Primitive Archer
Main Discussion Area => Bows => Topic started by: snag on October 10, 2012, 02:44:02 pm
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I'm starting to try and make a bow out of a piece of yew that has about 1/2" of sap wood. I'm thinking of taking the sap wood down a little. Do you have to back yew if you thin the sap wood?
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Nope, no need to back. Reduce it to about 1/4", best if you can follow a ring, but it's not absolutely vital as long as you get ot smoothly blended in.
Most of my English Yew has sapwood that is too thick and I take it down with a draw knife initially, then as I work work the bow down to size it slowly gets tided up.
There are some good pics at the foot of this post from my Bowyers Diary showing roughing out a Yew stave for an ELB
http://bowyersdiary.blogspot.co.uk/2012/03/keep-calm-and-carry-on.html (http://bowyersdiary.blogspot.co.uk/2012/03/keep-calm-and-carry-on.html)
Del
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1/4" is a good rule of thumb. Some of my yew bows I take all the sapwood off, or leave very little.
The sapwood is a natural backing and if its not severely violated wont lift any splinters. Like del said just make them blend well.
Dels blog is a good read I recommend it:)
-Pinecone
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I've only build two bow using yew and both were good shooters. The ring count was so high that there was no way for these old eyes to fallow a ring. This is the back of my last one. took it down to a 1/4 inch as mentioned above. The stain really shows the violations. The bow was over 50 pounds and I built it for a 29 inch draw with out issue.
(http://i28.photobucket.com/albums/c210/coaster500/Bow%20trade%202012%20TG%20and%20PA/YewTradeBow2012015.jpg)
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Hey Coaster, that's a great pic :), nicely shows what is ok in the way of violaations in Yew, most of 'em run along the bow, or are just a small island. Nothing too extreme, it's hard to tale a pic that show is so well without the stain.
Del
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I just reduced the sapwood on a yew stave that had 1/2" sapwood. I've done it once before and it worked great, no need for backing.
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Remove the sapwood layer that is directly over the heartwood and all the rest can stay where it is. (And if you figure out how to do that, post a build-along!)
Del, Bryce, Weylin, and Coaster gave you the real story about reducing sapwood, but they forgot one important point....POST PICS as you go! Lots of us have no yew to play with so we have to get our thrills vicariously.
Good luck, buddy!
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Thanks guys. I don't see how anyone could see or follow a ring in the sapwood. So it is good to know that you don't have to!
Coaster that looks great! I'll have to stain it.
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Thanks guys. I don't see how anyone could see or follow a ring in the sapwood. So it is good to know that you don't have to!
Coaster that looks great! I'll have to stain it.
On some low ring count Yew you can follow a ring, and it's a good 'aim' it's just not essential (getting the lighting right to see 'em helps).
It's like those difference between thos beurocratic 'guidelines' and 'legal requirements'... mind, have you ever tried explaining that difference to a beurocrat?
They wanted to put speed bumps 10 yards from the end of our cul de sac a while back because "it's in the guidelines to have them every 30yards"... you'd need a dragster to do any speeding over that 10 yards ::)
Sorry I'm rambling now... if we get onto daft beurocrat storries this thread will never end ;D
Del
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Hey Dave, I am looking at piece of thick sapwood yew and asking myself the same question. I plan to reduce it and leave it unbacked, unless I deiced to go for higher draw weight. But in the back of my mind is Chet Stevenson's mention of a thick sapwood bow that he made. He took it to a shoot where it garnered lots of skepticism form his buddies, until he shot it. I guess it preformed just as well as any of the more traditionally accepted sapwood/heartwood built bows of his buddies. This story from the old bowhunter is the only thing that has kept my drawknife out of the sapwood on my stave in question...at least for now.
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The trick is knowing if there will be enough/any heartwood for compression when you get it down to your draw weight. The narrower and deeper the cross section the better chance you have but if you are going for a wider, flatter design you might run out of heart wood. My dad unwittingly did the same thing as Chet Stevonson with his yew longbow that he started and even with a deep and narrow cross section there was barely a sliver of heartwood as ou got near the tips. It shoots fine but it was a close call.
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Hi Carson, I have been thinking about Chet on this one too. I didn't want to take off much of the sap wood...just a little. Just didn't know if there would be a problem with this or not. I pulled out the infamous Stave Master (thanks again Keenan) and hopefully will find some time this next week to make some shavings. I'll post some pics if I do. I can use all the help I can get!
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I think on some yew its easy enough to take the sapwood down but some it would just be a nightmare.
If the sapwood is pretty even got for it but if its like this one its just too much hassle to get it even.
(http://i121.photobucket.com/albums/o218/dwardo/IMAG0228-1.jpg)
This bow shoot well and has little heartwood to speak off. Tim baker did some tests and commented that there was little difference between the sap and heart wood.
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Hey dwardo, you're just showin' off now... drool drool ;D
Del
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Hey dwardo, you're just showin' off now... drool drool ;D
Del
more like whimping out ;)
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The real "Spring" in yew lies in the heartwood.
The sapwood is worthless in compression.
But the heartwood is both excellent in compression as well as tension.
I have a few other things to say about yew and its use of sapwood, but I'm afraid it would cause too many arguments >:D so I dare not lol
-Pinecone
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I'm all ears.....
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Not looking for arguments but information is king and information backed with experience is gold, right???
Bryce why do so many builders use the layer of sapwood if the heart wood is a better choice ??? I've build a couple of Yew bows but worked the sapwood down as recommended for the backs of both. I've got a couple more staves maybe I could take a different approach and make one all heartwood.
????? I'm with Snag
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The real "Spring" in yew lies in the heartwood.
The sapwood is worthless in compression.
But the heartwood is both excellent in compression as well as tension.
I have a few other things to say about yew and its use of sapwood, but I'm afraid it would cause too many arguments >:D so I dare not lol
-Pinecone
Yeah, those medieval English bowyers were just plain dumb.
Del
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I'm with Del. It's hard to argue with yew sapwood holding beautifully up to 200lb warbows. I would find it hard to believe the heartwood could do the same even if you could chase the ring on a 60-70rpi stave. NA's took all the sapwood off because they generally used sinew and there is some people who have experienced the sinew separating the sapwood from the heartwood if not removed. I will (once my staves are dry) stick with sapwood backs.
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Before everyone misunderstands me and think I'm anti-sapwood. I agree the sapwood makes an excellent backing and is the best tension wood around.
Coaster, bc it's a good setup! And easier Lol yew is probably the best selfbow wood around (shush Osage snobs)
Back is tension strong and the belly resist compression. I know you all know these I just want to clarify. If you have a perfectly good stave with good sapwood just leave it lol don't ruin a good stave lol but if the wood was diseased or mared, I would say take it off you'll be fine.
Oh del, you misunderstand me:D them bowyers got game!
Eric, I'm sorry and I don't mean to offend but your only half right.
The NA's also made selfbows of only heartwood, and some also had sapwood but if they did it was a very small amount. There have also been European yew heartwood bows.
I didn't say the heartwood was as strong in tension, but it's still good.
And I've also read that most of those war bows only lasted so long before they broke, but that bit of info is from a not-so reliable source.
I will say that if you have an all heartwood bow and back with sinew and get the neutral plane as close as you can to the back. You have a bow that shoots like a dream :)
My thoughts on yew sapwood are hard to get across and explain over a keyboard. And w/o a chalk board.
If you disagree with me that's fine. But I really don't want this to turn into bickering. Seems to be a touchy subject.
Yew sapwood is good stuff, just not always neccisary.
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The sapwood is worthless in compression.
-Pinecone
I think its this statement that just kind of jumped out. I am pretty sure there are more bows out there that have a lot of sapwood and perform well. My last pulls near 50lbs at 28 and is only 60" long and has taken less than an inch of set. So i think "worthless in compression" might be a bit strong ;)
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I thought the back was not under compression. It is under tension. Yew sap wood is great under tension. So as long as the sap wood isn't more than the heartwood it should be ok. Right?
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I have a few other things to say about yew and its use of sapwood, but I'm afraid it would cause too many arguments >:D so I dare not lol
Bryce, I think it was this non-statement, statement that led us to believe it would be to your heart's content to see all yew staves and bows alike have their sapwood torn from their backs and burned at the stake ;D
Snag, if the sapwood is thick enough the outer third of a bow limb can be all sapwood and shoot just the same. Maybe this is what dwardo was referring to.
I just want to ad, I love the way yew sapwood curls out from under a spokeshave. It has such non-wood properties, it feels like butter as much as it looks like butter. I wonder if baker or anyone else compared specific gravity of sapwood and heartwood.
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I have a few other things to say about yew and its use of sapwood, but I'm afraid it would cause too many arguments >:D so I dare not lol
Bryce, I think it was this non-statement, statement that led us to believe it would be to your heart's content to see all yew staves and bows alike have their sapwood torn from their backs and burned at the stake ;D
Snag, if the sapwood is thick enough the outer third of a bow limb can be all sapwood and shoot just the same. Maybe this is what dwardo was referring to.
I just want to ad, I love the way yew sapwood curls out from under a spokeshave. It has such non-wood properties, it feels like butter as much as it looks like butter. I wonder if baker or anyone else compared specific gravity of sapwood and heartwood.
Butter! How dare you? I think of it as cheese myself, the sapwood is a nice cheddar or maybe an Edam, the heartwood is a dry old Parmesan ;)
I think that maybe the sapwood is more tolerant of violations and defects which makes it better than the heartwood as a backing. I wouldn't trust a heartwood back with a knot through it, but a sapwood back can stand it. (Just my opinion)
Del
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BURN THEM ALL!!! No I'm kidding lol
I guess I shouldn't have been so vague, I know better now lol
TBB4 page 57 has a good blurb about yew sapwood that's worth a read.
Also in TBB1 the chapter of western native bows by Steve alley, is one I've read backwards and forwards.
:o did you say cheese!
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Definately Parmigiano-Reggiano