How to build a Minecraft Mob Grinder

A Minecraft mob grinder will gather, trap and kill mobs collecting their drops such as arrows, sulphur and string. This guide will show you step by step, complete with screenshots and interactive floor plan, how to build one.

Update: check out my Minecraft Piston Mob Grinder

How the mob grinder works

The mob grinder is a tower with floors where there is no light so Minecraft mobs such as spiders, zombies, and skeletons will spawn, even in day time. The mobs walk around and drop through holes in the floors. On reaching the first floor, water traps channel them through holes to their fate, a water ride into lava where they die and their drops are collected.

How to build the mob grinder

1. Start by building a base, 23 x 23 blocks. The base dimensions come from the first floor which will be made of:

1 block for the outer wall
2 blocks for the drop hole through which mobs fall
8 blocks for the flowing water which carries mobs to the drop hole
1 block spacer (to separate the next flowing water)
8 blocks for the flowing water which carries mobs to the drop hole
2 blocks for the drop hole through which mobs fall
1 block for the outer wall

Mob Grinder Base

2. Build a water channel. Mobs fall from the first floor through a 2 x 2 hole in each corner. They fall to the ground floor where a 2 wide by 8 long water channel pushes them to their doom. Water flows over 8 blocks and then stops, but items will carry on and fall if there's a drop at the 9th block. Collect and place water using buckets made from iron. Here's 1 of my water channels:

Water Channel

3. Build a lava trap. The mobs are killed using lava. To prevent the stuff they drop being incinerated you use a 'feature' of the game where lava will flow over an empty block if a ladder is placed on an adjoining block. In the screen shot below, see how the lava juts out over the 'empty' block allowing items from the mobs that die to fall. Collect and place lava using buckets made from iron.

Lava Trap

4. Make a water collector. Add another water channel to collect fallen items from the mobs that die like below.

Water Collector

5. Now you'll need to repeat steps 2-4 to build the water channel and lava trap for each corner. Join the wall up around the side and you have built the ground floor of your mob grinder tower. The hardest bit is over.

Ground Floor

6. Build the collecting floor. This floor extends beyond the grinder to allow 4 water channels around each of the 4 corners of the floor below. Mobs on this floor will wander around and eventually end up in the water which will channel them to the corners and down to the ground floor. Note this floor is 2 blocks deep to allow a solid block for the water flow to sit on.

First Floor

7. Build as many other floors as you like. The floors above the 1st floor do not need water channels. They just need to have holes in the floor through which mobs can drop. Mobs will happily drop down holes with a drop of 2 or 3 blocks. DO NOT have any overlapping holes from one floor to another otherwise the mobs will not drop. I've found a checkerboard pattern of 4x4 solid then 4x4 holes very successful giving plenty of space for mobs to spawn as well as a good chance for them to drop to the floor below. If doing this, alternate the solid and holes on each floor so that mobs only have to drop 2 blocks to the floor below. These floors should have 2 blocks high space for mobs to spawn and walk around in. The roof of your top floor must be completely sealed so all floors are dark and mobs can spawn there, even in day time.

Second Floor

Mob Grinder

The completed mob grinder in action! A spider burns to death on the lava. Items dropped by other mobs that have died have been carried by the water channels to the middle.

Mob Grinder Trap

Some final notes:

Mobs will only spawn more than 24 blocks away from you OR 24 blocks away from your spawn point. Don't stand too close to your tower otherwise mobs won't spawn there. Don't build too close to your spawn point either.
More floors means more chances for mobs to spawn so add as many floors as you like.
I built my mob grinder out to sea hoping that mobs would be more likely to spawn in my tower than outside it as there is no land for them to spawn on. I don't know if this is true.
Put torches on your ground floor to stop mobs spawning there. Add a door for easy access.
A ladder up the side of your tower with filled in holes on each floor will provide easy access for maintenance or building more floors.

Have fun!

Tags: Minecraft, mob, grinder, drops, lava, kill, Tower, trap

Comments (58)

29 Dec 2011 11:52 by EZSPECIAL

BananaLife - Any spot within 24 blocks of the player is not eligible for spawning and farther than 144 is too far for mobs to spawn

21 Nov 2011 02:54 by BananaLife

Not sure if any1 still reads this,
but any idea of where or howfar i should put the item pickup, so spiders wont follow you and other mobs still move.

14 Nov 2011 09:48 by Tommy

i made the system better by capping the grinders itself so i capped it at just above the lava the whole way other then where the mob will fall in it works much better now because it now when the mobs die they won't really jump and that saves more items

20 Oct 2011 05:26 by mrweems

Oh god, i was following a different guide before finding this one.

the guide i was using before didn't say anything about the mobs on the Level before the grind.

So they kind of just wander around, and eventually kill themselves.

Might need to think and try and reconfigure if possible for the water channels on the bottom level. Though i've got ten levels up this is going to be a puzzle.

19 Oct 2011 08:07 by ElMarko

I've not noticed them swimming up. Only spiders are a problem. Like always.

17 Oct 2011 02:57 by ElMarko

bobbert I'm fairly sure it's fine in 1.8, mine works beautifully. The only thing climbing the lava is spiders. I'm sure there's a way to separate out just the spiders before the go to the lava, and then send them into a drowing or piston trap instead, but it might required a larger ground floor to accomodate it all. What do you think, Kev?

15 Oct 2011 07:36 by bobbert

This still kills the mobs in 1.8 but they try to swim up the lava now so most drops are destroyed as well in multiplayer

5 Oct 2011 02:05 by Trophic

Notch is taking away endermans ability to pick up blocks, so this will work perfectly ib 1.9

3 Oct 2011 04:17 by derzok

Works in 1.9 - Notch killed endermen's ability to move blocks (certain blocks, at least).

3 Oct 2011 04:08 by Krys

Thanks for the great guide, I'm a new player to minecraft so it's hard getting my head around how everything works heh. I've made mine only a single floor while endermen are on the loose and it seems to be working fairly effectively. I've added cactus in the water to help get rid of spiders, it seems to be working :)

27 Sep 2011 05:18 by Boog

I am totally wowed and preaperd to take the next step now.

26 Sep 2011 03:39 by MadWilliamFlint

I've had some solid successes in 1.8 with all higher floors being clones of the first floor, leaving only 2 vertical spaces between floor and ceiling denies endermen the height they need to spawn in the first place.

I only have one harvester and collector. But it seems to work fine.

22 Sep 2011 05:25 by ElMarko

You can get a mod to stop them moving blocks. It's ace.

19 Sep 2011 08:15 by Bix

I followed this template in 1.7 and it worked like a charm. On a legit SMP server, this is ont of the best towers you can make, and your little app here above which gives the slices one by one, is wonderful for a team to coordinate on building.

Unfortunately, in 1.8 this is a nightmare : Endermen have enough space to spawn (since above the spwaning platforms there are actually 5 blocks of air) and cannot fall (since max. 2 height to "drop" to platform below). Moreover, they pickup blocks from everywhere including below their feet, and place them elsewhere randomly, breaking the whole structure.

Too bad :(

17 Sep 2011 05:22 by ElMarko

Just wanted to say this is great, I've built a one level trap so far, with a double height floor suggested by teknics to stop the mobs climbing out. I will add more later when I can be arsed, this took ages!

It does still work in 1.8.1, but Endermen will remove your blocks from the inside. You will need to repair every so often to stop the light getting in. I don't know if they can take up the floors or canal sides, but water will kill them so there is that.

May have to refine it for later versions, Kev. But many thanks!

16 Sep 2011 04:15 by derzok

Doesn't work in 1.8 - endermen will grab blocks and move them around inside. They ruin the spawn platforms so that no mobs can spawn on them. A fix for this is to make all of the platforms directly on top of each other. Endermen can only spawn if there are 3 vertical blocks for them. If all your platforms are directly on top of each other and 2 units apart, they can't spawn anywhere except for the ground floor (which is a LOT easier to repair).

If you don't want to repair the ground floor all the time, re-work your water canals so that they are located in spots where there are 2+ vertical blocks :)

13 Sep 2011 07:54 by Jay

Epic tutorial. Added a layer to the 2nd floor water channels as suggested and I'm getting GOBS OF LEWT!

Word of advise: make sure the water channels on the second floor are all 8 blocks long so the water goes right to the edge but doesn't spill through the hole or you'll have a bunch of mobs hangin in the jacuzi and not falling through.

Tried the signs instead of ladders but still getting very little string. Going to try to incorporate cacti in there somehow...

28 Aug 2011 04:58 by brybry

good stuff, floors take 4ever to build tho, 2 floors works great. kev, dude you need to make a pigfarm vid man

28 Aug 2011 06:53 by nick

awsome ill b build me one now

27 Aug 2011 12:58 by minecrafterIsaac

NVM i put 4 blocks instead of two so it was too long X(

27 Aug 2011 12:48 by minecrafterIsaac

when i got to step 3 i make the lava trap but it deosn't stick out a block and i have ladders there but dont work???? why

21 Aug 2011 01:10 by Cookie1994

Lol, my grinder became effective when i was only on the third level, squid had spawned in the water and been grinded leaving the inlsacs

6 Jul 2011 09:24 by Idkbutprobablyagudone

I wonder, if you built this dee under the ground... in a chunk that can spawn slimes... :D

6 Jul 2011 02:06 by JBJblaze

Hey, KevBlog, you should do up a YouTube video for this! ;)

5 Jul 2011 01:40 by UberPea8675

I added a second layer to the collecting floor like somebody had mentioned already, but I still have to walk the spiders into the holes. Has anybody fixed this yet?

29 Jun 2011 02:45 by SuperZOS

You know, i gotta nice idea on replacing lava with cacti. Can it solve the spider problem?

28 Jun 2011 01:03 by Marc194

May have found a fix for the spiders getting into the lava, for me they werent jumping in but Climbing the ladders. Using signs as appose to ladders seems to have fixed it, let me know if this works for you. I have noticed an improvement but who knows.

24 Jun 2011 03:40 by TwoAM

Patience my friends. With the release of pistons in the 1.7 update (if pistons are included) all the death by fire will go away and the drops will no longer be destroyed. Fun will be had by all.

23 Jun 2011 05:43 by Vietilicious

This is the best step by step tutorial I've come across.... and to truly get rid of spiders i use a cactus in the middle of 6 collection floor 1 while AFK

just stand in middle of spawner to kill spiders since the can see through blocks (use their x-ray vision against them :D

22 Jun 2011 08:08 by KevBlog

Yes, still working in 1.6. Ican press F3 I can see the name plates of mobs and my tower is full of them so the checkerboard floor works very well as a spawn and drop system. Getting plenty of items at the bottom.

20 Jun 2011 07:18 by JBJblaze

So, this method: it STILL works does it?

10 Jun 2011 08:42 by JWesC

Hi there. For those of you asking about the spiders, I believe putting blocks two spaces above the ladders will prevent the spiders jumping in the majority of the time.

8 Jun 2011 03:23 by Rob

Here is an image that I redid the center area for only 1 pickup area, later I might add a drop down from the center to a lower collection area.

goo.gl/rl5Oq

3 Jun 2011 09:11 by da_ninja

No. The one with canals down the side is rather bad.

1 Jun 2011 08:09 by FierceDeityLink0

I don't like the checkerboard at all and i really think it would work better if each floor had water cannals pushing the mobs toward the hole...im going to build one and experiment with the mob spawning area. Right now im digging a huge pit into the ground all the way to the baseplate....its going to be as tall as possible!

27 May 2011 08:10 by CHuk1994

what i found to be really useful when ii built this was wooden pressure plate at the end of the bases water troughs, so when the items get washed to the centre they activate a redstone trail all the way to my house, indicating when i have drops or when the drops stop (indicating a problem with the grinder)

16 May 2011 09:08 by FluffySquirrel

Didn't have much luck with a central trap, so what I instead did was just add more channels on the main channel floor.. I put 2 3 deep perpendicular cross pieces on each of the main water channels, and in the centre, I made another cross of water pushing them out from the centre towards the sides.. no holes to go in, but seems to help guide them towards the proper channels.

After that, I dug a central hole to channel all the flows into, and led it through a small tunnel underneath the floor of one of the main holes, seemed to help a lot, the spiders don't clog up anymore

15 May 2011 09:06 by FluffySquirrel

Hmmm, I currently have one built with around 6 levels, left it running a couple of hours while I watched a movie, to see how it would go.

Got back to find minecraft seriously lagging, and when sound was switched back on, sounded like there was around hundreds of spiders loitering and blocking the entire system up.

Soon as you go near any of the corners, they just start jumping down in swathes.. but if you stay in the middle, they must just all stick above your head, which I suspect also starts to affect other mobs spawning.

Going to try experiment with a central trap of some kind to hopefully stop the spider infestation so they don't keep blocking off the other mobs

12 May 2011 08:59 by Sbrain

Could i suggest you make a drop grinder? That way the items/hour is much higher as they can't hit the lava when the mobs die? Instead of alternating the cross pattern, keep them in line with water channels taking away the items from fallen mobs. (needs to be very tall) See Behemoth 3 for what i'm on about

9 May 2011 06:02 by Andreww

love the spawner.. however, i used teknics idea but tweaked it a lil. in the empty space in the middle, i added flowing water, 1 block deep which helps push mobs towards the main canals which take them to the lava. before this i was having mobs just standing around on this floor.

7 May 2011 04:50 by lowfuel

How do you get the 2-wide water channel to not end with one block empty? Do you just pour two water blocks really fast at the starting point? Dumb question I guess, sorry. Thanks for any help.

7 May 2011 04:29 by Minecrafter

How long should I wait before I go in and collect my booty?

5 May 2011 11:39 by teknics

hey glad my suggestion has been useful, it definitely upped the amount of mobs i was hearing fall into the water and not being able to get out (before i added to second level to the collecting floor i could hear them fall in, splash around, then get out....now once they start splashing they never get out and wind up getting killed)

I definitely get way less string, the only way to really kill spiders and guarantee string is a drowning trap which is slow. I'd say if you really need string, find a spider mob spawner in a dungeon and setup a trap there. I got lucky and found one spider spawner only 5 blocks above a 2nd spider spawner, i get tons of string now :)

5 May 2011 07:59 by Kevblog

Mdub - hehe. I guess you mean a game day but I still get loads more than that, but I do have over 10 floors. If I press F3 to see 'name plates' above mobs, my tower is full of them.

5 May 2011 07:56 by Kevblog

Niel and Dragon Tamer - I do get some string, but nowhere near as much as the other stuff. Spider don't always die when jumping but often do. Not sure of the best way to stop this at the moment.

5 May 2011 07:55 by Kevblog

Mindless, I think dirt is ok, as long as its dark. Otherwise farm animals spawn on dirt/grass.

4 May 2011 09:12 by Mdub

This mob grinder works so well. I got 10 gunpowder in 1 day! :D

3 May 2011 07:01 by DMJ

Thanks very much for this, the interactive floor plan was very helpful during construction. Also, I implemented teknics suggestion and found it works very nicely.

30 Apr 2011 02:39 by Niel

Also, can I quote Dragon tamer?

"I've built it like you said, but I had one question. When the spiders die, they end up jumping up into the lava so that the strings they drop burn as well, is there a way to avoid that?"

I'd like to resolve that problem too if possible, string is kind of important to me :P

30 Apr 2011 02:35 by Mindless

Thank you for the update. I'm still in the process of building it, btw would you think using dirt is okay for the floors? I ran out of cobble and had to use dirt for a while.

28 Apr 2011 09:24 by Kevblog

teknics - I'll have to try your suggestion when I have time. Maybe this weekend.

28 Apr 2011 09:21 by Kevblog

fredo - I leave 2 air blocks on floors. That's just enough for mobs to spawn and walk around.

27 Apr 2011 12:55 by fredo

great tutorial.
right now i'm working on a peaceful mob grinder, the goal is pork. spawn rates for peacefuls are low though, so it's frustrating. right now it's just set as a falling trap, a 23x23 spawn floor with water sucking to a fall. i wait in a pit dug below, out of the 24 block exclusion zone. the whole thing is surrounded by water and land with grass stripped away. if i add floors, how many blocks of air in between?

26 Apr 2011 10:45 by gowerski

agreed, this is sweet. really like the layer by layer plan :)

25 Apr 2011 11:22 by Dragon Tamer

I've built it like you said, but I had one question. When the spiders die, they end up jumping up into the lava so that the strings they drop burn as well, is there a way to avoid that?

24 Apr 2011 01:24 by dangleesak

thanks so much. This is maybe the best step by step tutorial I've come across.

23 Apr 2011 03:30 by teknics

I made a minor adjustment (using 1.5_01 btw)

For "6 collecting floor 1" I made that layer as you suggested, however I was having MOBs jumping out of the collecting streams and basically just hanging out in the tower.

So i made a 2nd layer of "6 collecting floor 1" except without the water, this way when mobs fall in the collecting stream they have no way out.

I'm still having some problems with spiders, the majority of them can still avoid the collecting holes, once i get near the hole 3 or 4 of them will suddenly jump down, then i simply walk them to the lava.

Other than that this has finally made me capable of stocking up on gunpowder to finally make some TNT, woot. Got a basic 5 level version running, done all with stone i mined myself woot.

thanks for the posting, your interactive schematic thing helped tons!

2 Mar 2011 02:28 by ER1C0

Nice! I'd also mention lighting up some of the caves/areas around you in order to increase the mob spawns in your trap