In the past, nigger was sometimes used as a synonym for "defect." For example, the May 1886 issue of Scientific American, page 308 said, "The consequence of neglect might be that what the workmen call ‘a nigger’ would get into the armature, and burn it so as to destroy its service."
Similarly, when performing shoddy but functional work, one is said to "nigger rig it," especially when duct tape is used in place of proper equipment. It seems that this usage is taken directly from the derogatory use of the word to refer to a black person. "Nigger it up" has been used to refer to excessively gaudy, non-functional decorations to automobiles to attract attention.
The term nigger was used in lumber mills until the mid-point of the 20th century. It refers to a device that turns a log while it is being stripped of its bark. This may be an off-hand reference to the prejudicial use of the word, as until the machine was invented, this was considered a job too dangerous for anyone other than a black man.