i had a really strange effect when using this mod (and several other mods) on a longer lastig map, thus i am not entirely sure whether this is only this mod's fault. here is the effect :
since copper ore and scrap copper plates both are smelted to copper plates (with a chance to again get scrap copper plates from this attempt :-), i have a smelter setup that gets fed these two item types (copper ore and copper scrap plates) and at the end of the smelting row a splitter filters copper plates to go ahead and everything else to return to the start of the smelting row and be merged (with priority, to avoid deadlocked belts) to the incoming belt. it runs for quite a while without any problems, but then (suddenly and without any obvious reason, except that it probably only happens when the current type of ore or scrap plates must change because the old type is done, the smelter input is empty, and there is only the other type available on the belt) the last smelter on the line seems to be jammed somehow. when i looked at its details, its window shows that there is nothing in the input slot, and also nothing in the output slot, but only some fuel. although this should indicate that the smelter is ready to take any type of items for smelting, it doesn't get inserted anything.
what is even stranger: to "unjam" the smelter, there are many options, but all of them have one thing in common: something (almost anything!) is done either to the smelter, the inserter or to the belt from which it is fed. for example:
removing some of the fuel, OR adding some fuel, OR inserting any item to smelt, OR changing something on the inserter, OR changing something on the belt (pickup items or add another belt tile after the end of the belt) so that items in front of the inserter change.
the latter probably is also the reason why only the last smelter on a line of smelters jams: as long as the last smelter works, sooner or later items on the belt will move again in front of other assemblers which might temporarily be jammed too but get unjammed when items in front of them move!? only when the last smelter is jammed, the second to last might occasionally jam too, and if those two are jammed also the third, etc. but as soon as the last is unjammed (eg by adding 1 piece of fuel), it will get unjammed and since that causes the belt to move also all others are unjammed.
really strange ... i observed this on a mixed copper ore and copper scrap plates smelting row, and also on a mixed iron ore, iron scrap plates and steel scrap plates smelting row, but never on a mixed copper ore and iron ore smelting row.
ps: at the start of the map i didn't notice such behavior, but in the meantime i have researched a lot and got the inserter bonus. is the inserter maybe waiting for a second item of the same type and gets stuck when it finds only the other type? and thus is unjammed when anything at the smelter, the inserter or the belt changes ?!
but that didn't ever happen to me in vanilla with copper, iron and other mixed types of ore on the same belt.
(and all of this should have nothing to do with jammed smelters that have eg some iron plates to make steel, or one stone to make bricks, and now get only some other types)
