To thin, or not to thin...

[WillS]

I've just come across the most insane piece of yew I've ever seen - 83" long, dead straight, slight reflexed tip, well seasoned, about 60 rings per inch - which is hopefully going to become my dream warbow.  I have one question though - on one side, with the bark removed, the natural thickness of the sapwood is 1/8 inch which is perfect.  The other side is thicker though, ranging from 1/8 right up to just over 1/2 inch thick at one tip. 

Do I chase a few rings down to get a better ratio on the one side, risking the perfect side, chase the rings at a slope leaving the good side the sane while reducing the thick side, or just leave it as it is?  The way it's looking if I leave it alone one tip will be almost all sapwood.

[BowEd]

I would guess your stave is from a trunk.Probably does'nt mean anything but my choke cherry I just finished had a big difference like that too from TTT with the thicker sapwod tip being the bottom of the tree.I left it be as is with no ill effects.Decisions,decisions,decisions.......LOL.

[BowEd]

There is'nt as much work being done towards the tip.Might be a personal preference thing in the end but good luck with it.

[adb]

When I'm making a yew selfbow, I start by trying to get the sapwood a consistent thickness from tip to tip. I rarely bother chasing a single growth ring on the back either.

[WillS]

When I'm making a yew selfbow, I start by trying to get the sapwood a consistent thickness from tip to tip. I rarely bother chasing a single growth ring on the back either.

Yeah generally I do the same.  I've never had a stave this nice before, that's all.  Chasing a ring increases the chance of making a mistake, and part of me wonders whether it's just an aesthetic thing right at the tips, or whether performance will be affected.



This pic shows the tip on the side with the thinner sapwood



And this is in the exact same place, with the stave flipped over.  Same tip, much thicker sapwood. 

[Carson (CMB)]

I would leave it as it is, personally.  Shape the tips with more thickness and less width, if you want to keep heartwood on the tips.  What is your target weight?

[WillS]

Somewhere between 100 and 120#.  It's a bow I've wanted to make from the moment I started making shavings, and I think this stave can handle it, if I'm slow and careful enough!

[Joec123able]

All I have to say is good luck, hopefully you can get your dream bow from it !

[ravenbeak]

I would definitely thin it down to try and get even thickness throughout the length of the stave.

Try to minimize ring violations but dont overstress about it.

Good luck!

[coaster500]

I would definitely thin it down to try and get even thickness throughout the length of the stave.

Try to minimize ring violations but dont overstress about it.

Good luck!

X2.............The man knows Yew

[WillS]

The only reason I'm wary of thinning it, is because the sapwood is so uneven across the back.  If I were to make the sapwood 1/8 thick on both sides, the back would be slanting at an almost 45 degree angle.  With yew of this quality I'm really not worried about violating rings this close to the nock, but having a slanting back makes life very awkward from previous experience!

[Hamish]

The photoVirtually all the old, late 19th and early 20thC yew bows that I have seen had the sapwood trimmed across the width of the back, but broadly followed along the length of the stave.One side could have virtually no sapwood at several spots( I would at least have 1/8"), maybe 1/2" on the other side, or anywhere in between.Admitedly they weren't warbows, but ranged from 1-1.25" wide at the handle.
60rpi is pretty good, I reckon you will be fine if you apply common sense.
                                                                                                               Hamish.

[WillS]

Hopefully this will make it clearer! This is the view of one end, and the angle of sapwood gets gradually less as it goes down the limb, where it's back to a flat even ratio near the middle

 

Now, if I were to thin the thick side so that it matched the thin side, I'd be left with one limb essentially propellor twisted as a result of the back being so uneven.  That would then require heating and streaming to resolve which is exactly what I didn't want to do on a piece of wood like this!

[Del the cat]

Been there, done that  .
There is no 'right' answer.
IMO the simplest is to leave it 'as is' with it thicker one side.
If you follow a ring you are asking for it to twist, and you will end up with a very skewed profile.
Of course you may have to compromise a tad to avoid all sapwood at the tips.
There are some posts about this very thing on my blog... I'll try and look 'em out for you.
http://bowyersdiary.blogspot.co.uk/2012/04/weird-heartsap-boundary-emails.html
http://bowyersdiary.blogspot.co.uk/2011/04/different-approach-to-twist.html
To add to the confusion, the heart/sap boundary doesn't necessarill follow round a ring anyway.
If you are going by Mary Rose dimensions, you may find that the wider profile with late taper to the tips helps stop twist. However I'd still advise leaving the tips full width at least until you hit brace as the wider than deep profile will help avoid twist.
Good luck
Del
BTW I generally work the sapwood down in stages, so it will be roughed off with a drawknife if it's much too thick and tided up with a spoke shave to vaguely be all at about the same ring... ish. As the bow progresses I'll work the back down getting closer to the final ring or stepping up/down a ring if I have to, but blending it in. This will have about 3 stages of tidying up until it all gets finished in pace with the rest of the bow.
That way it's not such a chore.
Another good tip is leave extra sapwood at the tips and/or glue on temporary tip overlays (high viscosity superglue will do it) to take the strain and protect the sapwood.

[WillS]

Hi Del, thanks for the reply! One of those links I was actually checking out earlier, the approach to twist one.  I wonder how much of this is about aesthetics as compared to performance.  If the horn nock takes say an inch out of the tip (normally I only make them half an inch deep) and one side has perfect ratio, I can't see a couple of inches of next to no heartwood right at the tip making much detriment to cast.  But of course it won't look very pretty, being all sapwood. 

Although it could be a diva bow and have a "best side" for photographers ;-)