Robot Parts is an optional quest in Torchlight II, which spawns through three Acts. It begins when the player collects the first hidden piece of a disassembled robot.
You found a strange piece of metal that appears to be some part of a robot. It has '4000' carved into it. You wonder just how many more pieces there could be.
The robot parts are found throughout all acts of the game, usually on the last level of a secondary dungeon that has a cave-like appearance. There are some requirements that need to be fulfilled before the path to the location of the robot part is opened - like lighting all the braziers, exterminating all the roach eggs, etc. It must be noted that the entrance to the secret secured area within each dungeon area can appear at numerous sites, depending on level design.
Location: Widow's Veil is found inside Crows' Pass.
Requirement: Light all the Braziers.
The secret room is usually right behind the sitting Finnas, next to the red Portal to the Surface at the end of the instance, but can also be somewhere in the middle of the path through the dungeon.
Hang a Bell (quest item) found in the Blightbogs to summon Cacklespit and complete her Cacklespit's Brew quest (optional quest). The bell can be found in the Rot Gardens - it's near a post in the ruins. The place to hang the bell and summon Cacklespit can be found South East of the bell's location (Where to hang the Bell is most likely random, SE, NE of the Bell's location are most common).
After completing Cacklespit's Brew quest, you must return to the Imperial Camp to get new quest Fade's Passage from Widget (middle raccoon near exit) to talk with Fade in Sundered Battlefield. You will get access to them after "Some Assembly Required" quest. His quest Cacklespit's Realm will have you collect four heads of fallen champions in that map.
Upon completing Fade's quest, he will allow you into Cacklespit's Realm.
Requirement : Destroy all (6) tree trunks in Cacklespit's Realm. After doing so, an area that was formerly a dead end, located in the lower right island - when approached - will open up a secret path to where the head is. (May have more than one location. For me it was the upper left island, near the Fade and portal to Cackelspit boss fight, the path was in the upper right part of the island.)