I know this, but if you watch my video, you'll see it doesn't make sense, I attack a 5000 durability iron door with my bare hands, each hit only deducts 1 durability, but I can get about 10 iron from each hit, I think there must be something wrong.
I'm playing a modded game, and I originally thought it was a mod issue, so I removed the mods and opened a vanilla Navezgane world, and just like in my video, I was able to harvest iron with my hands.