Been doing some thinking on this springboard thing.
So, you have a normal 2X piece of wood. They're extremely rigid and strong on their side, but show far less dimensional strength across the grain on the widest 'flat' side.
Add defects like knots, severed grain, shake, etc -- and they become even weaker.
Now, Great-Grandpa wasn't no dummy. Modern folks would have us believe they were a bunch of knuckle-dragging Neanderthals -- but these same guys were building 300 year structures. . . Out of wood!
Now add a taper, properly cut in, and with some thought (especially on 1/4 sawn wood) -- you've removed some of your cross-section, lost weight, but you've also added what?
Anybody? I don't see any hands raised, so I tell you what I see. . . A radius or arch.
Now, to anyone who has studied structural members, knows them dern Romans were bad mama jamas when it comes to modern architecture. They done figured out, before christ was a lad, that the arch is a super structure for strength. They actually figured it was a circle that was the strongest, but you could use sections of a circle and get good results.
I personally think correctly adding a taper to your board will add strength, and not take it away.
Thoughts?
opcorn: