Please take a look at the image below (click it for full size):


According to mob spawn rules, mobs can't spawn within 24 blocks of a player, which is currently okay, because the first spawn floor is 24+2 blocks above the AFK platform.

However, wiki says that mobs further than 32 blocks from the player don't move, which means they will never fall through the trap doors and so on.

The third biggest issue - The grinder stops working as soon as there are 63 mobs at the bottom of the kill tunnel. This can't be a mob cap, because the grinder is over 130 blocks above ground. What could be the reason?

I would appreciate it if you have any other suggestions. I used this tutorial:

And this image as reference:

enter image description here

  • Is the mob cap for your mob farm is consistent 63 or it sometimes fluctuate? Try to light up nearby caves since It will help spawn more mobs.
    – Angelo
    Commented Dec 15, 2015 at 14:51
  • Caves should not make a difference because mobs can't spawn outside the 128 block range. And the spawner is 130+ blocks above ground. Commented Dec 15, 2015 at 14:56
  • Sorry, I didn't read that part. But is the mob cap consistent?
    – Angelo
    Commented Dec 15, 2015 at 14:58
  • and a question, what version are you currently in?
    – Angelo
    Commented Dec 15, 2015 at 14:59
  • Yes, the mob cap was consistent at 63. Version 1.8.9 (latest) Commented Dec 15, 2015 at 15:09

1 Answer 1


The cap on singleplayer for hostile mobs is 70; this means that all you're really missing are 7 mobs.

An explanation for these mobs is that they're persistent due to having picked up an item, being named, or being bosses, and thus are still on the ground contributing to the mob cap.

If not persistence, the only other thing I could think of it being is that they're getting stuck in the upper part of your mob trap. You should be able to check this by climbing up into the mob spawning area after 63 mobs have spawned, and then fixing the block they're getting stuck on.

  • But that limit doesn't apply to spawners, right? Because I can get 500+ spiders from my spawner. Commented Dec 15, 2015 at 18:43
  • By the way, I'm playing with a friend on my own server, it's not singleplayer. Commented Dec 15, 2015 at 18:52
  • @NikolayDyankov Monster spawners can spawn mobs even after the cap has been met, and the mobs they spawn still contribute to the normal cap. On multiplayer, the cap depends on how many players are online. It'll average out to the same number of mobs per chunk, but one player may have more mobs than another. If your friend is online when you are using the grinder, then it's likely that they have the extra 7 mobs loaded around them (or they've named some mobs or given them items).
    – SirBenet
    Commented Dec 15, 2015 at 19:57
  • This is the reason why you should kill the mobs as fast as posibile if your not using this farm for XP
    – BRHSM
    Commented Dec 17, 2015 at 21:48

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