"A relic from the Progressive Era, Big Bertha promises a whopping x12 for any ore through it. Bertha doesn't like repeat customers."
The Big Bertha is a Reborn-tier upgrader. It was added in the Secret Update and is one of three (supposed to be four) secret reborn items that were added during this update. An Ore Cannon is the most popular way for the ore to be upgraded. For good aim, place the Big Bertha 9-12 units on the grid away from the ore cannon. However, some mines can drop ore directly into the upgrader. Ore can only be upgraded once by it because it "doesn't like repeat customers," but would certainly work twice with a Tesla Resetter, and 3 times with The Ultimate Sacrifice or the The Final Upgrader.
- Using any ore elevating item (Large Conveyor Ramp, Ore Hoister, or Ore Elevator) and an Ore Transistor, Alien Relic or a Diamond Egg can also be used as a method to get ores into the Big Bertha. This method is much more reliable than the Ore Cannon, and takes up less space.
- The Big Bertha (AKA Bertha the Fat) was an enormous German mortar, which was used during the First Great War. It was made by the famous Krupp industries, in Germany.