[English Longbow] Yew Longbow: Ratio of heartwood to sapwood

washyew

New member
Hi all,

I have been building my pacific yew longbow and have pretty much gotten it into its rough final shape. I have been scraping away at it's heartwood to lower the draw weight and I have noticed the sapwood is now a great portion of the thickness.
Is there a general rule for the ratio of sapwood to heartwood?
Thanks.
 
D

Deleted member 7654

Guest
Generally you want the sapwood to be about 3-4mm but that's in an ideal world.
Often the sap/heart boundary doesn't follow the rings and you may even find that on one edge of the stave it's about 2mm and its 5 or 6 on the other.
Google 'Bowyers Diary' and you'll see the bows I've been making. A few posts back (about a week ago) you'll see one with that very problem.
Here is one post which shows the sort of problems you can encounter.:-
http://www.bowyersdiary.blogspot.co.uk/2012/04/weird-heartsap-boundary-emails.html
Bottom line is sometimes you have to reduce the sap wood and even go down through a few growth rings anong the length or width of a limb.
In theory violating growth rings is a bad thing, but a lot of that opinion comes from people working with Osage where it is vital. Yew can withstand some careful and gentle grain violations as the difference between the early and late groth is less pronounced (maybe because it's evergreen?)
I've had areas on bows where it is over 50% sapwood in places, but generally you want less than 30%.
Del
 
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