Mob traps: Mob filtering

[Larmantine]

Recently dug up my old BTW world and got addicted again. I've reached steel already, have a couple of automated farms, decided that I'd should really finally build a legit mob trap. I have the basic structure done, now I'm building the killing part of the trap. I also decided not to discriminate spiders and utilize them as well, I just don't understand how to separate them from the other 2-block-tall mobs. I need this because they all can't share a kill room with chopping blocks and pistons. I tried a to have a 2-wide channel with holes for the other mobs to fall through but they keep swimming up and jamming everything. I seek your advice, guys.

Edit: grammar

[TheGreatIntelligence]

Maybe a water stream going through a one-block tall gap to a separate spider kill chamber?

[Larmantine]

Maybe a water stream going through a one-block tall gap to a separate spider kill chamber?

Thats exactly what I did. But the other mobs won't drop down in the holes before the gap.

[abzu93]

I find that a killing room with a block of 2x2 (4) saws with a two wide stream of water pushing against the lower two much kills everything up to 2x2 in size. It may sound like overkill but nothing escapes.

[Kazuya Mishima]

My last mobtrap also had a saw and chopping block at the terminal end. All mobs would fall into a wide stream of water created by screw pumps and then pistons would push the mobs, along with the artificial water stream, into as single channel where mobs were decapitated killed.

I also had a problem with spiders spawning but i removed some vertical walls a few meters from the bottom and spiders could simply crawl out. You could simply adapt this design and then build an external trap for spiders around the circumference of your existing trap. Now that spiders track chickens you can simply use chickens, isolated in small secure cages, to prompt the movement of spiders to a particular region outside your mob trap and then have the spiders fall on a 2x2 set of saws pointed upward if you have vertical constraints or a fatal drop if you have enough vertical space to permit.

[RalphKastro]

you don't really need the chopping blocks unless you really want the heads.

Edit: how did you manage to get to the end and kill the dragon without a mobtrap?

[dawnraider]

I posted about this a while ago, I built a trap that uses chickens to lure spiders to a separate area. It works very well, just occasionally a normal mob manages to jump across the gap, so just make the wall a half block higher on the other side to make sure only spiders go up. Also, the water falling over saws at the top is not necessary, as spiders don't shoot webs at things they don't have LoS to.

Link: viewtopic.php?f=3&t=7943&p=131299

[FlowerChild]

Edit: how did you manage to get to the end and kill the dragon without a mobtrap?

It's not really a requirement. I don't have one in my current save either, and I'm fully end dimension capable.

[Mason11987]

I see no reason to separate out the mobs. Evering into a 3x2 wide area with water pushing against saw panel saw on the lower level, and panel saw panel above. Kills everything but endermen just fine.

You can also easily incorporate chopping blocks into that design to get the heads you want.

[Larmantine]

how did you manage to get to the end and kill the dragon without a mobtrap?

Why would I need to kill it in the first place? Maybe I've missed something, as I said this save is quite old.

[Larmantine]

Allright, thanks guys. I guess I'll go with dawnraider's design (which looks awesome btw), if I'm up for it, otherwise I'll just have do it without the chopping blocks.