First, progress through the story until you reach Jakob's Estate on the Eden-6 planet. This is late in the story. This farm is even better after completing the story and increasing the difficulty to Mayhem III. Even on Mayhem I, you will get a lot more high-tier gear. Go to the area with the elevator that takes you up to Jakob's Mansion. There is a bridge with a New-U Station (remember the New-U Station, as it makes the farming much easier). Make sure to activate it as you pass. Run into the area with the elevator to find a Loot Tink. The Loot Tink will always respawn, and there is a chance more Loot Tinks will spawn in the area. When you defeat the Loot Tink, loot the backpack on the ground for additional loot. After defeating the Loot Tink, exit to the menu and reload to respawn at the New-U Station by the bridge. Repeat this process as many times as desired. Legendary weapons are a lot more commonly dropped by Loot Tinks. If you play on Mayhem III, it is possible to get multiple Legendary weapons per run. It only takes a few minutes per run.