Ben Jackson wrote:

Ok, this is a stupid question, but are the inside faces of a machinists
square supposed to be square, or only the outside faces? Or, put another
way, are the blade and base faces both parallel?

I've got the old "never take two clocks to sea" problem -- I've got two
squares and I piggyback them and I can see light between the blades.
So now I don't know which one is off...

If you measure the width of the base and beam at several places it'll
tell you if they are _not_ parallel -- measurements all over the place
will indicate that the edges aren't straight, measurements that trend
from one point to another would indicate a taper. About the only thing
that this won't pick up would be parallel but wavy faces.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com