Screw 
To dream of a screw implies that you feel insecure with your performance or used by somebody for his/her benefit. It may also signify that you are forgetting about some important and necessary aspect. Then again, it may represent the act of sex.
Screwdriver
To dream of a screwdriver signifies your desire to repair a damaged situation or relationship. It may also represent a person in your life who needs your help to deal with certain issues.
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