Questions? 1. Low rpi Yew. 2. Yew ring violations

[Japbow]

Ok. If you want a 150# warbow you're gonna need some high rpi yew...of course.

What I have access to is more in the 5-20 rpi range. I assume that this is sufficient
for bows with draw weights of 40-60# while still getting the excellent tension
and compression attributes of yew, right?...or perhaps I'm wrong!?

I've made one shorty elb style (out of a branch) which started out 65# at 22",
49" ntn which shoots fine. (I later re-tillered down to 55# because it was killing
my shoulder)

Also, I always silk back my bows just for a little added insurance!

Would I be goofy to try to get a decent flatbow or elb bow from yew with the
below stats  at around 10 rpi???

                    60" ntn, 55# at 26"

One more yew question...

I've kinda gotten the vague idea from various sources that yew will tolerate
minor ring violations in the sapwood when thinning it down.  Is this true?
I hope it's  true b/c I dread the idea of chasing one yew sapwood ring.
This is why I previously made a bow out of a branch; it already had a good
sapwood-heartwood ratio.

I appreciate any insight...
Thanks,
Japbow.

[mikekeswick]

You can make a 150lb'er from low rpi yew.
Low rpi yew really , really benefits from a good heat treating (make sure it'sdry first).
No need to back it with silk.
Yes it will handle a few violations but you should strive for perfection!

[Del the cat]

+1
IMO This ring count thing is largely nonsense. But a high ring count and dark heartwood looks pretty
I've ocasionally had a 'soft' bit of Yew which as Mike says benefits from heat treatment.
My Yew has varied in ring count and colour but I've found no consistent correllation between either of these factors and performance.
You can get two bits of Yew growing 100yards apart which look entirely different yet behave the same, or look the same but behave different.

'Violations' implies a brutal dissregard for the rings. Sometimes you may need to go across rings, for a variety of reasons (see below) but it should always be done reluctantly, with caution and trying to keep any violations running along or diagonally across the bow if possible. Try to keep an even smooth sapwood layer. The ideal bow has a nothing done to the back other than taking off the bark and cambium layer.
Common reasons for going through rings.
1. Heartwood suddenly swirls or dips (or you just don't have much of it! Following a ring would leave the stave with too much sapwood (I wouldn't want more than 50% sapwood)
The pic shows an extreme example (not recomended) on a 40 year old bow, where I had to step down through about 8 rings else I'd have had no heartwood left! Bottom line, is you can only use the wood that's there.
You'll waste your life if you wait for the prefect stave.
2. The heart/sap boundary doesn't parallel to the rings. You can make the back back follow a ring or follow the heart sap boundary, but you can't do both.

I suggest you ignore the opinions of anyone who starts by saying "I read..." or "I heard..."
If they've actually made some Yew ELBs then listen, but always try to become your own expert.
After all when a bow breaks on you, people who were all too keen to give advice, won't be queueing up to take the blame.

Your suggestion of a 60" ELB is a contradiction in terms. You want at least 70". Trying to make a bow too short for it's drawlength, weight and style is a recipe for disaster. If you only have 60" then go wide and flat, you'll potentially end up with a superb bow.
If 60# hurts your shoulder.. I dread to think what 150# will do to it
Del
(sorry if this sounds like I'm in 'grumpy mode' )
PS Google bowyers Diary if you want to see all my build alongs including the failures. Plenty of ELBs there with twists bumps bends and tricky sapwood... search for 'ridgeback' on the blog, that's an interesting one.
 

[Japbow]

First of all, Thanks Del for the well-thought out and detailed reply!

I think you've managed to dispel a few a few yew myths, there.
(at least in my mind!)
You seem to be the man with the experience so I'm not gonna
argue with you!

Secondly, I have NO plans or desire to make OR shoot a 150# elb!!
I was just using the example that high rpi equaled performance.
I guess that's not the case...but, I also agree that it does look pretty!

I misused the term "elb". What I meant was a "D" shaped cross-section.

I have a bunch of yew staves just waiting for some action but I wasn't
sure how to deal with the excess sapwood without possibly ruining them.
You've given me some peace of mind and confidence to proceed, for sure.
Thank you!

Oh, BTW, I check your Bowyer's Diary blog regularly. It's a great source
for inspiration (and a few laughs!).

Japbow.

P.S. Ever gotten your hands on some quality Japanese Yew?

 

[Japbow]

Thanks Mike!

I'm a realist with less than excellent draw knife skills!

[DarkSoul]

Since you're from Japan, I'm guessing you will be using your local species of yew, Taxus cuspidata? I can imagine there will be little, if any, experience with that particular species on this message board. You could run a search here; I seem to remember someone used some ornamental yew in the past... It's probably not too different from the other species, but it could still vary quite a bit. I personally think the European species of yew is generally a bit stronger than the north American species of pacific yew. I don't know where the Japanese yew would fit it, but I'm sure it'll make a good bow in the 50 pound range.

I personally do think the ringcount in yew is important. I've worked with 50 rpi and 10 rpi English yew, and noticed a lot of difference in how the wood worked. Both will make a fine bow around the 50 pound range, but the denser (=higher ring count) wood will yield a dimensionally smaller bow and is much better for heavy warbows. That being said, even 20 rpi (English) yew is good enough for a 120# warbow. Yew with a ring count of 5 rpi is probably a LOT softer than 20 or even 10 rpi. The softer wood gets damaged more easily when you use the bow for instance in the bush. I'd use the stuff with less than 10 rings per inch only for bows below 40#.
On a side note, yew with this low of a ring count is easy to chase a sapwood ring on. Get close to the ring with a drawknife, and then get the scraper to get to the right ring. It's OK if you violate one or two rings a bit, but ringchasing 20 rpi yew is really not difficult. I've also used a course rasp in the past, since this seems to take off the lighter colored earlywood from the dark latewood of the ring below it. Try it out on some scrap wood and see what tool you like best for ring chasing. Good lighting is important here.

As Del explained, the limiting factor in a yew stave is often the amount of heartwood. Especially on low rpi yew wood, the sapwood might take up half of the volume of the stave. It is your task to figure out how much sapwood to maintain. Even an all sapwood bow CAN be made, but I'd recommend to keep at least ½ of the thickness of the bow heartwood. Locate any defects and knots in the heartwood, and see how much good heartwood you're left with, so how much sapwood you'll need. I often establish the width layout first, before I reduce the sapwood.

Would you mind counting the number of annual growth rings of sapwood on your staves? I've found a consistent number between 11 and 17 rings of sapwood for English yew, regardless of the ring count (rpi). I'd like to know hoe much sapwood rings you have in that Japanese yew. Not that it matters for the production of a bow, but 15 rings of 40 rpi will of course result in thinner sapwood than 15 rings of 10 rpi wood.

[Del the cat]

Nope... never seen any Japanese Yew.
Del

[adb]

The only bow which had the sapwood chased to 1 ring was my 90# warbow. All the rest of the ELBs or flatbows I've made from yew, I ignored that, and just made the sapwood a consistent thickness. No problems. I've never broken a yew bow. Yew is amazing bow wood. It just begs to be bent, and is so amazingly elastic. I usually leave any knots on the back a bit proud.
Also, I haven't honestly noticed much difference regarding ring count. I've made bows with 20 rpi, and bows with 60 rpi, and I can't tell a difference.

[Joec123able]

I've never paid attention to RPI I don't see the significance

[PEARL DRUMS]

How many yew bows have you tackled Joe?

[Del the cat]

How many yew bows have you tackled Joe?

Bit antagonistic n'est ce pas?
Del

[PEARL DRUMS]

Not me Del, just curious.

[adb]

I've never paid attention to RPI I don't see the significance

Higher ring count yew is more dense. It should make better heavier bows, all else being equal.

Not to be antagonistic either, but how many bows have you made from yew? Is this like the one board bow opinion? 

[ionicmuffin]

so what your saying alb, is that if you use a low rpi piece you need it to be a bit wider to compensate for low density?

[adb]

No, I just make the lower rpi staves into lighter draw weight bows.