Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Seikatsukan]

So, I solved most of the problems DF threw at me so far, but this one has had me scratching my head for a couple of days now. I set up a 10x10x2 obsidian farm on the surface wanting to train my gem cutters with renewable "stone", routing magma from my volcano-fed moat and water from the nearby river. The area, the tunnels, the floodgates and the aquifer-based water drainage were all set up perfectly. Levers were pulled, and I had the first batch of fresh obsidian ready to be mined.

And then my dwarves (or me, you decide) decided to be stupid. I designated it all for channeling, but after the deed I noticed the obsidian was not being taken from the area, I had a flood of "Urist McHauler cancels Store Item in Stockpile: Item inaccessible" spam, there was a dwarven child standing near the edge of the obsidian farm refusing to path out and starting to dehydrate, and Urist McMiner had "No Job" despite having been given orders to remove the ramps she left after the channeling.

I had to dig out a few walls to rescue the child, who got out on its own as soon as the wall adjacent to where it stood was dug out. In the middle of this, I realized that the ramps that were now accessible from the non-obsidian tiles were being removed normally, while the others not directly adjacent to said tiles were not. The stone still stood there, nobody even tried to haul it.

My guess is that my dwarves are refusing to path over the obsidian floor. Under these conditions, it seems impossible to farm obsidian. So... what did I miss? How do I fix this?

[dexxy]

you could train your gem cutters on green glass?

[Seikatsukan]

Huh... I didn't know that. The Wiki page on gem cutting said nothing about it (it does now). Funny enough, my dwarves can even cut fire clay.

Thanks a lot for the tip/workaround, but I still would like to know why my dwarves have decided that my obsidian farm is inaccessible. Maybe it has something to do with the fact that is an open-pit farm? I filled it with obsidian a second time with the obsidian boulders still inside, tried making the obsidian into stairs instead of channeling, same results. Now I have twice as many rocks to haul lol. By the way, my mining dwarf is able to walk on the uppermost obsidian floor and the resulting stairs, the problem seems to be that no one wants to set foot on the lower level of the magma farm (where the obsidian wall forms). And the miner was also able to get out of the upper level, so it's not an access route problem.

[DTF]

Burrow problems?

[Seikatsukan]

Burrow problems?

Nope, haven't really tried to use burrows yet because I find them sort of confusing and not really necessary, so there are no burrows defined in my fort.

Guess I'll try to carry my obsidian farming operations underground whe I get back home, see if that works. Other than that, I can't imagine what the problem is. I mean, everyone and their dog farms obsidian, this can't be an extremely common problem or I would have found something about it.

[GreatWyrmGold]

You mentioned an aquifer, which gave me an idea. Is the lower area flooded somehow?

[Fancy Admiral]

10 x 10 x 2

I think this might be your problem, depending on your implementation.  If you are using a bridge (or a set of bridges) for keeping the obsidian reagents separate prior to mixing, you want an n x m x 3 farm.  Magma on bottom layer, middle layer intentionally left blank, water on the bridge on the top.  The bridges frequently prevent designations under them from happening, regardless of their state, so the dead space lets normal channelling happen.

If you're not using a bridge in your design, I'ven't a clue.

[Tirion]

Look at the ramps, are they named unusable ramp?

[Seikatsukan]

@GreatWyrmGold & Fancy Admiral: guess it's time I posted some screencraps, so you can better see what my design is. It doesn't involve bridges, only floodgates. Not as efficient, but easier to make for a first-time thing.



The image on the right left is the upper layer. Water comes in from the south, through the 2-wide moat connected to the local river. At the top left is the water draining hole, at the top right is the hole I had to dig to rescue the dehydrated child. You'll also see a completely unrelated murky pool on the right. The red ramps are various access ways I dug trying to get my dwarves to collect the stone.
The central image is the lower level (obsidian boulders not shown). Magma comes in through the eastern 4-wide tunnel. Haulers would come in through leftover ramps after channeling or (as shown in the image) stairs dug into the obsidian.
The image on the right is a view of the immediate upper layer, showing the terrain surrounding the obsidian farm.

You mentioned an aquifer, which gave me an idea. Is the lower area flooded somehow?

The lower area is a non-aquifer sand layer. No water was left when I started digging, so no water-related job cancellations. However, the layer immediately below the bottom layer is an aquifer, can this cause problems?

Look at the ramps, are they named unusable ramp?

I filled the farm a third time to check back on that. They are simply "obsidian Upward Slope", not labeled as unusable. Curiously, the fabricated obsidian walls are labeled as "Warm Rough-hewn Obsidian Wall" despite not being in contact with magma anymore.

[Garath]

from what you described, ramp pathing problems seemed likely, might be a bug though

[Seikatsukan]

So, I'll abandon that obsidian farm for now and build another one, within my walls, still an open pit, but two z-levels higher. This way I'll make sure it's not directly on top of an aquifer layer, and the obsidian layer will be on the same z-level as the ground; I'll make an entire side of it floodgates so when they are open it will be impossible for my dwarves to not find a path to it.

It's going to take a while, since my full lava moat is going to make bringing water in a bit complicated (and it will involve punching holes in floors with cave-ins). On the bright side, I'll also have an open-sky pool for when I decide to teach my dwarves how to swim. I'll report back when I have results.

EDIT: Scratch that, I think it's a bug. I dug another tunnel by my original farm's magma input tunnel, to see if it made any difference. My miner still refused to step on the obsidian floor. But then, when I was about to build a wall to plug that tunnel, I saw "Obsidian" listed in the materials, and I hadn't mined any beforehand... check it out:



I think I accidentally an ugly, ugly bug.

[Azated]

I've had that bug before. Whenever I tried to build a wall or floor with a stone, its distance increased significantly and the wall was never built.

The only solution I've found is to gen a new world.

[Seikatsukan]

So, I've finished building my new quartzite-walled magma+water open air pool (aka obsidian generator) and made my first batch of obsidian. Guess what. My dwarves still refuse to haul the mined stone or otherwise step on the obsidian floor left after mining out the obsidian walls. I still get the weird negative distance whenever a dwarf refuses to haul an obsidian boulder. Putting a roof over the pool did not help.

At least I know now the problem was not caused by my obsidian farm being a single z-level over an aquifer: as soon as I channeled one of the outermost obsidian tiles, the boulder fell to the natural floor underneath and was immediately hauled. Victory! ...Kinda. It's obvious that the problem lies in dwarves refusing to walk on obsidian. I can't believe I'm the first to see this problem, I really doubt it's related to my worldgen and I can't be the only obsidian farmer using 34.11.

Next step: create an artificial floor for my obsidian farm and try again. If the artificial floor is not replaced by an obsidian one, this could be the solution.

[Brandstone]

I think this may be related to how freezing water occasionally does not create a floor above it.

[Seikatsukan]

I think this may be related to how freezing water occasionally does not create a floor above it.

Might be, however in this case the problem seems to be that there is a floor, but dwarves don't recognize it. I've done some more testing, tried to build an artificial floor where the obsidian one used to be, but my dwarves still won't step on it despite it being a regular quartzite block constructed floor; they just build the outer tiles and, since they don't step on them, forget about the rest. To circumvent this, I tried building a bridge, since all of it can be built from the edge, and succeeded. However, despite there being a perfect, clear and simple non-obsidian path through the lower lever of the pool, dwarves still refused to walk through it. Evidently, the game is doing something to tiles where obsidian has been created that messes with the pathfinding algorithm.

Well, anyway, I thought "Doesn't matter, I'll just cast some obsidian on top of this bridge. Then I can retract it and mine the obsidian, which will fall down, rinse and repeat". As I was casting the obsidian, the 9x9 bridge collapsed in my largest cave-in yet. So very lucky no dwarf was harmed except for some choking on dust, but now I've got an even bigger mess to clean up. I didn't know bridges could collapse like that, I mean, it was full quartzite blocks, supposed to be magma-safe. This game is messing with my obsidian fetish big time.