I've got a magma pipe that I want to tap and want to know what of the following ways is best to get to it. First off, I plan on tapping into it about 5 levels down from the top of the pipe. Now, if I understand it right, since I'm not using a pump, and it's not pressurized, then if I tap into it 5 levels down and let it fill up a grid of tunnels with magma, and then channel down into that grid from above, it won't rise up through the channels correct?
Secondly, can I just dig straight up to the obsidian wall and smooth it and then carve a fortification out of a diagnol square to give my dwarf a fighting chance to get out, or can you not carve fortifications like that?
If that doesn't work how does the following look? Cross section:
OMMMMM
OMMMMM
.................cXMMMMMM
................. OMMMMMM
Assuming the "." are tunnels above each other, and then a channel is cut out of end of the top tunnel and then I dig out the wall from the pipe... Will the bottom tunnel fill up but the top tunnel won't? I tried looking at the wiki, and that seems like is what will happen, but I want to be sure. I'll throw in a fortification and floodgate before I tap it also so I don't get too many !!dwarves from beasties.
Thanks!