Vanilla Minecraft, no mods, standard (no spawner) mob spawner design. It's not working...

Yes, I am more than 28 blocks away. At the base, I am standing at Y = 78, then on the floor of the mob spawner (where the mobs are meant to spawn) Y = 110.

No I am not on peaceful. I stood at the base of the tower for half an hour on hard and I got nothing.

I am on single player, so any mob restrictions (which I don't think apply anymore in 1.8) are irrelevant

Originally made from cobblestone, with netherrack spawning pads, but I eventually switched that out for cobblestone as well.

What am I doing wrong?

  • 1
    Can you post some screenshots? What is the lighting like? There could be a gap in your transport system, and the mobs are falling through.
    – xornob
    Commented Dec 16, 2014 at 22:41
  • The only thing I can think of are that: Light is somehow getting into the spawn area (the big dark room at the top) or that your floor is unspawnable; made of slabs/ceiling not high enough.
    – aytimothy
    Commented Dec 16, 2014 at 22:50
  • I will add some screeenshots at the earliest convenience, but I assure you, there is no light in the spawning room.
    – Ben
    Commented Dec 16, 2014 at 23:08

1 Answer 1


You are standing 32 blocks away. Mobs spawn when you are at least 24 blocks away, but then despawn over time when they are 32 blocks or more away. The other thing is, you're standing at Y = 78. I'm willing to bet that you're within 128 blocks (spherical) of some caves somewhere, which are likely filling up with mobs (there are thousands of spawning spots in caves vs. likely a few hundred in your mob spawner), and they are keeping mobs from spawning in your trap. Between this and the fact that you are 32 blocks away means it is likely that the few mobs that are spawning could despawn before you have a chance to kill them. Finally, mobs freeze (don't move) when you are around 30 blocks away, so unless your pads are small, the mobs will stop walking before they walk off the edge into your water streams, assuming you're using that style of mob trap. This means they will stand up there till they despawn.

Recommendations: use small (3x3) spawning pads, with water streams in 2-block-deep trenches between them, and make it small enough that the mobs are quickly funneled into your trap before they have a chance to despawn. Etho has a very simple mob trap design that is easy to build, expandable, and efficient, and has remained so since he designed it over 2 years ago. I would stand somewhere at least 24 blocks away horizontally, around midway up the spawner and at least 128 blocks away from any caves that aren't lit up. Since mobs do walk around for a few seconds before freezing, with this mob farm, the mobs are funneled into your trap before they have much chance to despawn, so being over 32 blocks from some pads isn't a problem.

  • Sorry, failed to mention I have zipped around (in spectator mode, so I can see underground) and lit up all surrounding caves
    – Ben
    Commented Dec 16, 2014 at 23:25
  • If that's true, then I'd need to see screenshots to figure out any other problem with the farm. You're sure you've lit all caves within 128 blocks in every direction? That's a lot of caves. Even one or two smallish unlit caves can take a lot of mob spawns away from your farm.
    – Johonn
    Commented Dec 16, 2014 at 23:28
  • Also, I just remembered that I was originally within the 28-32 blocks away range, with little difference. I'll be adding screenshots when I get home :)
    – Ben
    Commented Dec 17, 2014 at 4:25

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