Allows you to grind aluminum into Aluminum Powder (used in star formulae) and silver into Silver Powder (for mirrors & paint). When you wind the grinder, it incurs a 120 second (base) endurance timer. If the grinder runs for more than 20 seconds without being wound up, it will break (ie. it will always break when you stop). The cost to repair it is 4 oil and 4 leather.
Built: in a compound, uses 11x19 cells
Skill/Tech required: Basic Chemistry
1) Load the hopper with metal.
2) Click "Start grinding [metal] into powder."
3) The grinder will run for 20 (teppy?)seconds, then stop. If someone selects the grind option while it is already running, the timer will reset and it will continue running for another 20 seconds.
4) For every 15 seconds the grinder is running, it will convert 1 metal to 10 powder.
5) When the grinder stops, you will be unable to grind again until you click "Repair the Barrel Grinder's mechanism," which will use up 4 oil and 4 leather from your inventory.
The trick to doing this efficiently (not wasting a ton of leather/oil on repairs) is to keep the grinder running as long as possible. There are three primary ways to do this: get a lot of people to help wind up the grinder, get some good +end food, or a combination of the previous two.
Obviously the more people the better, but just from looking at the numbers, you would probably need at most 7 people to keep the grinder going constantly (one person winding every 18 seconds). If you had some grilled fish on hand, you would need at least 5 people (one wind every 19 seconds) for constant grinding. Even if you can't keep it going until all your metal is ground up, it's still a lot cheaper than doing it by yourself :)