Having struggled with the sloping sap/heart wood boundary on the last bow (see lower cross section) I thought I'd take the opposite approach on this next one.
The wood is the sister stave to the 'Recalcitrant Yew' (see the entry 6th January 2011), the heartwood is exceptionally dark and fine grained, and this stave was chosen by a chap who accompanied the lady who had the recalcitrant bow.
By the way I've since heard that it's performing admirably and she's very pleased with it.
Anyway the stave has a similar problem to the last bow I made, that is the sap wood appears much thicker on one side of the bow than the other, rather than slavishly following a growth ring and having the back of the bow sloping at 45degrees I shall shape the back to fit nearer the ideal contour. I shall still follow the ring along the length of the bow. Hmmm, maybe a picture is worth a thousand words.
I hope the picture makes sense, curved line at the top is our frame of reference which corresponds to the majority of the bow.
It is possible to correct a twist with heat, but it's difficult to clamp a bow tight enough as the stave is only an inch or so thick, and it's tricky to apply twist without adding unwanted bend.
Whereas there's plenty of length and leverage available when bending along the length of a bow.
The amount of twist shown is fairly typical in a stave and isn't really a problem, it's just a matter of deciding how you want to tackle it.