When doing mechanical design work, it’s pretty hard to avoid speccing screws for a design.  I don’t really remember the dimensions for metric screws so I am finding that I need to look them up all the time.  I’ve found a very useful site for this (link below).  It’s got a nice diagram telling you which dimension is where and it’s got values for:

  • Nominal Size
  • Thread Form Type
  • Major Diameter
  • Pitch
  • Root Radius
  • Pitch Diameter
  • Minor Diameter (Male Thread)
  • Minor Diameter (Female Thread)
  • Thread Height (Male Thread)
  • Thread Height (Female Thread)
  • Tap Drill Diameter

Link: http://www.newmantools.com/tech/threadm.htm

Update 24 Sept 2011: Added info about screw head dimensions