You know, I’ve never really spent a whole lot of time on Minecraft’s minecarts until pretty recently. It always seemed more effort than it was worth, particularly when I started using mods (which happened within a couple of months of my introduction to Minecraft). Classic Technic/Tekkit included Railcraft, but … I dunno … I just never really got the vision of the mod as a whole, even though I tended (early on) to include it in my own personal modpacks.

But recently (as you may have noticed), I’ve returned to the joy of just plain old vanilla Minecraft (albeit, the newest versions of it). And as I’ve explored the way the base game is constructed more thoroughly, particularly in the realm of automation and Redstone mechanics, what I’ve seen is that minecarts are actually a tremendously fun feature of the game with tremendous potential for automating processes other than “take-stuff-from-here-to-there-repeatedly”.

For example, hopper carts can be used to evenly distribute items and fuel amongst multiple furnaces. Now, before you say anything, I know … I know that there are furnace arrays out there that DON’T use minecarts, only hoppers, and they are very, very fast. I realize that. I’ve used them myself. They work great. They’re also boring when compared with the joy of watching minecarts do all the work.

“But actually, that’s highly inefficient. The most efficient way to …” Stop. I don’t want to be rude, so just … stop. I don’t play Minecraft for efficiency. If I were that concerned about efficiency, why in the world would I be playing a dadgum video game? Surely, there are more productive things to be doing with my time. The glory of Minecraft isn’t efficiency, it’s creativity, the union of function and beauty. Sometimes efficiency can be beautiful. But sometimes it’s just dog ugly, like a federal government building.

It just so happens, though, that I have introduced a bit more efficiency into this furnace array than I have seen in other minecart-based furnace arrays. Typically, a minecart-based furnace array that one might see on YouTube simple has the minecarts going all the time and never stopping. With my furnace array, minecarts only move when there is a need for them to move, which means only when (1) items to be smelted need to be distributed, (2) fuel needs to be distributed, or (3) smelted items need to be collected.

Distributing Items and Fuel Amongst the Furnaces

You can do this a couple of ways. The way that uses the fewest rails is to have the minecart go back and forth rather than in a loop.

For this furnace array, I am using eight furnaces. This design can easily be expanded a lot, perhaps indefinitely.

Hoppers on top of furnaces will direct items into the smelting slot. Rails on these hoppers must not be powered rails, since activated powered rails will prevent the hopper below it from pushing items into the furnace.

One side of this furnace array is simply going to send the hopper cart back. The other side is going to determine whether the hopper cart should go back over the furnaces another time (to continue distributing items) or whether it should return to its default position (where it receives items to distribute). This is done by using a detector rail with an adjacent comparator. When the minecart passes over the detector rail and has items in its inventory, you want the cart to go straight (as will happen in the photo below) so that it will be sent back over the furnaces. If there are no items in the cart’s inventory, then you want it to turn off to the side.

This is a simple setup that determines the direction of the minecart based on whether it has items in its inventory or not. How this is set up precisely depends on direction. In this photo, the line of furnaces (and the longer stretch of rail) goes north-south, with south being on the right of the photo (west is up). Remember that at a t-junction, by default rail will connect to the south or to the east (positive X and Z). With a Redstone signal the t-junction will connect to the north or to the west (negative X and Z). Keep direction in mind when planning this kind of project.

This is a closer look at the way the detector rail system works. Remember, the setup in this photo will work ONLY if what is down in the photo is south or east. The Redstone would have to be a little different if “down” were north or west. To the right in the photo is the direction of the cart’s resting place.

This setup will send a hopper cart back and forth over the furnaces until it is empty, at which point it will return to its resting place to await more items to distribute.

The same setup works to distribute fuel, just with the hoppers pointing into the backs (or fronts) of the furnaces.

At either end of the fuel distribution tracks, I find it necessary to drop the track by a block in order to prevent any unwanted rail connections between the “smelt” and “fuel” tracks. Otherwise, the Redstone and rail setup are exactly the same.

Detector rail and other Redstone is exactly the same for the fuel distribution line. This photo is looking to the southwest.

Dropping Off Items and Fuel All Fancy Like

Obviously, to drop off items and fuel to be distributed you could just manually put them in the minecarts and hit a button to send them off, but where’s the fun in that?

What I have done in my example build is have my distribution minecarts resting below the floor of the “front” of the furnace array. A hopper sits above these minecarts at floor level. The player is intended to place items directly in these hoppers.

The top of the hopper here sits at floor level. This is a simple falling edge circuit that I’ve talked about before that will activate the powered rail on which the hopper cart sits once the hopper empties itself. The last repeater needs to be set on at least 3 ticks (right click twice).

The carts that distribute fuel and items to be smelted rest below the floor.

This is what how I connected my new distribution carts’ resting places to the existing rail systems.

Another look to help you see how everything fits together.

If you do it this way, you can use hopper carts. If, on the other hand, you want to put items in a chest or use some other item transportation or sorting system to send items into this furnace array, you’ll probably need to use chest carts instead of hopper carts. This is because items entering the hoppers one by one move so quickly through the hoppers into hopper carts that the comparators that generate the input for the falling edge detectors fail to register any items within the hoppers and, consequently, fail to send the hopper carts on their way once the hopper is empty.

Collecting Smelted Items

Once items are smelted, they need to be collected, and again we will do this via hopper minecart. If you want your collection cart to move only when there are items to be collected, you must set your furnaces on a line of downward facing hoppers. Smelted items will drop automatically into these hoppers. Next to the outermost two hoppers we need to place comparators, and using Redstone dust and repeaters the signals from these comparators will be used to activate the powered rail on which our collection cart will rest by default. Because we are using a back-and-forth distribution setup, the outer two furnaces in the line are the ones that are most likely to have items if the load of items to be smelted is not a multiple of the number of furnaces.

Okay, let me break that down a little. In my example I have eight furnaces. If I send in a multiple of eight items to be cooked (8, 16, 24, 32, etc.), then all the furnaces will have exactly the same number of items to cook (my total divided by eight, so eight each for a stack of 64 iron ore), and consequently all the furnaces will finish cooking at approximately the same time. But if I send in 9 items or 17 items, then one of the furnaces is going to go through one extra cooking process, right? That furnace will be one of the two outermost furnaces (which one depends on whether the total number of items minus the modulus is an even or odd multiple of the number of furnaces). This is why we use two comparators. If any furnace has extra items, one of the two outermost furnaces will.

Comparators reading the inventories of the hoppers under the outermost furnaces will make sure we always collect all smelted items.

The Redstone signal emitted by these comparators activates the collection cart (another hopper cart). We then want the collection cart to pass under the hoppers, go to a drop off point, and then (once items have been dropped off) return to its resting place to await further instructions. So what we need is to have a rail loop with three sequential destinations. This is pretty easy to pull off.

You can create a circular sequence of destinations like this. Which intersections have to be powered with a Redstone signal depends on which direction the rails are going. Just use some levers and fiddle around with it. In this picture, bottom left is the resting place. Once the button is pressed, a cart will go to the top center station, then the right station, then back to the bottom left and stop.

This is just like the example in the previous picture. The resting place is bottom left, the collection point is up, and the drop off point is right. A hidden lever is powering the top right rail intersection.

In the photo above, I have used a simple hopper drop-off point that I’ve demonstrated in previous posts. A barely visible chest receives the cooked items. This collection system will work until all items have been collected from the furnace array.

And there you have it: a minecart powered furnace array that, rather than having minecarts constantly moving, only sends minecarts when they are needed. Now, there’s all sorts of ways to dress this up and modify it. It isn’t a fixed system that if you move one block here or there it stops working. And like I pointed out above, this kind of thing can be expanded quite a bit. Up to 32 furnaces is easy-peasy with hardly any modifications at all. Beyond that, you will need to start doing some moderate modifications, but nothing serious … nothing you can’t figure out. With all the rail, I don’t really know if this saves much in the way of resources from the strictly hopper based furnace arrays (I do think it saves some), but I find this kind of furnace far more interesting to build and observe in operation.