mirabai wrote:an an udder ting...
I can think of no reason to think that "most of the moisture is lost through the outer surface" regardless of boring. Definitely not my experience. It is demonstrated quite clearly every day in my shop that the wood dries, shrinks and otherwise moves more quickly and thoroughly after boring.
Tim B.
I agree with you Tim - note that when I said "most moisture is lost through the outer surface", I was referring to the case of a single narrow pilot bore. Once the chanter bore is roughed to size (i.e. step drilling and/or initial reaming), the rules change, because the surface area of that inner bore gets an order of magnitude bigger, and the newly-exposed wood surface is very nearly the final finished bore.
Another thing is that warping, and to a smaller extent shrinkage, is not just due to moisture loss; it's about changes in "residual stress" in the wood. When you cut away parts of a piece of wood, you change the balance of those internal stresses, and it can take awhile for them to re-equilibrate. I believe this is why a chanter can warp in the aftermath of reaming even if the starting blank was at equilibrium with the surrounding humidity.
As for boxwood, it's famous for warping. Some of this may be due to moisture loss, some due to residual stresses from "tension and compression wood", and I've heard that the application of modest heat can trigger dramatic warping in boxwood that was otherwise long seasoned.
As Tim says, I see little harm in a banana-shaped bore provided the cross-sectional area has not shrunk; the problem is that curvature of the bore makes it impossible for a reamer to cut accurately. If the warping began during the reaming process, then my guess is that the internal bore doesn't match the reamer very exactly at the end of the day.
This *might* be seen as an argument against re-reaming of boxwood bores, whereas for materials like ebony, reaming in stages over a long time is usually considered good practice. If in order to avoid the "crooked bore" problem in boxwood, one decides to ream more or less in one go, I would still think it wise to step bore early and leave the maximum time between step boring and final reaming, and hope that any warpage during the "settling time" between step-boring and reaming is small enough that a straight bore can be cut by the reamer, without excessive flexing.
Bill
