Freaking spiders. I need a plunger to fix this clog.

[Kalbuck]

Hello! I built a mob trap. It took a while but was totally worth it. I've already recouped the expense of iron, and gotten a few arcane scrolls out of it. It's 15x15, six levels high. It works beautifully, except for the spider spawns. I don't get nearly as many as skellies, zombos and creepers, but enough that I have to kill them manually every once in a while. My kill setup doesn't get them. Each spawn floor looks like this:

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Half slabs on every 3x3 surface. Don't mind the light, it's pitch black in there when all closed off. Each level is identical. The weird non squares on the other end are due to my water flow being inside the 15 block square spawn area. Rather than block over the whole end, I tried to make as many spawn pads as possible and still have vine traps.

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The water flow.

Here's the kill setup (zomg the iron)

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Whoops, I see that I can remove the vine traps on the bottom there. They're a remnant of an early version of the setup. Anyhow, the spiders fit right underneath the saws. I tried previously to put saws every 2 blocks underneath the current ones, but one row back. But they didn't kill a single spider, presumably because the spiders were just out of reach.

So I either have to figure out why I'm still getting spider spawns, or find a solution to kill them that doesn't impede water flaw and doesn't involve me tearing up the whole kill area. I've looked over lots of vMC posts and searched this forum for any possible solutions, but haven't been able to find anything. Any thoughts?

[Stormweaver]

a spider can spawn on a single block, but not if that block is obstructed on any of it's sides.

the little 2x1 platforms without half slabs nearby are where they're spawning.

[Kalbuck]

Oh damn, really? That should be a simple fix!

[Sandrew]

a spider can spawn on a single block, but not if that block is obstructed on any of it's sides.

That's news to me. I figured spiders could only spawn on unobstructed 2*2 areas. The more you know I guess..

[dawnraider]

Spiders actually need a 3x3 of air to spawn, but only a 1x1 to sit on.

[Kalbuck]

Well that seems to have done the trick! Thanks for the lighting fast response Stormweaver :)

Spiders actually need a 3x3 of air to spawn, but only a 1x1 to sit on.

That does fit. There was definitely unobstructed air above the blocks before.

[SterlingRed]

I know you're intending to block spider spawns but if I were you I'd leave them in. String is useful.

The solution to your problem with not killing them would be to put a second row of saws directly under the ones you have already. You're mistake was putting them one block further behind when you tried it. Saws are Marginally smaller than a normal block size so the spiders couldn't really reach the blade. Drops will still fall past a saw blade since it is smaller than a full block.

[TheGatesofLogic]

I know you're intending to block spider spawns but if I were you I'd leave them in. String is useful.

The solution to your problem with not killing them would be to put a second row of saws directly under the ones you have already. You're mistake was putting them one block further behind when you tried it. Saws are Marginally smaller than a normal block size so the spiders couldn't really reach the blade. Drops will still fall past a saw blade since it is smaller than a full block.

^This, and actually the lower row of saws can be evry other block with a siding in between to lower the resource cost since spiders are 2 wide

[eternal8phoenix]

Um....color me noob or whatever, but why do you need string? I find I get enough for bows and fishing rods while wandering around...Am I missing something? I am only in the early game (pre-mob trap) and it'd be nice to know how useful string is before I get it built.

[DaveYanakov]

Add a downward facing saw above the spider clog and your problem will be instantly solved. Buggers love to climb...

[SterlingRed]

Um....color me noob or whatever, but why do you need string? I find I get enough for bows and fishing rods while wandering around...Am I missing something? I am only in the early game (pre-mob trap) and it'd be nice to know how useful string is before I get it built.

Stakes. I use them for aesthetics and for measuring to layout large builds.

[lucazanna]

Try in this way, much more convenient. Of course it is dark when Steve it's not in :)

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[Kalbuck]

I know you're intending to block spider spawns but if I were you I'd leave them in. String is useful.

The solution to your problem with not killing them would be to put a second row of saws directly under the ones you have already. You're mistake was putting them one block further behind when you tried it. Saws are Marginally smaller than a normal block size so the spiders couldn't really reach the blade. Drops will still fall past a saw blade since it is smaller than a full block.

Aha... I suppose I could free up a few spawn pads for spiders and add the second row of saws (every other block). Can always use more string, I suppose! Thanks :)

[jkievlan]

...or find a solution to kill them that doesn't impede water flaw and doesn't involve me tearing up the whole kill area.

Hint: spider's can't drop into a 1-block-wide space; other mobs can, but those mobs are 2 blocks tall so their heads would still be at the level of a saw that was 1 block above the floor.

[dawnraider]

Like has been said before, items can pass between saws and other blocks like so:

[-
[-
_[]

Where [- is a saw pointing right, _ is air or water, and [] is any block. Saws are only 3/4 of a block thick, so xp and items can pass through the gap.

If you have a solid top layer and a bottom layer spaced every other block, and siding in the gaps, that will work without tearing anything out.

[Kalbuck]

Yeah, thanks guys, I have saws under the first row every other block now and it kills them fine. :)