You need to feed it wiht:
* 5,5 sand
* 1,5 lead
* 3,41 coal
per second and times the amount of modules you've stacked.
DO NOT MESS UP THE RESOURCES!
From left to right - output, sand, lead, coal.
P. s. it is not recommended to stack over 6-7 modules because of the conveyors' speed. And if it doesn't start working immediately - it's fine. The scheme needs around 30-60 seconds to fill up, depending on the amount of stacked modules and the amount of resources