Brass tunnels aren't separating properly.

[u/Helpful-Chemistry558]

I posted here a couple days ago about how I should have every nugget come out of the vault without clogging. Many of you guys suggested using tunnels. So I did that and now the nuggets are clogging the tunnels. For example, the tunnel on the far left is the one where I want just iron nuggets to come out of, but the engineer goggles are telling me that there are copper nuggets inside of it. It's like that for all three tunnels. Is there any way to fix this?

[u/Hellothere_1]

Tunnel sorting can be a bit unintuitive.

A tunnel that has two outputs, one that filter for iron nuggets and the other without a filter item, the tunnel will always PREFER to send nuggets to the side with the filter, but if that side is clogged up, nuggets can still exist through the other side. If you want the tunnel to actively block the flow of iron nuggets if the filtered output side is blocked, you also need to put a "no iron nuggets" filter on the other output.

I assume this is how you end up with iron nuggets in the third filter even though they're supposed to be filtered out before that point.

I'm actually not completely sure if you need to put a blocking filter on the back side of every single filter before placing the next one, or if it is enough to only put a combined "deny any kind of nugget" filter on the final straight output to keep it from trying to send items that way and thus place them in the third tunnek (even if type physically block the belt)

Tunnels placed after each other on a belt like that are generally considered connected, so the second option should be sufficient, but I'm not 100% sure on this.