You thought magma cannons were dead after the .31 update? Well it is a LOT harder due to the caverns and the distance, but with the large amount of magma in the magma sea, much more rewarding. Actually, even that wasn't enough for me, it runs out of magma too quickly. I had to build two magma holding tanks near the surface. All told, it uses about 60500 units of power. This is provided by a huge number of waterwheels. I used an exploit where any body of water that flows off the map is permanently marked as moving to make them work - no pumps or maintenance required.
To fire the cannon, pull the lever marked "Magma Lift Power" in the dinning room at hotkey F4. This will pump magma from the magma sea onto the surface. Or, if the firing doors are closed (see next paragraph), this magma will be pumped into the holding tanks. Then pull the lever marked "Pump From Magma Tanks" (be sure not to pump from the magma tanks if you wish to refill them). This will pump magma out of the tanks and into the magma lift pumps. The magma exits from a 3x3 hole just in front of the entrance at F1.
The level of magma can be controlled by 3 levers at the bottom left of the dinning room. It's not set to pump anywhere in the save file, be sure to pick one lever. Be warned that at the highest setting, some of the towers will over top. The magma won't get in the fort (hopefully!), but keep this in mind. If nothing happens, try the lever marked "Unstick Magma Cannon Flow".
You may notice the ground outside is rather barren. This is because this world was generated before the plants rewrite, and the generic grass all got burned up and doesn't seem to regrow (but trees and bushes don't grow back too?). I think this gives the fort a nice lava burned wasteland look
. You may also notice this fort is running fortress defense mod, and some races that should be ambush only (such as hellfire imps and great fiend spiders) will siege you. I assume that this is because the fort's astronomical created wealth (from the pumps with high quality steel parts, high quality construction, and high quality design) is bugging out the arrival conditions
.
(I did use dfhack a bit, such as to help dig out the magma holding tanks. They originally were filled with down and up-down stairs since I had mined for metals here and didn't want to cause cave-ins. The magma moving over the stairs caused epic amounts of lag when I tried to fill the tanks. So I modified dfderamp to turn stairs with a channel designation into empty space. The bottoms of the tanks were manually de-staired and smoothed.)
The save:
http://dffd.wimbli.com/file.php?id=5263edit: Uploaded a movie, because watching everything in real time sure beats watching it at 0 fps. In this case, an elven caravan is the target. As is the rest of the map.
http://mkv25.net/dfma/movie-2400-byebyemerchants