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[Saiko Kila]

Inspired by topic about traps against trapavoids, who also happen to avoid pressure plates, I did some experiment on supports. Basic idea is to use magma to trigger the plate, which makes support tumble. Other idea is not to use plates, when not necessary. And in my layouts they are usually not necessary, because supports tend to be located next to the plates anyway. Supports are buildings, and as buildings they are as resistant to magma as much as they components are. So I checked time it takes to bring supports down and make a cavein. My setup was as this:

Spoiler (click to show/hide)

These are basically "landmines", which are built in my obsidian caster. Whitish tiles next to the ramps are recreated marble floors, remnants of walls used for building traps. Floors to be caved are made of dolomite. Supports are made from nether-cap, diorite, wood (acacia), zinc, dolomite, copper, nickel and tin.  Bolded ones are supposed to survive magma, all others - not so much.

I dropped magma and measured time needed to collapse the support, and to collapse the cave-in which usually happens shortly afterward - one to two frames usually. But tha game doesn't pause for a moment, so we usually see a state of matters a few ticks after the cavein was triggered. I was curious which materials can be used as reasonable timers.

After first couple of runs I changed setup to involve more supports of the same material, and to involve other materials, potentially better materials, namely pewters and lead. Due to some light randomness the exact time of survival differed amongst runs, but it was always very close, and the sequence of materials was generally . So for zinc it could be 182 frames or 187 frames, but not 195, for example, and lead was always before pewters.

Measured times, from magma contact to collapse, were as follows:

Code: [Select]

lead    45
tin     47
pewter  48
zinc    185
wood    335 (wood starts smoking around 100 ticks from contact, it really hinders observations…)
copper  approx. 1300-1400
diorite approx. 1700-1800

Due to expected errors it is possible that all first metals there would melt somewhere between 40 and 50 ticks, though most likely around 45, the same error is for zinc, and for wood it is around 10. Other values are approximate, due to way they were calculated (from video), though the ranges shouldn't be off for more than 10%. Yes, melting diorite or even copper takes more than one in-game day.

As seen the sequence of melting follows two properties: melting temperature and specific heat capacity (called "specific heat" in RAWs). The lower the melting point, the faster the object melts. The lower the specific heat capacity, the faster it gets hotter and eventually melts. The best short fuses are apparently lead, tin and fine pewter. I like zinc too. The sequence follows a sequence of destroying cages in magma - goblins in wooden cages tend to outlive even copper ones (though it isn't a comfortable life) while zinc cages almost explode shortly after submerging. These supports are "dumb" because there's no logic nor sensors, only basic material properties involved.

How good they are in practice? For my traps they are lethally good, not least because I use shaped cave-ins, which kills everything that happens to be in area. Building destroyers usually stand one tile from a door or floodgate, often directly under the support (supports are passable). When using tin or lead, they have around 45 ticks to run, which, with Agility=2000 would mean about 6-8 tiles, and for the average troll it would be around 4-5 tiles. The most agile denizen of Underworld on my map has agility=2000, though even maximum agility doesn't give much more headroom, plus they like to crowd much, which makes them slower. For comparison, time taken from triggering upright spike trap to make it move is 40, and time from triggering a bridge/floodgate to open it is 100. Supports aren't, but are fast enough for many uses. In fact it may be wiser to use zinc, or maybe some alloy or wood, and give enemies more time to fill the corridors-to-be-they-tomb.

Magma tumbled supports have one disadvantage, which is need for magma to stay at they location. With short time "fuses" that's not an issue, but longer time (like stones) would probably need additional measures. Like setting them in a 3x3 trough with ramps, to collect magma, and making them two levels high (or three levels in shaped caveins). To install one support atop another it is required to make a floor on the first one. Or simply putting a constant source of magma, maybe through a diagonal depressurizer, then it tends to stay for a long time. I use them mainly because my mechanics are really busy in other parts of the fortress, but also because they are means of disposal of unwanted metal...

[Urist Da Vinci]

I approve of this science. Also, you just invented a practical use for lead in DF, if we want the fastest response times.

If a cave-in lands on magma, you can get magma mist as a bonus. Did you observe any of that?

[Theifofdreams]

Okay. I see that this is very clever, but how do you plan on bringing the magma into contact with the pillars at the moment you need the collapse, if you're using it as a trap against enemies with trap-avoid that also avoid pressure plates?

[Thatdude]

I think you found weakness number two.
This trap ,while ingenious and I commend you're science, is very situational because the only way I see of triggering this trap is by having a door with magma behind it which the offending building destroyer is baited to break, thus releasing the flow, toppling the support and causing much !!fun!!. Because of the effort you have to go to do this, you might as well have a magma drowning trap for normal enemies and skip on the whole cave-in part.
However, this could be extremely useful against magma-proof, trap avoid, building-destroyer enemies (the circus comes to mind here).

[Theifofdreams]

I'm sorry I got common sense all over your !!fun!! dorf science.
The way I see it though, aside from the obvious magma-proof, trap avoid, building destroyers, it'd be simpler just to hook up a lever somewhere deep in the sub-cockle region of your fort that triggers a while bunch of collapses along a long and winding path, allowing you plenty of time to cave in everything and (hopefully) catch the intended targets. That or, as Thatdude suggested, magma drowning traps.

[Saiko Kila]

I'm sorry I got common sense all over your !!fun!! dorf science.
The way I see it though, aside from the obvious magma-proof, trap avoid, building destroyers, it'd be simpler just to hook up a lever somewhere deep in the sub-cockle region of your fort that triggers a while bunch of collapses along a long and winding path, allowing you plenty of time to cave in everything and (hopefully) catch the intended targets. That or, as Thatdude suggested, magma drowning traps.

I was referring to one of recent topics, about automated traps. I wanted an unattended trap - or more specifically trigger - that's the reason. Partially it was my inability to find an announcement trigger to pause the game after destroying an object. The game doesn't pause, and my forts are busy, I missed info about destroying building many times. This is solely for building destroyers, also rather for magma-proof ones (though many beasts not really protected can survive long enough to be healed after a short contact), and I even made one, where the beasts are expected to come from the magma filled side, you know. The way I build traps for tougher enemies, is that I first close them (or their expected point of entry) with a bridge, then I build traps, then I open the bridge and wait, sometimes long.

And my caveins are rather easy to replace, because they contain permanent bridges. But they don't need to be replaced often in any way.

Also I like to destroy things.

[Oaktree]

One use would be using lead or a similar quick-melt item as a hatch cover (or even floor?) over a planned emergency magma sump or drain.  Magma melts the floor tile and then drains out before it gets far and causes widespread damage.  Can obviously do the same with wood or another material that will burn/melt, but a quicker failing material gets it done faster.