The last couple of weeks I have been setting up a steam box that was long enough to heat and straighten two of the spars from Air Craft spruce. One spar was out by 1/4" and another was out by 1/8". Not too much but it bothered me as I wanted the spars straight as possible before sliding on the ribs.
I used masons string pulled tight at the end of the big jig table to check the curvature in the spar and as a guiide when pulled back straight after steaming.
