I'm one of the typical intermediate dwarf fortress players that can split seas, raise magma, weaponize NPCs and has no idea how minecarts work or even really their purpose past weaponization, dwarfputing and various exploits, as in the time it takes to set up a track you could have hauled everything from the area with the same dwarves and wheelbarrels.
Check out the wealth of information in
Larix's Minecart Education Thread.
As for, purposes, your mileage may vary, but I frequently use minecarts for:
- Quantum stockpiles (DF would be a near-unplayable mess without these) and item sorting.
- Defense mechanisms of
varying degrees of silliness.
- Speeding up hauling from the inevitable mess in the trap area to sorting and storage areas.
- Magma transport, manual and automated
- Swimming training. (A dwarf riding a minecart in 6/7 water trains swimming, and is hilarious!)
- Timers for bridges/doors/traps for silk farms, danger rooms, etc...
I would like to make a minecart shotgun that would shoot minecarts when a pressure plate is pressed. How would I go about doing this?
Load a minecart up with minecarts, get it going fast. (See Larix's thread or use any of the several minecart shotgun designs on this forum.)
A minecart ejects its contents when it comes to a halt after moving fast enough. There are two common ways to achieve this:
1. Hitting a wall:
[track][hole in the floor][wall]
Travelling left-to-right, a cart flies into the wall, ejects its contents, which teleport one level up, then fly forward at the speed with which the minecart was previously traveling. The minecart falls down into the hole (in 11 ticks? 8?), clearing the path for the next shot.
2. Hitting a stationary minecart.
[track][hole in the floor][stationary minecart][fortification]
This version compacts things down to one z-level. The moving minecart hits the stationary one, stops, ejects contents, and falls as above, but the contents don't get teleported up. Instead, they fly forward past the stationary minecart, through the fortifications, and toward the target. This is preferred by most designers.
My question is this: launching live animals?
Put a cage full of animals in a minecart, and launch the cage, which should be destroyed on impact. There are examples of crocodile-bombs somewhere on the forums. I haven't tried it, though.
Another question I have for people who bring up magma, after learning how to raise magma using minecarts, is it superior in any way to pump stacks?
In general, it doesn't require you to build the pump stack, just to carve ramps, so you don't need the materials, time and power source of a pump stack. Once you can actually build a pump stack, that's better. But minecarts raise enough magma quickly that I frequently don't bother going back to adding the pump stack and move on to other projects.
One special case that 2/7 magma in a minecart inside a second minecart can be carried safely by a dwarf without burning their hands. Hauled to the surface and dumped using track stops, this is a super-easy method of getting magma workshops built anywhere on the map in the first season. All you need is magma-safe minecarts.