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Big mining drill - drain

How does it really work ?

Wiki says: "unique property of reducing resource drain from mining by 50%, which means the resource underneath the drill's mining area only has its richness depleted half of the time. This effect directly multiplies with the productivity of the drill in terms of the amount of resources that can be extracted from a single patch. "

- which sounds like drain makes a bonus amount of extractable resource. So more "drain" means more resource, it sounds sounds better ?
well, also wiki says, the higher Quality factor makes drain lower.
Base miner Drain 50%
Legendary miner Drain 8%
Does it means, better quality miner gives lower the bonus ?

https://wiki.factorio.com/Big_mining_drill

I believe "Drain 8%" means there's only an 8% chance that the resource is depleted during one mining cycle.

Yep, that means if the mining drill runs 100 mining cycles, with 40% productivity and 8% drain, you get 100 + 40% * 100 = 140 items, and just 8% * 100 = 8 resources are actually consumed from the resource field, so if you had 1000 before, you now still have 992.

Because of this and mining productivity in addition, mines are practically infinite in the late game.

Tertius wrote: Thu Feb 06, 2025 7:38 pm Yep, that means if the mining drill runs 100 mining cycles, with 40% productivity and 8% drain, you get 100 + 40% * 100 = 140 items, and just 8% * 100 = 8 resources are actually consumed from the resource field, so if you had 1000 before, you now still have 992.

Because of this and mining productivity in addition, mines are practically infinite in the late game.

I am not sure if I understand your math equations, so I made a test.
Burner, Electric miners do 100 coal from 100 patch.
Big Miner does 198 coal from 100 patch.

No modules or research involved.
I made test 3 times, result same.
Dont know what math equasion turns 100 coal resource patch by processing 50% drain into 198 pieces in the box. Anyway I am glad that "drain" actually means positive thing. 1000 coal patch produces 1998 pcs. Looks like, it eats 2 resources for own purpose.