Yup, that's the tool, I don't know the name either, they showed us in a grading class how to use it.
here's how I understand checking; As the timber shrinks, the drying shell is shrinking around a still green and swollen core. When this drying stress exceeds the woods strength perdendicular to grain, it splits. Wood is far stronger with the grain than perpendicular to it. What I think you are proposing is that the wood is splitting diagonally across the length of the cells. The picture I'd like to see would be to cut a firewood length of the checked larch then to split the firewood right beside the check to show the grain orientation. I hope we can agree that firewood splits with the grain? I'll bet the check and the split is in the same plane, the wood will not split across the check.
That said I can think of a notable exception where I often see cross grain breaks at 90 degrees to the grain, across the board.
When we lay 5/4 southern pine decking. The decking is often made from heart pieces that include juvenile wood. When we screw the board down it is restrained from bowing. The mature wood alongside of the juvenile core restrains the wood also. It is pretty common to see an unrestrained piece on a pile bow like crazy. It is also common to see a piece screwed down on a deck checked, cross grain in the juvenile zone as that wood shrinks lengthwise. That is not what we're talking about here though, they are graded as "compression failures" or "timber breaks" and are limited to the lower grades.
What you are proposing would stand grading on its head, its opposed to I was taught in grading school and have seen in my experience. If you can get tension perp failures in the grain direction, we got biiig problems
That is another thought. How many are using accredited graders as required by code in most places? Should the Guild be having graders teach sessions at events? The '06 code has tightened up a notch on that front, that will only continue.
