Michael Dahl 
Electric Claw [PDF ebook] 

Sarah receives a package in the mail from her recently deceased grandfather: a life-size robotic version of him! Sarah enjoys spending time with robo-grandpa, but her mum thinks the invention is creepy. One night while Sarah sleeps, her mum sends the robot to the scrap heap — leaving only one hand behind. Sarah holds on to it as a memento of her beloved grandfather — but like Sarah, the hand has problems letting go . . .