https://vid.me/Fq7Z

take any mob who hasnt a loot table

Shhh, nobody is supposed to know about that :)

Basically that hole in the ground is to get around some mods dropping items in the world directly when a mob is killed, rather than letting Forge spawn them. While the factory is learning it kills a fake mob at bedrock and any bad-mods drop their loot down there, which I hoover up to learn. (That is why the manual says don't build the factory below Y=10)

If all mods played nice and just let Forge handle it, then everything would be fine, but that is of course up to the mod author.

One option may be to encase the learning area in bedrock to stop anyone from easily adding items.

Or you say that no item coud get inside oder outside of that area

I just use a standard function from Forge that gets me all the entities within a certain area. I don't think there is a simple way of identifying entities dropped by a player rather than genuine loot drops - though I could be wrong.

I mean that there is an invsible boarder at the end of the 3x3x1 room that no item could get in the room or out of the room

Is there a command to stop the learning progress manually?

No, without the learning the mod wood never generate anything.

How many mobs will spawn for learning?

By default 500 mobs, one every 20 ticks.
That can be changed in the configuration file.
The more mobs spawned the more accurate the loot percentages.

Another option would be that the learning works in an extra dimension so that nobody could get there who isn't allowed.

That was a consideration earlier on ...... I was a bit reluctant to create a dimension as I think it would be a bit of an overhead.

sorry to chime in couldn't you talk with tema about using the Extrautils2 quarry dimension for it?

Of cause didn't think of that just thought most mod packs with woot will have eu2

but then that mod would have to be installed to use the dimension, otherwise its back to creating your own or using an alternate method.

This is now being addressed. So I'm going with a box in the sky to handle this, which will be surrounded by barriers. The box will only exist when required and will then be removed. Hopefully this should stop this exploit. (Still not the best solution but I'm hoping it is better than before!)