Talk:Tutorials/Mob farm

Snow golem help
Maybe you can use snow golems to make this work, can someone please help me with this?
 * Or pistons?Phsycic 21:37, 14 April 2012 (UTC)

Spiders, they suck...


I built this Mob Farm accordingly to the tutorial, and it's pretty efficient ! There is still one problem though: Spiders! Since they can now climb wall, it's possible that they block the funnel ! Emptying 1 more ceiling block seems to correct this. --Yamitatsu 16:37, 17 January 2011 (UTC)


 * Thanks a lot for the feedback! I didn't really notice the lack of string production, and I certainly didn't connect spiders' new climbing ability to any issues with the farm. I added your image and solution to the main page. MrMatthew 19:16, 17 January 2011 (UTC)


 * You're welcome^^
 * Well, in fact, it didn't just stopped the string production, as you can see on the screenshot, many mobs were stuck behind the spider, so the whole process was stopped :/
 * I let it activated the whole afternoon with the small correction, and so far, no more interruption :) Filled a large chest with all the loots:) I'm thinking about making another 50x50 spawn room above the first one, this could maybe give a lil boost to the production^^


 * Anyway, thanks for the tutorial, well explained :) Though I had to make some schemes on OOo Calc to be sure not to do any mistake since English isn't my mother-tongue, lol^^
 * --Yamitatsu 00:39, 18 January 2011 (UTC)
 * I've heard that a block of cacti in the right place can stop spiders clogging the trap, and with the new dispensers needing bows to make, yes, we do need that much string. --Nahere 01:00, 18 January 2011 (UTC)
 * Even by updating the funnel to properly funnel and kill spiders, the fact is that many won't even end up in the kill area, since they can just climb their way out of the canals to begin with. If you're looking to kill spiders, this is probably not the best way to go about it, so a spider-specific farm might be in order. Hmm, new challenge for me! MrMatthew 18:49, 18 January 2011 (UTC)
 * Yeah, not that much spiders, the fact is they can jump easily above the 2 blocks canals, maybe with 4 blocks it would prevent them from stay safe outta water^^. Though, sometimes when i go check through the glass along the funnel, i see 4 or 5 spiders in it, i guess that's because i come closer and they try to get me^^.
 * --Yamitatsu 15:19, 20 January 2011 (UTC)
 * I was told that spiders cannot climb sandstone, so I'm planning to shut my farm down and put a line of sandstone around the inside of the canals. I'll let everyone know how that goes when I complete it. (EDIT: After checking the sandstone page, it does appear that spiders CAN climb sandstone. Hmm, back to the drawing board I guess...) MrMatthew 18:57, 20 January 2011 (UTC)
 * Well, it's kinda rare, but spider can still block the funnel, they seem to climb the wall on the side, i'll try to make it 4 blocks large and add a row of cacti on each side...
 * --Yamitatsu 09:52, 24 January 2011 (UTC)
 * I'm pretty sure they can't climb soul sand (the small amount of invisible gap makes them fall, I think) --Thevdude 15:52, 26 January 2011 (UTC)
 * You can make the hole MUCH deeper so that the funnel is 5 blocks high. Then, a) make alternating (not checkerboard) cactus fence along the top 3 blocks of the 5 block high wall or b) make it normal height AFTER the first drop and make a tunnel high up the wall above the drop, and spiders will walk/climb in! Put signs at the front end of the tunnel and put water sources after them, making a SECOND funnel (without drop) to kill spiders! --stripminer123 21 April 2011

Thanks for the tutorial! I built a farm based on this design. It did have a spider problem in the funnel which I have managed to fix. It seems like spiders are way less likely to be able to climb if you take out every other block. So from the base of the center hole to the first downward drop (where the red circle is on Yamitatsu's picture), I take out ever other block on top. That keeps them flowing faster. They still kept getting stuck at the red circle (I think because the drop point has two adjacent blocks) so I added a second fix: I added a third lava stream that comes into the tube from the side at the red circle. This means that if spiders are clinging to the dropoff, the lava gets them (this lava also gets some of the other mobs coming through). I still seem to be having trouble with spiders never making it down the funnel though. I think a fix for that might be to checkerboard the inside of the canal chutes above the water so that they have a harder time climbing out of the canals once they get in. I have noticed that they seem to occasionally stick at the very top of the chute (right where the four main water flows meet), so it might also be a good idea to make the hole drop a couple more squares, and then take out every other blocks within the chute so that they can't stick in it. (Mirth23 04:26, 28 January 2011 (UTC))
 * Interresting fixes:) I'm thinking about going to the Nether and collect some soul sand, since spiders can't climb it, and replace every sides block of the canals with it, to see^^ If it works i'll post some detailed schemes here^^
 * --Yamitatsu 07:53, 28 January 2011 (UTC)

I made this same mob farm on a server where I do not have difficulty control. The mobs aren't quite as abundant, but it still works great IMO. The issue is, I think, that spiders end up overspawning, and never getting into the trap. I was able to get around 54 sulphur in about an hour when moving around and such, but when I left myself at the collection point overnight, I ended up with hardly a stack more. I made a glass roof where I could go check on a section of my trap and there are tons of spiders. Even if I lure them over to the canals, they don't go in. I may try something with cacti or checkered walls. I also noticed that when the spiders got to the drop down just before the killing mechanism, that third block wasn't enough. I had to make it four before they stopped hanging onto it.

--Sevalecan 05:15, 29 January 2011 (UTC)
 * It will work and then, somehow, spiders will still block the canal at the 4th block, they do climb the side walls, so no matter how many additionnal block you dig, they will be annoying, i'm still collecting enough Soul Sand to make the canals' sides, since it prevent spiders from climbing.
 * --Yamitatsu 12:27, 29 January 2011 (UTC)

It's possible to put a cactus in the funnel to kill off the spiders. If built as described in the tutorial on the first drop, put a sand with 2 cacti on top. You'll have to punch a hole in the wall. This will mess up the water flow. To fix the water flow, at the beginning of the funnel, where the mobs drop in, you want only 1 water source on the same side as the cactus. This should give a diagonal flow to the water allowing all mobs to bypass the cactus and to prevent items from being stuck in front. The water flow doesn't quite reach the end of the funnel, so you have to place 2 more water sources. One goes next to the sand block after the drop and the other needs to be put into the wall in front of the sand. This will allow the water to flow properly into the lava. This has removed all spider issues as they immediately kill on the cactus.

On another note, you can tweak the funnel without switching to peaceful by blocking the hole in the ceiling and then making changes

--Venix1 19:59, 29 January 2011 (UTC)
 * I think Cacti is the solution yes, coz after spending hours putting soul sand everywhere (lol) i figured out that they CAN climb soul sand !!(that's not a 100% though) dirty spiders !!!
 * I'll try that cacti thing :)
 * --Yamitatsu 23:15, 29 January 2011 (UTC)
 * They might not be climbing the soul sand - I believe that they can stick to the ceiling if they've got a 2x2 area above them. My checkerboard + extra lava seems to have cleaned up everything.  I've also got a friendly mob farm higher up going into the same chute, and I think that falling cows tend to dislodge the spiders. ;) --Mirth23 05:47, 31 January 2011 (UTC)

On that note, I added a new section called "Multi-level Canal". Yay. :) --BURRITO333 01:47, 1 February 2011 (UTC)

Built the farm as suggested and had issues with spiders jamming up the funnel so I dug 4 blocks outward at the third block on the top of each drop point and placed lava in the far end. The lave flows to the very edge of the tunnel without entering and normal mobs pass by it unhindered. Spiders however just love to investigate that strange glowing thing and brush up against the lava enough that they burn themselves to death. Problem solved!


 * It could also be solved by just putting the lava killer up closer to the mouth of the funnel, and just have the rest of the funnel move the items. I just wanted to keep the killer in the corner of the flow, thus it ended up farther down the funnel. Still could help to plant some cacti. MrMatthew 20:11, 2 February 2011 (UTC)


 * One problem with the cactus... It eats your items!!! --Eldonman101


 * True, but if you don't kill the spiders, they block the funnel and you get zero items. Some is better than none anyway. MrMatthew 17:48, 3 February 2011 (UTC)


 * With Cacti instead of doing something like putting them in the main path I have found that placing a cacti in the wall just under and before the lip (where the ceiling comes down by one block) solves spiders blocking the funnel as they dont just stay up but bob up and down a bit so when they bob down they hit the cacti injuring themselves and maybe falling so eventually either the cactus dies from cacti wounds or falls into the water and is carried to the lava. To insert into the wall just make a plus sign in the wall with the centre of the plus being 2 blocks deep and the edges one block deep then place sand in bottom of plus and cacti on top since nothing can get into a one block hole (slimes are exception but not likely to happen). Getting the spiders to the lava doesnt guarentee string though as they are only one block high and will try to climb the lava and will be on top of it and string will most likely burn.  I am getting at least one string every 15mins though and no more blockages lasting for long.

Fierkraag 20:04, 7 February 2011 (GMT)


 * Minor adjustment to previous comment put cacti at the same height as the lip instead of one block below and put 2 on each side of the wall for each lip and it is a lot more efficent blockages simply dont happen at all and spiders get stuck in cacti while passing as they climb up into the cacti and die thus dropping string in water, this has actually allowed me to get quite a good chunk of string quite quickly if not nearly at the same rate as the other items. Bit emmbarressed that it didnt occur to me earlier to raise the cacti up the top of the wall.

Fierkraag 20:47, 7 February 2011 (GMT)


 * I found a way to get around this AFTER the Halloween update. Kiershar has nice demos on this. Simply make the funnel 4 blocks long AFTER the hole, put the lava TWO blocks above the water, make ONE water source on ONE side, put a cactus in the corner on the same side as the water source to kill spiders(against side wall so water is flowing away from it, saving the drops), make a 1x1 hole in the FRONT wall (the one with lava hanging over) opposite the side with the cactus(make a drop, so there is 1 block air above the 1 block wide stream), and 7 blocks along the mini stream (which will bring the items) make a 3 block drop with cacti on the 3 surrounding sides(1 block above the water, not same level to kill chickens/slimes. Watch Kiershar's vid "Updated Lava Trap" for help.

stripminer123 16:25, 20 April 2011 (GMT + 08:00)

You can also use trapdoors instead of soulsand. I use it and it works pretty well, it's hooked up to redstone so that I can open and close it by pulling a lever. Note: sometimes a small group of spiders can still lead to a 'funnel-block' (that's how I call it). VDTim 14:26, 28 June 2011 (GMT)

I'm loving this trap. I also tweaked the funnel so that I can kill the monsters with a "drive-thru window" rather than the lava, and pick up the XP orbs. The principle is to funnel them into a tight 1x2 chamber where only their heads show, and then come up on your end with your legs at their head level and finish them off with stone swords.

Being one block higher than them lets you avoid eye contact which sends them into attack mode. It's also worth tweaking your end so that you can quickly side-step any hissing creepers and get out of eye contact.

Once the mobs have dropped enough, you can plug up the top block with dirt, take out the bottom block, and let the water safely funnel the drops right to you, just like a drive-thru window.

The only caveat is to make sure the funnel is properly flooded. Creepers exploding in water do no property damage, but if they find any dry spot to explode on, they wreak havoc.

Using this tactic I can get to L15-40 in one to a few hours of killing.

--Ronnybiggs 02:29, 31 March 2012 (UTC)

Notification System
At the end, it might help to make some wooden pressure planks that lead up to the surface with redstone and light up a torch or make a sound with the note blocks so that you know you've got items awaiting you... Eldonman101
 * On mine, I do have a redstone wire and torch system that spirals around my mining shaft (I was actually thinking about doing a tutorial on it) that let's me know when there are items. However, the rate that this machine kicks out items, it's almost always going to be on. Once you assure the machine is working, the need for a redstone alert system is a little unnecessary, but I urge you to make this farm your own! MrMatthew 18:56, 20 January 2011 (UTC)
 * Yeah, I'd probably be a waste of time. Anyway, my work has begun! I've just been reading about it. It would be nice to have a door you can open/close at the end of the collection system with a lever so your items get in but no water can... It would make it so much simpler to make the collection system (the stream wouldn't have to be so long). -Eldonman101
 * The length of the stream prevent you from being too close of the spawning room, wich would result in zero mob in that area (24 blocks around you), at least i think so^^
 * --Yamitatsu 18:26, 30 January 2011 (UTC)
 * I set up a system where I have a wooden pressure plate and a clock generator running to an AND gate, then that goes to a note block, making the note continue to beep, letting you know there are items.MattSoave 10:11, 30 January 2011 (UTC)
 * Good idea, but it's probably really annoying. You should have a lever on the clock generator to stop it from beeping when you have enough items or you're just sick of it. --Eldonman101

Ladders vs Signs
Is there any benefit to using ladders vs signs for retaining the lava? I created a mob farm according to these plans and used signs... It seems to work fine. My reasoning was that the mobs might climb up the ladders a bit and then they would have a higher chance of their loot dropping into the lava when they died. Thoughts? --Samuraifalcon 20:45, 24 January 2011 (UTC)
 * I didn't think mobs could climb ladders. That would be the only difference, I just use ladders because I always have ladders on me when I'm mining. MrMatthew 17:10, 25 January 2011 (UTC)
 * I believe mobs have at least the mechanics to climb ladders, as recorded in the article on Ladders and the corresponding talk page.  Mobs may not have the A.I. to "climb" one or more ladders as a part of their pathfinding, but the mechanic of climbing exists for them if the mob moves next to the ladder, which would be likely here. Also, you make a valid point about already having ladders. Anyways, a minor difference but some may be interested :) --Samuraifalcon 19:45, 25 January 2011 (UTC)
 * Well there is always the fact that ladders take less materials. And you know how practical wood is. But, one upside is to the signs is that you can make it say, "DIE, CREEPERS!!!", or "DO NOT REMOVE", or... Well you get the point... --Eldonman101
 * I can think of two reasons to use signs rather than ladders. 1) Mobs can climb ladders. 2) Ladders have a collision mask that can stop mobs but signs aren't physical objects. --Urian 18:35, 3 February 2011 (UTC)
 * YOU NEED LADDERS in the new funnel (shown above in spider section) because mobs need to climb it to the lava. --stripminer123

Gallery
Put screenshots of your mob farm in action in the gallery (preferably with description). Try to put some interesting add-ons that others might want to see and copy. For example, a picture of lava running around the entire farm that you can turn on/off so you can stop the farm and turn it back on. --Eldonman101
 * Would be great, but lava stay soooooo long after you remove the source :/
 * --Yamitatsu 10:18, 30 January 2011 (UTC)
 * Plus you'd have to somehow make the lava go that far... --Eldonman101
 * I have a 50x50 ANIMAL farm on the surface (with 2 13x24 extensions) and it works GREAT at night. I put torches inside, remove torches around it, put it on peaceful and it spawns mobs like CRAZY. I got, like, 30 porkchop in 1 night. Problem is, you can't get wool from burning sheep. --stripminer123
 * If you dig a mob farm with the floor being layer 13, the open area and walls layer 14 & 15, and ceiling layer 16, you get lots of diamonds! --stripminer123
 * I can't post pics "no permission" apparently.
 * I can't post pics "no permission" apparently. --Blaze0

You can use a combination of Pistons/Torches or the BetterThanWolves mod's Redstone Light block for toggleable farms. I used pistons at the end of my killer for a fun buildup.

Seems like pistons strategically placed to plug up the funnel is the best choice. No point in needlessly killing your farm animals. :P --Ronnybiggs 03:12, 31 March 2012 (UTC)

"but what do you really need that much string for anyway?"
Given that string is needed for bows, which are needed for dispensers, and I'm presently trying to make quite a lot of dispensers, this seems like quite a silly question to me. Also I like to go fishing now and then, and man do fishing poles wear out quickly.

you can stack the used fishing pole on the unused one to get infinite uses out of two poles.~--Wetterfree 01:59, 7 April 2011 (UTC)

Wool. --stripminer123

if you're using string to make wool, your doing it wrong. --Lazeman 04:17, 3 October 2011 (UTC)
 * If you're spelling "you're" like that in this context, you're doing it wrong. 78.105.8.153 10:48, 6 April 2012 (UTC)

It will also kill slimes
Yes, it will. Got a big slime trapped in my 50 by 50 mobfarm yesterday and I got my slimeballs. I think it's working better since the 1.3 update.

Not guaranteed, because slimes only spawn in certain chunks, though. Pitzik4 17:07, 7 July 2011 (UTC)
 * I found some lovely slimeballs waiting for me when I checked on my farm as well. A 50x50 floor covers several chunks, so there's a good chance you'll get some slimes now and then. 78.105.8.153 10:49, 6 April 2012 (UTC)

Going up?
What do you guys think of a farm built high up in the sky? I was thinking of building a wooden "box" about 30 blocks in the air and placing stone blocks on the ground. This way the mobs could spawn, drop down and kill themselves. And you can get 4 wooden planks from a single block of raw wood, making farming construction materials a little easier. What do you think?
 * Like a mobtower? (They're patched) --Jasonlasse
 * Yeah... So you can't use it, eh? That's dull. -DLockX
 * Well, you can. But it doesn't work that good anymore. It's because of the (0,0) chunk. Before it was patched, the spawn-rate was increased in the 0,0 chunk. And this is where you place the mobtower. --Jasonlasse
 * Kiershar's 75x75 sky mob trap gives 50 items a minute (LITERALLY). --stripminer123

Unclear Explanation
Maybe I'm just being dense, but I don't quite follow the "Digging the Shaft" section. So, I dig one room at bedrock, one room just above the first room, and one room with the floor at 16/17 blocks above the bedrock. What's the point of the second room, couldn't I just put all that stuff in the first room? The third room, the one at the 16th block from bedrock, that's the one to be expanded into the 50x50 collection area? The 4-block hallway, is that dug from the middle room, or from the top room, and does it matter which direction it's dug in?


 * The second room (The one right above the bedrock room) is entirely unnecessary. You create the 50x50x2 room at the 16/17th level. The four block hallway is also dug at the 16/17th level. It can be dug in any direction. I recommend reading over all of the instructions first. It will clear things up. Sartanpham 03:31, 14 April 2011 (UTC)

Can it be smaller?
does it have to be 50x50x2? that seems like a heck lot of digging and 5000 blocks is a bit too much. can the farm be shrunk to half-size 25x25x2 or does it have to be 50x50x2? i tried the original and quickly found out why it had to be by the bedrock. there was a huge cave system right in the middle of my farm and i didn't have the heart to go and fill the entire cave with stone.

I made a 13x24 animal farm on the surface. (extension to my 50x50 animal farm, *hanging* over ground) It's OK. --stripminer123

The size does not matter as long as it takes mobs 30> seconds for the mobs to get to the death room. At about 30 seconds after being spawned if a mob was not within 24 blocks from you they start despawning. The size issue 50x50x2 size is large enough to spawn lots of mobs but not to large for the mobs to despawn before they die. Personally I perfer an 80x16 sized Dark Room. ~Dcat

Maximizing spawns
To get maximum spawns, find all caves 3 chunks around the farm and light them up. Them all of the limit of 200 aggressive mobs will be IN the mob farm. If you find dungeons in the farm KEEP THEM. The spawner is handy. Keep it within 16 block of a wall - that's the limit you have to be within to make it spawn.

--stripminer123

Cactus in mob grinding apparatus
I'm just talking hypothetically here, but would it be possible to replace the lava with a cactus standing on top of a sand block with a ladder on it ? If that worked, i believe someone spawning near a cactus could start a small mob farm way sooner, skipping the need for finding lava. It sound good in theory. Kinperor 01:12, 19 May 2011 (UTC)

Cactus Mob Farms have been used since the beginning of Minecraft. The only problem with it that Lava does not have is if the mob dies on the cactus and the drop hits it the item will disintegrate. Lava on the other hand if positioned correctly 100% of the time the items will flow down to you. The Drowning trap gets you the item 100% of the time if you DONT have dead zones in your path, but the Drowning traps take longer to kill then by Lava or Cactus. ~Dcat

Mobs going trough walls?
A few days ago a spider blocked the funnel (again :<). When I reconnected a creeper came trough the wall and destroyed a part of the lava trap, releasing the other hostile mobs. how is this possible and how can I prevent this? VDTim 11:19, 29 june 2011 (GMT)

Wierd Glitch
I Built my mob farm according to the specifications here, and edited the funnel slightly to make it spiderproof (message me if you want a schematic), however, I'm getting an odd glitch I cant understand. Although they're dead, mobs are still getting through. They simply stand, unmoving, in the way. They dont attack, they dont make sounds, they just stand there. I take no damage when I come into contact, and the only reason I'm looking for a fix is cause they clog up my collector. I was wondering if aanyone would be able to explain why this is happening so I could work on a fix?

--Lawson 19:02, 3 July 2011 (UTC)

Spiders and the Canals
I've semi completed my farm. It racks out a lot of goods. It is 25x25, but is 10 floors tall, all stacked on top of each other. I put in viewing rooms with glass on one side to see mob spawns and make sure there is no light, etc on each floor. I also grassed all the floors but the bottom two so I get all the animal spawns too. The only problem I am having is, when I go view, the spiders are just chilling. They don't even fall in the canals at all. Not a funnel problem, because they never make it there. I watch them actually just crawl right across the canals.

My question is should I tear all the grass out along each canal and replace it with soul sand to make them fall into the canals instead of crawling across them? I know the string is not that big of a deal to have, but they are still spawned up there, taking the place of what could be something else.

Other than that it is great idea and been working quite well.

Someone found a way to separate sheep and cows!
(untested, but 73 people thumbs up'd it so I think it's true) if you have an extended piston, and a block 2 blocks above it, sheep can pass through it but cows can't. Cool12309(T 03:04, 22 August 2011 (UTC)

Dear person who wrote this guide
I'm having a small problem with the canal-style mob farm. I get more mobs in the lava shaft that I ever imagined possible, but the lava that's killing them is also incinerating the items they drop. So, I thought to myself, maybe I made the separation between the lava and the water leading them there too close. So I put a block of space between the two. It turns out that was enough room for the mobs to slip through unharmed, turning my mob farm into a pants-crappingly terrifying vision of human folly. How do I fix this? (The item incineration, not the folly thing.)

Sincerely,

Stabbed, bitten, arrow'd, exploded, and burned

Darthwiggles 15:31, 23 August 2011 (UTC) I hope this helps solving your problem. --Yatsufusa 20:43, 23 August 2011 (UTC)
 * Dear stabbed, bitten, arrow'd, exploded and burned Darthwiggles. I didn't write this tutorial but I think I know what happened: When the lava blade burns your items, then something with the measurements of your trap is off. Maybe you did the step down on the water stream that's carrying the mobs too late. Here's a short video that explains a kind of mob grinder. It has a good transparency on how the lava blade is done. Just ignore everything else and focus on the part in the design where the last part of the lava stream comes in contact with the mobs.

What Did I Do Wrong?
I followed the tutorial exactly, but I am barely getting any mobs to come down the shaft. My cave is completely dark, all the water flows properly and I am getting spiders, zombies and skeletons to spawn, but only 3 or 4 at a time TOTAL. What could have possibly gone wrong? --TylerBrach 04:37, 30 August 2011 (UTC)

Hey, it sounds like if you have this problem then you need to dig some strip mines through the chunk and find ALL the caves. if there are mobs in the caves then there won't be mobs in your farm. To stop them spawning in the caves fill the caves with torches and your problem should be fixed. -- Dunkey4

Same here
I've got a similar problem. Mobs are clearly spawning and getting carried to the center hole, but they aren't dropping down. I can here dozens of skellies and creepers up above my head if I tunnel back up the funnel.

Although my room isn't exactly to specifications, I've tested and re-tested to make sure I've got good waterflow. There are no dead zones, and I've tested by falling into the canals and making sure I get carried to the center, and then I fall down. There's a small issue: if I fall down the back wall of the funnel, the water isn't moving forward, but I don't think this is the problem: very few mobs are falling down at all, and I'm pretty sure that it's random jitter/jumping that is letting anything through.

Any suggestions?

NathanielTagg 16:03, 17 February 2012 (UTC)

Nathanie first off fix that water problem. It might not be having the effect of the mobs not moving through but it will stop some needed mobs. What your cases sound like is your spiders are trapping your mobs so go back and check to see if you built it correctly. I suggest separating the mobs in general by making a 1x10 opening with water heading water flowing diagonally twords. 1x10 makes sure that the spiders get in the pathway and no 2x1 high mob gets into the tunnel. Once you go a few blocks in you can narrow the hallway slowly to 1x2 and take the spider to a seperate killing area. I am not for sure that this is your problem but IF the spiders are clogging your trap then try out the idea I posted above. I know what I posted above works if set up correctly. What I described you can view in one of the earliest Ethose Lab's LP Series episodes. ~Dcat

Compact Mob Farm
I've followed the instructions carefully and I believe that I set it up correctly. The mobs do not spawn as fast as they should. I would be getting around 200 items/hr.

Is this method outdated or patched? Or did the spawn rate change in 1.8?

Re: Mine is experiencing about the same rate as yours on the Xbox 360 version which is at Beta 1.6.6 as of right now. The instruction page says it experiences variations on regular worlds, and that making the ceiling two blocks higher will make it more effective. Do you have it on a flat grass world? I have it on a regular world, and I built it with the 4-block high wall variation. I'm going to try adding the two extra blocks of height to the walls see if it helps. It might be worth it just to build a second floor too.

I don't know who the original poster above was, but I had a similar issue. Eventually I realized it was likely a matter of difficulty: I'm running in normal mode, in hard mode spawns would be much faster. I have quite a few other issues with the CMF, though, mostly because I wanted to feed the mobs into an XP+item farm: --Mental Mouse 11:39, 13 June 2012 (UTC)
 * Spiders: Some of them were simply falling and dying, but a significant number were climbing down intact.  I eventually suspended a block in the middle at the top of the dropshaft (same level as the ladders to slow monsters from upper levels), and that seems to have stopped the spiders.  (Yeah, I'd need a different solution for a 2&times;2 shaft.)
 * In the original plan, why are the canals, and especially the shaft, 3 blocks wide instead of 2? This makes construction of the killing floor and item retrieval wierdly difficult, and lets some monsters target me from odd angles.
 * My first attempt at a fix had trapdoors in the floor so i could dash in to grab the items. Unfortunately they also blocked both items and XP orbs from moving to me unless I did dash in.  Also, mobs falling on me....
 * My second attempt had a switchable flood to wash items and XP to one side. But I had to both eliminate the trapdoors and move my perches to a level above the monsters.  Cue skeletons shooting at me on the way down (or when I was standing at an angle, corner-wise to she shaft), and creepers would still occasionally go off.  Also, XP orbs tended to get stuck on the floor or behind the glass barriers.
 * Eventually I got serious, and added a second stage: A 2-block-wide covered canal starting next to the drop floor, and feeding monsters to a 1&times;2 slot where I could safely kill them from below (1&times;2 opening with glass above it), plus pistons under the end of the canal to push items into reach.  I also modified the original flooder to wash items from the drop floor to the canal.  This version seems to be working pretty well.  If I decide to let the spiders back in (for spider eyes), I'll probably floor my access window with slabs so they're at least stuck behind it.

About spiders and mob spawning
There are some interesting things in the following pages:

Moreover, because spiders can draw line of sight through a solid wall, they will enter pursuit mode even when the player is completely cut off from them, so long as they are within the standard aggressive mob's 16 block search radius => Spiders don't fall in the central hole but stay just before you in the spawning room.
 * Spider page:

There must be no players and no player spawn points within a 24 block distance (spherical) of the spawning block
 * Spawn page:

According to this it seems better to avoid staying to close from the spawning room. You should dig a deeper central hole or a longer funnel if you would like to stay AFK during farming.

A last thing about spiders blocked in the funnel: a piston connected to a clock circuit and placed in the ceil forces the spiders to go down and solves the problem.

Tunnel and mob room connection
I do not understand how to connect the tunnel and the mob/cannal room to each other. I built my room on bedrock and went up 17 blocks and built a 4 block long tunnel in one direction, please tell me more specificly what to do next. I would love it if you could post a video on your walkthrough. I would also like to say i got 6 diamonds in the shaft on my way down, good spot right?! Thank you!!!

Mob Spawning Behavior
This may already be covered in another page, but this bug will apply if you don't have a 312x312x128 area lit up around the chunk that the collection point is. Since it will cause mob farms to gradually stop working, it might be a good idea to cover this in this page. Inquisitribble 19:25, 12 November 2011 (UTC) --> Adding a 40x40 rail loop that passes through the collection zone provides a quick fix to this bug.

Canal Farm as an item AND XP Farm
This is probably obvious to most of you, but it should be noted you can easily turn the canal style farm into an XP farm as well. If you set up two pistons at head level for the enemies (one on each side) down before the lava blade, and wire a switch to both, you can effectively bunch up enemies in on area quickly. Leave a whole in your wall, and fire in with arrows. The XP orbs and items will be flushed to your collection area, and you can go pick them up. And when you no longer feel like getting an XP farm, or need more arrows, switch it back to a pure item farm for awhile.

Warning, creepers may occasionally explode on the pistons after one hit, but they can't destroy it. (I've tested this on a few creative mock ups I made, and one in my survival mode) and they wont grief anything. However you will not get the XP orbs for the things it kills.

One other nice thing, by doing this, you can rather easily get music discs. The skeletons can see you (and occasionally hit you! So be warned) but they often hit their comrades. Including creepers. In about 20 minutes, I got 2 music discs.

If people are really interested, I can show a mock up of the design. User:Rylkan 11:05, 20 January 2012 (UTC)

Won't Work in 1.2
The top of the page says it won't work in 1.2 for canal-style farms. But why? The release notes for 1.2 and the mob page don't give any reason either.


 * Mobs will avoid falling from 2+ high areas now, so getting mobs into the canals can become very difficult.

A fix would be to have the canals on multiple levels... --94.193.254.136 18:42, 6 March 2012 (UTC)

Update - I tested this in creative mode. It seems mobs will still fall >2 blocks if there's some water to break their fall.--94.193.254.136 19:19, 6 March 2012 (UTC)

I created a mob farm about Y - 200 based on Etho's mob system design. Worked great when I first switched from peaceful to hard. I exited the game and came back later and mobs no longer spawned in the farm...

I do not understand the problem you are having. In 1.2.2 I made Coestar's Mob Canal and in minecraft 1.2.4 I noticed Ethos also used it in Pre-Beta and since its the same set-up that Coestar used. The Canals work and I think you are understanding the release notes wrong. Mobs dont walk off the sides if the drop is 2< not 2 or Greater just Greater then 2. ~Dcat

Pressure plates and doors
So I've built a mob farm based on the canal one on this page, and I was planning to add a system of concentric squares of iron doors and pressure plates as suggested in the guide. It's going to be a lot of work so before I do that can anyone confirm it's actually worth it? I'm not convinced that mobs are actually going to spawn in a 2-high area with a pressure plate on the bottom after doing a couple of tests in creative mode: when I put down zombie eggs on pressure plates in a 2-high room, the zombies initially treated the pressure plate as filling its entire block and the zombies spawned with their heads in the ceiling and then fell onto the plate. Will that prevent them spawning in survival? Will I need to raise the ceiling by another block if I do this? 78.105.8.153 10:58, 6 April 2012 (UTC)

Why at bedrock?
This guide focuses very firmly on digging out the chamber near bedrock. What is the reason for this? I can't find anything in mob spawning rules that favor rooms close to bedrock, apart from getting mobs that spawn below level X. --Melwil 13:46, 26 April 2012 (UTC)
 * My guess is because of all those diamonds you mine while digging out the farm --50.47.130.157 11:07, 28 April 2012 (UTC)
 * The spawning room itself is built above level 15, so no diamonds in those 5000 blocks. There is more to be dug out, sure, but I don't really see that as an argument for why it should be built at that depth? -- Melwil 13:56, 28 April 2012 (UTC)

Compact Mob Trap not working
I used the "Compact Mob Trap" instructions and followed them very carefully and made sure I had the right dimensions. I waited ten minutes and nothing fell at all. I tried putting two-block high openings in the walls of some of the rooms, assuming the mobs had no way to get out to the canals with the rooms blocked in, and nothing happened. The only thing that happened was it allowed hostile mobs to spawn under it during the day because of the shadow it casts, but no items are dropping. Does it have to be exactly 24 blocks off the ground? I made it 30-something. Has anyone else actually built this trap? 174.100.170.166 19:36, 8 June 2012 (UTC)

Edit: Sorry, I took "floors" somehow to mean rooms like enclosed levels in a building I built the actual floors correctly and it's working.

Cavern Lit, but only little mob?
Hi, I just built this mob farm according to tutorial. But well, it seems only a bit mob that spawns. When I wait for almost 5 minutes at the collection point, no mob come. Then when I check the mob farm area, what I found is only 3 Skeletons and 2 spiders, nothing more. And about the cavern that surrounds the farm, I lit 'em all, but it's still hardly spawn any mobs. Did I do something wrong? Plus I just heard that it's better to built this farm under the ocean (According to Video reference in the article). Do this affect the spawn rate?