Author Topic: I really wanted a yew warbow anyway  (Read 10673 times)

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Offline ScottRoush

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I really wanted a yew warbow anyway
« on: January 17, 2014, 04:57:04 pm »

 
;D  Now I get to start on my yew bow because it just arrived this morning!  It's Pacific yew and 74" long.  I'd love initial opinions on the stave.. and that bothersome (for me) knot.

Sorry for the crap pictures...









Such tight growth rings? Is it even worth trying to chase a ring??



And is that the cambium on the sapwood? I don't see any rings....


Offline WillS

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Re: I really wanted a yew warbow anyway
« Reply #1 on: January 17, 2014, 05:21:46 pm »
Sorry to hear about the Ipe bow.  Looks like it might have been too dry?  Hard to tell though.

Onto the interesting bit... 

That knot may or may not be an issue. It has got a ring of black gunk around it which might be cause for concern, but it's not in a dangerous place within the stave and even though it's poking through the back you SHOULD be ok.  However, you'll need to wait a bit to see how it looks as the bow starts to flex.  Or, I suppose, if you're super worried about it, give it a dig and see if it just drops out once you start removing the black stuff.  If it stays put and really won't budge, superglue.  If it falls out, do what I said in the PM and stuff the hole with a good solid mix of epoxy and yew sawdust, or even a Dutch Plug - make a long dowel of offcut yew and push it all the way through the hole where the knot was, leaving a bit sticking out each end, then remove the excess. 

Everybody you ask who knows their warbows will tell you to always chase a ring with Pacific yew, if you're aiming for something over 100# or so.  The sapwood looks a bit too thick from the picture of the end grain, so you'll probably have to reduce it anyway, at which point take your time and get down to a single ring but do it in stages. 

74" is just long enough to push a 32" draw with a heavy bow (what weight are you going for?) and it's also the absolute minimum length allowed in the EWBS. 

At this point, what I'd be doing is marking a center line, and drawing out your front profile bearing in mind what I mentioned earlier about Pacific yew - go slightly wider than dimensions of Italian yew bows - 40mm should be perfect.  You can find fairly rough dimensions in Secrets of The English Warbow, but you're basically after a long middle section staying around 40mm wide, almost right up to mid-limb.  At that point you should taper to 22mm thick tips.  Cut that shape out and use it as you're tillering, but bear in mind the final tip width should be around 12mm.  The wider you can leave the tips to start with the better, in case it wants to twist as you're teaching it to bend. 

Once you've got your front profile roughed out, reduce the sapwood.  You'll have a better idea of the ratios once the front profile is roughed out, so you won't need to spend hours chasing an entire stave - just the bit you need!  You then need to decide on a belly profile - avoid the D shape of Victorian bows and some of the Mary Rose bows, and go much squarer - a bit like a rectangle that has no edges.

Offline WillS

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Re: I really wanted a yew warbow anyway
« Reply #2 on: January 17, 2014, 05:30:48 pm »
This is a fantastic thread for a build along by the way - his bows are really nice and it's very well explained and written.  Lots of info on profiles, tapers, belly shapes and so on.

https://www.primitivearcher.com/smf/index.php/topic,863.0/nowap.html

Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #3 on: January 17, 2014, 06:06:16 pm »
Thanks for all the info.  Once again.. I'm off on my measurements! That stave is 77 inches.. not 74.

Thanks for linking that thread.. I've been searching for something like that.

You bring up something that has me thinking.. you mentioned my wood being too dry.  I heat my shop with a woodstove... and it's been bitterly cold for weeks.  I've noticed that all my dust catching buckets and slack tub are evaporating at alarming rates.   Nothing I can do about the ipe.. but I now have the yew to think about.  It came from a guy in California that is going through an epic dry spell... so I'm hoping there shouldn't be that big of a moisture change for the wood..... but would it be better not to keep the stave in my shop when I'm not working on it? 

Offline Del the cat

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Re: I really wanted a yew warbow anyway
« Reply #4 on: January 17, 2014, 06:25:45 pm »
IMO you need to get that knot out, but without damaging the sapwood end of it (that's if it protrudes to the sapwood).
If it just goes in sideways ignore all following referenceds to sapwood.
If it is visible from the sapwood side you may be able to knock it out. Basically you need to clean out the black manky stuff round the knot, that's the problem stuff, the knot wood itself is prob harder than the parent wood, but the black manky stuff has no strength and will compress probably causing a pinch.
If you can't see the other end of the knot it begs the question. What happens inside the wood?
If it was me I'd drill down the belly side with a drill a good bit smaller than the knot without going through into the sapwood or the parent wood (e.g just drill in the knot itself). Pick away at the remaining knot collapsing it inwards, clean it all out to solid clean wood (doing it this way leaves the wood fibres intact where possible for maximum strength) Pack it with a fairly dry Yew dust/epoxy mix this will squeeze out the hole in the back and show you have got a good fill. Once hard, you can then drill out a good depth on the heartwood side and glue in a nicely matching Yew plug.
IMO That's the most solid sound way of repairing it. You could just do a plug, but it's easy to end up with a cavity if you are not careful.
If you follow my blog from here, you'll see a HUGE knot on the side of a bow successfully filled and plugged. It shows why you need to see what's going on inside the wood.
http://bowyersdiary.blogspot.co.uk/2012/01/mystery-knot.html
Hope this makes sense and is some help.
It may be advisable to go for a more modest draw weight say 90 or 100 rather than going too heavy.
Del
« Last Edit: January 17, 2014, 06:29:26 pm by Del the cat »
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Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #5 on: January 17, 2014, 06:49:45 pm »
Great.. thank you Del.

Yes.. mine penetrates to the sapwood.  I should have explained that in the two pictures above. One shows the knot on the belly.. another shows the knot in the sapwood. Would I plug both sides?

Just curious... Once filled with epoxy/saw dust.. does the plug just become an aesthetic thing.. or does a plug of the same material as the bow behave better than the epoxy?

(edit:  yes... I'm aiming for 100 pounds on this bow.. if it falls to 90 I won't be heart broken.. just a tad disappointed.)
« Last Edit: January 17, 2014, 06:52:57 pm by ScottRoush »

Offline WillS

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Re: I really wanted a yew warbow anyway
« Reply #6 on: January 17, 2014, 07:17:07 pm »
As a side note Scott, how extreme are those tapers on the belly? The log has clearly been put through a bandsaw, and there doesn't look like much belly is left, but without references to size it's hard to tell.  The reason I ask is you might find that keeping a square cross section is tricky and you might be forced to go slightly more triangular than is ideal - in which case dropping to something under 100# would be wuse to avoid excessive set.  I may be wrong though and you may have enough width/depth.

Basically, could you fit a 40mmX40mm square in cross section smack in the middle of the bow, or do the sides drop away too drastically?

Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #7 on: January 17, 2014, 11:30:48 pm »
Oh I should be fine with 40mmx40mm.  But I was surprised at how reduced that stave already was when I got it.  The other self bows I've made were basically from logs... osage.

Offline WillS

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Re: I really wanted a yew warbow anyway
« Reply #8 on: January 17, 2014, 11:39:39 pm »
Just means less work for you ;)

I remember buying a really stunning stave of European yew - one of those "one in a million" staves - and the guy who had split it on the bandsaw had tried to get as much as possible from one log, and the stave was so drastically tapered from back to belly that I couldn't use it all! Very frustrating!

Best of luck with this bow Scott, the stave looks great and with the experience on here you should be absolutely fine to make a good bow.  Post pics, ask questions etc!  I look forward to learning from your thread!

Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #9 on: January 18, 2014, 12:47:56 pm »
Okay.... quick question on the layout of this relative to that knot.  I'm assuming it would be best to just keep the knot centered and fill it?  It MIGHT be possible to avoid it.  You can see in this picture a string I've laid out.   The stave is 2 inches wide at center tapering to 1 inch at tips.   It is 1 3/4" inches thick. It has that obvious taper from sawing and the belly width is a little over 1 inch.

So.. is it worth trying to layout in a way that keeps the knot out of the picture?  I suppose I will have to experiment with sketching it out on the back to see if it's even possible..


Offline hankknickmeyer

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Re: I really wanted a yew warbow anyway
« Reply #10 on: January 19, 2014, 02:40:56 pm »
Hi Scott,
Looks like we both got excited by Mick's post on Bladesmith's Forum.  I dug out my almost finished osage flat bow and have some yew staves on the way.  I'll post photos when I have something to show.
Hank

Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #11 on: January 19, 2014, 10:11:11 pm »
Hi Scott,
Looks like we both got excited by Mick's post on Bladesmith's Forum.  I dug out my almost finished osage flat bow and have some yew staves on the way.  I'll post photos when I have something to show.
Hank

Ha!  That's great.  Amazing how inspiration strikes like a lightning bolt eh!?  Can't wait to see what you come up with....

Offline Del the cat

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Re: I really wanted a yew warbow anyway
« Reply #12 on: January 20, 2014, 09:31:38 am »
Great.. thank you Del.

Yes.. mine penetrates to the sapwood.  I should have explained that in the two pictures above. One shows the knot on the belly.. another shows the knot in the sapwood. Would I plug both sides?

Just curious... Once filled with epoxy/saw dust.. does the plug just become an aesthetic thing.. or does a plug of the same material as the bow behave better than the epoxy?

(edit:  yes... I'm aiming for 100 pounds on this bow.. if it falls to 90 I won't be heart broken.. just a tad disappointed.)
Short answer I don't know.
Long answer, I think a plug of the same wood will be a better match in terms of compression characteristics.
An untreated knot is like having a hole in the bow with a loose bit of steel plugging it, the wood will collapse until it hits the steel and then bind up solid, thus it creates damaged wood and then overstresses it... great recipe for failure IMO.
Del
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Offline ScottRoush

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Re: I really wanted a yew warbow anyway
« Reply #13 on: January 20, 2014, 09:52:43 am »
r 100 pounds on this bow.. if it falls to 90 I won't be heart broken.. just a tad disappointed.)
Short answer I don't know.
Long answer, I think a plug of the same wood will be a better match in terms of compression characteristics.
An untreated knot is like having a hole in the bow with a loose bit of steel plugging it, the wood will collapse until it hits the steel and then bind up solid, thus it creates damaged wood and then overstresses it... great recipe for failure IMO.
Del

Thanks again Del.   Does my last post make any sense? I mean... does it make any sense to attempt to profile with the knot out of the picture?  I suppose it might be hard to answer given that you do not have exact coordinates of the knot.  But I dunno... I guess I should just go with my gut and center that knot and fill it... I have a feeling it will be fairly small by the time I remove the belly wood....

Offline Del the cat

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Re: I really wanted a yew warbow anyway
« Reply #14 on: January 20, 2014, 11:56:49 am »
There is no right answer, until you do it and it doesn't explode. :laugh:
I'd favour a longer bow with the knot still there, but try to lay the bow out so that you loose as much knot as possible, but also so that the small hole in the sap wood doesn't end up hanging off the edge of the bow. E.G I think the best place for the sapwood hole is dead center as near the grip or tip as is possible.
If the sap wood hole worries you, it is possible to patch over it, but I think you should be ok. That's prob a last resort if you find there is a big rotten hole and the sapwood is severely compromised.
Some times I go to the trouble of filling a knot to find it's all disappeared ehren the bow is finished, but I'd rather do that than suddenly expose a pocket of rot right at the end of the process.
Del
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