minecraft-java-edition
I'm working on a large scale mob grinder beneath my server's central area. It's main purpose is to trap monsters away from players. Using the /fill command, I dug a very large cavern 256×256×60 to prevent most uncontrolled spawns.
What is the best design for a mob control/grinder built in this large cave that:
Thanks guys
There are a couple of problems you could be having. As has been stated in comments above, very likely many of the mobs are spawning in other areas. Also, if you have moved up 13 levels you have greatly increased the places where mobs can spawn. If you're on bedrock, the area on the surface (assuming you're under land, and not water) is considerably smaller where mobs can spawn, than if you're up 13-20 more meters.
The second issue, is that mob caps are computed globally on a multiplayer server, so if someone pops up on the server, and starts up a mob grinder, basically all the mobs can be spawning in their areas, and not in yours. You have to out compete them on spawning space. 50x50 may not be very large for a well established server.
Finally, keep in mind that most mobs only move if they are with 32 meters of the player. So, water pads like you have are of limited utility if you are far away:
It is probably not dark enough. Try closing off all entries to the spawners.
Best Answer
If your main purpose is to redirect spawns away from the surface, you don't actually need to kill the mobs. All you would need to do would be to fill the space with spawning pads every three blocks vertically, i.e. divide the cavern vertically into 15 separate spawning rooms (3 blocks for air, 1 block for pad, repeat). This will allow all hostile mobs to spawn, including Endermen.
If you do actually want a system that will also kill the mobs and collect the drops, you will be hard pressed to avoid both water and redstone - you'll need one or the other, or likely some of both, to funnel the mobs to a central killing point. One simple method is to make large pads (10x3 or something like that) and in between them make channels 3 blocks deep and 2-3 blocks wide (at least 2 blocks for spiders). Make water streams through the channels, using the sign and stair trick to achieve constant flow, and lead them to a central point where you kill the mobs automatically by drowning or lava or dropping them or whatever. See picture below.
The slabs in my system prevent spiders spawning, and obviously you'll want a 3 block high ceiling, but otherwise this shows a good method to use. The stairs allow the mobs to be pushed up a block into the higher water stream. In this picture the water flows from left to right in the large channel, and in the small channels it flows towards the big channel. In the central collection point, the tube has alternating water and air blocks, using signs to create the air blocks, allowing the mobs to swim up while not drowning. If you want to move spiders you'll need to use a 2x2 tube and place water in two opposing corners of the tube at one level and the other two corners on the next level, then repeat the pattern.