Why Doesn't My Mob Farm Work? (Tutorial) | Mastering Minecraft 1.15 (Java Edition)

This is the first in a new tutorial series called Mastering Minecraft where we explore questions about Minecraft. We use science, demonstrations and experiments to show how things work and how to do things your world. Today we look into reasons why your mob farm may not be working or producing the rates you expect. We use my creeper farm as an example mob farm but these discoveries are true for all general mob farms. This series is focused on Java Edition Minecraft 1.15 currently. If you have questions about Minecraft, please post them in the comments below.

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Music:

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[frederikja]

future questions:

bedrock breaking
crop growth (specifically rows, and bee interaction)
passive mob spawning
nether mob spawning
slime chunks, ocean spawning (drowneds, fish and ocean monuments)
villagers
iron golems
snow and ice
tnt duping
item duping

just to name a few, im sure theres plenty more topics aswell

[PeteBurnsBright]

Here are the numbers for each farming condition:

Optimal: 13180/hr (100% efficiency)
Roofless/no pack spawning: 5256 (40%)
At build limit: 1866 (14%)
On ocean, side AFK: 281 (2%)
On ocean, top AFK: 5060 (38%)
1 unlit cave in spawning radius: 6417 (49%)
1 other player elsewhere: 611 (5%)

I think I'll be going with an ocean build for my single-player world. World eating seems like a lot of work to get more gunpowder than I could ever use.

[namorcaz]

Only 65k views? This is the most informative video I have seen regarding Minecraft.

[DoktorSchadenfreude]

This was tremendously helpful. Even though I had read up (and understood in principle) the importance of conditioning my farm, the visual impact really made it clear. Thanks, Logic!

[jonotis]

Thanks, Logic! Clear and straightforward explanation of how hostile mob spawning works. I knew the rules, but a few of the results were shocking. Can't wait to see more in this series!

[necrosapiens]

A well-needed look at some of the common problems players encounter when building farms. I've always enjoyed when people explain design choices in their farms; one of the reasons I originally started following your content.

[krheez]

What if the other player stands in a different "non-spawnable area" like the one you did for your farm. Would that double the output of your farm?

[fivoka]

There's so much to learn about this game, can't wait for upcoming episodes !

[mechatyrants]

Absolutely love this new series. I've used a couple of your farm designs on my survival server and they've always been really good, even without creating perimeters or anything. It's a small server, I wouldn't know what to do with 13k gunpowder per hour. Still, love having a good source for this kind of information instead of trying to remember which psicrafter casually mentioned some critical info in a video about a different farm two years ago.

[Barnabonk]

"Why doesn't my mobfarm work?"
You didn't build the roof and the light level is still >7, mate.

[indianagnomes]

Thanks for doing all the hard work for us and checking out all those different scenarios. It was really helpful. I had used your creeper farm design over an ocean with the spawn point high up, but only made a couple of platforms. I could tell I wasn't getting quite the same spawn rates as your farm but the video really clarified how the rates are affected.

[aadeshsenthilkumar]

So if u want a decent sized farm with no conditioning, then the best is to build it above an ocean and afk up in the sky. (6000 gp/hr is more than enough if your playing on single player)

[homosapien]

Am building a witch farm and I thought it would look interesting if I contoured the terrain around (what was formerly) the witch hut as the R=128 block sphere from my AFK spot above.

I immediately had this question: from where to where is the 128 block radius computed? Is it:
a) from the block I am standing >in< (F3 "Block:")
b) from the block I am standing >on< (F3 "Looking at block:")
c) from the block that my head is in (for line of sight?)

Based on the wiki and other discussions about the requirement of a solid block upon which a mob will spawn, I assume it is from the block I am standing >in< to the block in which (which is the block above the solid block) the mob spawns.

Since 128 is an even number, where is the sphere centered? I have to assume the center of the block that I am standing in.

What about round-off? Does the game round up or down?

Perhaps it would be best if I assumed the worst and made the contour 129 blocks from my AFK spot.

Are my conclusions valid?

[drklynoon]

WOW man that was very informative. Thank you very much.

[garyhunter]

I've been watching a few of your videos just for a creeper farm. Wanted to comment and say your dedication to this is amazing, your knowledge as well really good. I've subscribed keep up the great work

[Jbot]

Thanks for putting those numbers together. I've always built my mobfarms at build height, aware that I wasn't getting the most efficient farm but willing to give up some drops for the convenience. I had no idea that the difference was that much. Subscribed.

[staceyandrews]

I imagine the rates could be even further increase by sending them through nether portals and with the speed that they spawn the portal cache should keep the game from becoming too laggy

[Daethbane]

So amazingly helpful Logic, you learn something new every day! We started a server that had Paper running which was ruining things for our creeper farm so we switched to normal Vanilla with no plugins. Only to still scratch our heads. Now I know it's because we didn't give enough space on the sides of the farm!

[Sebastian-hgxc]

Very helpful. Thanks for the explanations. I found that almost none of the mob farm videos on Youtube contain enough explanation on why things should be done a certain way. It's good to finally be able to understand.

[noammkw]

just wanted to say that i built your creeper farm design 3 times already and all 3 of them work perfectly fine