Factorio: How to fill belts on-demand?

In Factorio, I have a belt running around countless assembling mashines, carrying all the resources those need. Unfortunately, the belt mostly fills up with one or two resource types, halting all production.

Should I try to limit production rates to desired levels, or should I try to remove unwanted items? Currently the belt circles around, so items remain in the belt until needed.

Solution 1:

You can attach circuit wires to belts. Here's an example of what that looks like:

https://wiki.factorio.com/Belt_transport_system#Circuit_network

That gives you two abilities:

• Enable/disable
• Read belt contents

You can use these to selectively allow items onto the mixed belt when there aren't enough of that item. You can also read the contents of the belt and remove items when there's too much of one item. According to the wiki, a straight belt can hold 8 items (using both sides), so you might have some filter inserters automatically remove some items if there's more than 2 of that item in a given belt section.