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[Hishan]

An excellent trap idea, water pressure is underused.

Also (correct me if im wrong) but I dont believe that that ice trap would work, as the water rose from beneath it would already be flagged as OUTSIDE beacause you removed the floor to build a grate, and so would freeze in your tunnels. Pumping it in from the side would work however (im fairly sure theres a video of that somewhere).

Thats why I suggested up/down stairs.

You can carve stairs which will keep the area below subterranean, which means the water will remain liquid. Above the stairs is above ground where it will instantly freeze.


It also may be possible to do the exact same sort of trap, only with magma. I haven't tried it personally, but IIRC, it is possible to pressurize magma by moving it through a pump. I haven't verified this though, but thats what the rumor is.

If magma would work, you would instantly cook the entire siege using the exact same trap setup, and it would have the side effect of clearing away all of the junk, leaving only precious bones and goblinite left.

No, I did a 5 minute test, carving stairs DOES keep them subterranean but this is because they dont remove the floor above, making them useless. Please test things before blurting misleading information

[Hyndis]

Water flows along stairs just fine, either carve or constructed.

And yes that is the point to keep the lower portion of the water below ground so it will not freeze. Things also will not path down there because it would always be 7/7 water.

The trap would be 2 levels. The top level is open to the sky, with the floor carved downward stairs. This is where your goblins walk across. They do not walk down the stairs, but you just carve the whole thing as stairs. The level below that is up stairs. This level is flooded. It is also connected to your reservoir that will pressurize the water.

As you never dug out the floor the up stairs level that is 7/7 will never freeze, but the level above it, the one where your goblins and elves are walking, will freeze because it is above ground. Carved stairs are water permeable, but not light permeable.




Alternatively you could use magma. Have a small amount of water, just 3/7. Have magma on the level under the water, keeping it heated and thus liquid. When they're busy wading through the water pull a lever to dump the magma down 1 level, instantly freezing the water into ice, killing them.

[Hishan]

My apologies', I had thought you meant building grates then designates up/down stairs under them would be the solution, but now I see your point more clearly, since i am halfway through my project i will test both designs and compare.

[darkrider2]

hehe, sorry 'bout that. yeah its the subterranean tag that counts. But I guess just mining the entire chamber out can't be that much harder than building it above ground? unless you absolutely have to make it a cryo-freeze trap.

oh wait... yes you do.

[Hishan]

oh wait... yes you do.

DAAAAAAAAAAAAAAAAAAAAAAAAAMN RIGHT

[Hyndis]

hehe, sorry 'bout that. yeah its the subterranean tag that counts. But I guess just mining the entire chamber out can't be that much harder than building it above ground? unless you absolutely have to make it a cryo-freeze trap.

oh wait... yes you do.

Easiest way is to just make a trench. Say you embark on a glacier map, one that is completely flat. What I'd do would be to start the reservoir the Z level below the surface. Pump stack to the top, hope there is an aquifer or some other water source you can tap as it will consume water. (If you are instead using the magma instafreeze method it will actually create water.) Then dig out a trench, I'd say maybe down to the stone. Carve it all the way through the ice, which is a good 4-5 Z levels on many glaciers. Once you hit stone, carve down stairs. Level below that carve up stairs. Link the up stairs level to the reservoir, which is entirely below ground even though it is a higher elevation than the trench.

Water pressure does the rest. You'll of course need some ramps from the surface to your cryo-trench, but thats easy enough.

[expwnent]

Alternatively you could use magma. Have a small amount of water, just 3/7. Have magma on the level under the water, keeping it heated and thus liquid. When they're busy wading through the water pull a lever to dump the magma down 1 level, instantly freezing the water into ice, killing them.

Having experimented with magma and ice, I don't think the magma version of the trap will work. If you melt ice with magma, then take away the magma, it often stays liquid.

But I set up the nonmagma version, and it seems to work fine, at least at first glance.

[Rafal99]

An excellent trap idea, water pressure is underused.

Also (correct me if im wrong) but I dont believe that that ice trap would work, as the water rose from beneath it would already be flagged as OUTSIDE beacause you removed the floor to build a grate, and so would freeze in your tunnels. Pumping it in from the side would work however (im fairly sure theres a video of that somewhere).

Thats why I suggested up/down stairs.

You can carve stairs which will keep the area below subterranean, which means the water will remain liquid. Above the stairs is above ground where it will instantly freeze.

It also may be possible to do the exact same sort of trap, only with magma. I haven't tried it personally, but IIRC, it is possible to pressurize magma by moving it through a pump. I haven't verified this though, but thats what the rumor is.

If magma would work, you would instantly cook the entire siege using the exact same trap setup, and it would have the side effect of clearing away all of the junk, leaving only precious bones and goblinite left.

No, I did a 5 minute test, carving stairs DOES keep them subterranean but this is because they dont remove the floor above, making them useless. Please test things before blurting misleading information

Carve DOWN stairs, I have tested it. They preserve 'underground' state below them, but allow flow of water though them. You carve down stairs in your hallway, dig the area below them so water has access, and make pressure using a high tower with pumps or whatever. You also need to pave the down stairs with floor grates / floor bars so caravan can pass etc.
I was actually going to build freezing trap like that, but got spolied by the upcoming release and are waiting with that project.

[Urist Imiknorris]

This is weird. Way back when I was planning a magma pipe fortress, I had this great idea: I should somehow simulate an eruption in my entrance hall to kill invaders! I still have the basics of the idea, using pumps to pressurize magma to the level of the corridor, and then turning off the trap by simply stopping the pumps. Unfortunately, I have yet to devise a system that will allow the magma to drain from the room.

[Hyndis]

Alternatively you could use magma. Have a small amount of water, just 3/7. Have magma on the level under the water, keeping it heated and thus liquid. When they're busy wading through the water pull a lever to dump the magma down 1 level, instantly freezing the water into ice, killing them.

Having experimented with magma and ice, I don't think the magma version of the trap will work. If you melt ice with magma, then take away the magma, it often stays liquid.

But I set up the nonmagma version, and it seems to work fine, at least at first glance.

The trick is to drop the magma instantly. Like this side view:

Code: [Select]

~~~~~~~~~~  3/7 water
__________  regular floor
mmmmmmmmmmm  magma!
..........  retractable, magma safe bridge
xxxxxxxxxx
xxxxxxxxxx
xxxxxxxxxx  empty chamber to store falling magma
xxxxxxxxxx
xxxxxxxxxx
Side view is not to scale, so its not 1 per Z level, but just to give you the idea of how the trap is supposed to work.

The water is exposed to the freezing air above. It is only kept liquid by magma. Once the heat of the magma is gone due to you pulling the bridge holding the magma against the floor above, there is now nothing heating up the water and so it should freeze.

I have not tried this trap personally, but then I didn't come up with the trap either. I've seen it on a couple fortresses even.

[Hyndis]

This is weird. Way back when I was planning a magma pipe fortress, I had this great idea: I should somehow simulate an eruption in my entrance hall to kill invaders! I still have the basics of the idea, using pumps to pressurize magma to the level of the corridor, and then turning off the trap by simply stopping the pumps. Unfortunately, I have yet to devise a system that will allow the magma to drain from the room.

Pumps on one side of the room, iron grates on the other side? Magma flows across room and things are collected once the magma subsides. There will be time where the room is still unsafe due to 1/7 and 2/7 magma, but it will evaporate.

Use carved fortifications to protect your pumps from building destroyers. If the iron grates get destroyed, no big loss. You wouldn't actually need iron grates anyways. Just a simple pit the magma can fall into will do fine.

Maybe make the iron grate at 1 Z level lower than that, so anything pushed off the edge by the magma can still be recovered. Magma falls through iron grates, and nothing can destroy it because everything that gets pushed off has already taken a magma bath.

[derekiv]

I have plans somewhere for a pressure-based magma trap that shouldn't loose any magma, and doesn't require any bauxite.
(Does magma evaporate when floating on top of a grate over more magma?)
I'll post a scan of my drawing once I get home.

[Hyndis]

Yes, 1/7 magma that is sitting on 7/7 magma will evaporate.

[expwnent]

The trick is to drop the magma instantly. Like this side view:

Code: [Select]

~~~~~~~~~~  3/7 water
__________  regular floor
mmmmmmmmmmm  magma!
..........  retractable, magma safe bridge
xxxxxxxxxx
xxxxxxxxxx
xxxxxxxxxx  empty chamber to store falling magma
xxxxxxxxxx
xxxxxxxxxx
Side view is not to scale, so its not 1 per Z level, but just to give you the idea of how the trap is supposed to work.

The water is exposed to the freezing air above. It is only kept liquid by magma. Once the heat of the magma is gone due to you pulling the bridge holding the magma against the floor above, there is now nothing heating up the water and so it should freeze.

I have not tried this trap personally, but then I didn't come up with the trap either. I've seen it on a couple fortresses even.

Just tried it, and it works beautifully, thanks.

It also works if you have ice right over a magmafall, which can make for a good water source in certain situations.

[Hyndis]

The trick is to drop the magma instantly. Like this side view:

Code: [Select]

~~~~~~~~~~  3/7 water
__________  regular floor
mmmmmmmmmmm  magma!
..........  retractable, magma safe bridge
xxxxxxxxxx
xxxxxxxxxx
xxxxxxxxxx  empty chamber to store falling magma
xxxxxxxxxx
xxxxxxxxxx
Side view is not to scale, so its not 1 per Z level, but just to give you the idea of how the trap is supposed to work.

The water is exposed to the freezing air above. It is only kept liquid by magma. Once the heat of the magma is gone due to you pulling the bridge holding the magma against the floor above, there is now nothing heating up the water and so it should freeze.

I have not tried this trap personally, but then I didn't come up with the trap either. I've seen it on a couple fortresses even.

Just tried it, and it works beautifully, thanks.

It also works if you have ice right over a magmafall, which can make for a good water source in certain situations.

Yup. And then to thaw it out just close the bridge and pump magma back up against the floor, and the ice should melt out so you can collect the goblinite.

IIRC, this should turn your 3/7 water into 7/7 water when it melts, so you would actually be creating water, and then you would need a way to drain off 4/7 water so they can path through it. Needs to be higher than 2/7 or it will evaporate.

But yes, you can exploit this for creating unlimited water if you have access to ice and magma, which should come in handy on a glacier.

You could even use a water pressure cryo trap, using magma to restore your water reservoirs both for drinking water and trap water.