserter or output of a building is effectively unchanged or rotated 180°, which means that flipping a blueprint which relies on dropping items on a specific side of a belt oriented towards or away the inserter or building doesn't correctly switch the side on which the items are dropped, breaking the setup.

MKMoose wrote: Fri May 29, 2026 10:54 am

What?

Allow inserters and buildings with a direct output (mining drills, recyclers etc.) to choose whether they drop items on the left or right side (not close-far, just left-right) so that they can be correctly mirrored when flipped.

Feature (partially) exists in Modding API: the inserter_drop_position can be specified with sub-tile resolution. Several mods exist to integrate a GUI which allows you to pick the far/near or left/right lane, as required. These changes are preserved regardless of using Flip or Rotate.

Good Luck!

IMO warning would be nice.

Recently I spent almost 1h building the base while hoping for my Green Science factory to produce something, but I didn't notice my flipped BP fucked the line with inserters.

Now that https://www.factorio.com/blog/post/fff-442 is out, i will consider this as implemented.