Originally Posted by hs_300e

Check out http://www.boltdepot.com/fastener-information/Default.aspx - all you wanted to about bolts and nuts is in here.

The following page - http://www.boltdepot.com/fastener-information/Printable-Metric-Thread-Gauge.pdf - has images of various metric thread pitches. When you print it, the images are printed to scale. So you can very easily compare your bolt's thread pitch with the print out.