On Aug 22, 12:15*pm, Bob Kuykendall wrote:

My experience, backed by template checks on a variety of sailplanes,
is that getting the waviness below .004" is a lot more important than
making the airfoil exactly match the intended contour.

And after about a half hour of gauging the spar dips and bumps on
ships at your local airport, you can give the gauge to someone else
because you'll be "calibrated". A 0.006" wiggle is quite noticeable
by hand. 0.003 starts to feel pretty smooth.

-T8