FINALLY! the voice of reason. well said, Steve

dave

Steve wrote:

I have two 12" combination squares, a Starrett that I use for

woodworking, and

a Sears that I use for rough carpentry. The Starrett is square +/-

0.001" over

its entire length (90 degrees +/- 17 arc-seconds). The Sears deviates

from the

Starret by 0.011" along its length (90 degrees +/- 3 minutes 9

seconds).

For anyone keeping score at home, 99.9% of normal people use a speed
square for rough carpentry since they don't want to bang up their combo
square in a rough carpentry environment.

A marking pencil or knife is going to be significantly thicker than .001
rendering that sort of accuracy useless for woodworking. Additionally,
unless you're using a robotic arm to mark, the line is going to waiver
as your arm moves the knife or pencil. You can also add in blade
deflection, wood movement, etc. and figure out that .001 accuracy is
complete overkill in woodworking.

So get the cool .00000001 accurate tools if you want but please don't
think that they're going to do any better for you than a .01 tool.