In a message dated 12/29/98, Brent Beach wrote:

>>On Tue, 29 Dec, David Sutton wrote:
>Here's the question: Any good suggestions for testing the
>accuracy of the 45 degree angle on the backstop I've yet to
>attatch? I know you can check the accuracy of a 90 by flipping
>your square over, but how do I find a true 45?

Two 45 degree angles, when flipped and butted, produce a
 straight line. >>

Yes, but, Brent, so do two 44 degree angles, or two 46 degree angles, or two
37 degree angles, or two 15 degree angles, or ...

Jeff Gorman's method:  Plane two angles, put them together and see if they
make 90 degrees.  Not as easy, but it works.

Roger Harrer
If it's any consolation, I thought of the same answer, but caught myself
before I wrote it down   :>)