Primitive Archer
Main Discussion Area => Bows => Topic started by: simk on June 03, 2018, 12:48:35 pm
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Ok, roughed out a new stave - found a big knot/branch 6" after the fadeout - it's still 1 6/8" wide at this point.
Will there be a bow or should i rather burn this piece of wood and grill a sausage with it?
Edit: How much sapwood do i need above the branch on the back to make a safe bow? Do i have to remove/extract this branch? How to deal with that spot?
What would you do?
Cheers
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Unfortunately with that branch running through the stave it think it will cause problems. Instead of making firewood cut the stave at the knot and save the long half for a billet to be spliced to another piece.
As far as cooking with yew I would suggest you not do it. Yew is toxic and could poison you.
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yes we want to avoid any bow relatated illness,, (-S hickory is a better cooking wood and not as expensive,, :)
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Thanx for fast advice.
Grabbed another one 8)
After three broken bows in a row my stats are in the basement so I cannot risk anything!
Cherrs
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Next time allow a little more wood in width when you are rough sawing. Even if the knot had been smaller you really didn't leave any extra width. The sapwood looked fine on that one, I wouldn't have touched the back. Save the good half for a billet.
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Is this stave maybe the second billet?
How can I cut an accurate splice? never done...do you cut free hands DC or do you have a special device? do you steam the splice for better fitting?
Cheers
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I use a band saw. Draw the splice on the back and then free hand it. The cut down the center is the most important, it must be straight. The other two can be finessed a bit. I boil and clamp them if I'm not happy with the fit. Yew works really well for boiling and clamping because it's soft enough to crush together nicely.
Where would that knot be in the bow? If that's in the handle or thick fade area it might work but if it's out in the limb by the time you tillered it a bit you would have a knot right across the belly, not good.
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So,
since I was here last time, you did lot's a work - congrats and thanx for presenting those fantastic bows, DC, Weylin, bushboy, TorstenT @ all the others...
Now I have some new staves in the works and a new question:
The stave below should become a recurved flatbow, Weylin-style, without triangels (-;
Now the width is about 1 6/8 and thickness is about 7/8 and there still is almost no bend - I assume, that in the end thickness will be max. 5/8.
As I have relativly thick sapwood - about 3/8 (9-10mm metric) - there won't last too much corewood in the end. I therefore was thinking about reducing some sapwood and take down some rings.
Do I have have to reduce the sapwood? Would you?
Could I also decrown the stave? Is this an good idea with yew? Has anyone decrowned a yew stave sucessfully? My idea about decrowning is, that with a flatter back I could take full/better advantage from the flatbow design....(surplus I could avoid the pain of following a ring 8))
Thoughts?
Cheers
[By the way: The knot on the last last picture has already fallen away with reducing, the picture is from an earlier stadium - so don't care about this...]
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Nature has provided sufficient sapwood above that knot.
As it's on the side it's not too much of a problem. The important thing is to remove any unsound material that is round it, pick it out, drill it out, whatever, it's the black manky stuff or any dead wood that will just compress and cause a pinch.
Leave a bit of extra width there, but don't go mad adding extra thickness on the belly too.
Here's a similar one, that required an extreme amount of filling:-
https://bowyersdiary.blogspot.com/2012/01/mystery-knot.html (https://bowyersdiary.blogspot.com/2012/01/mystery-knot.html)
https://bowyersdiary.blogspot.com/2012/01/filled-knot.html (https://bowyersdiary.blogspot.com/2012/01/filled-knot.html)
Ah, I see I'm answering a problem that has been solved... ::)
On to the next question.
Yes reduce the sapwood, I generally like to have at least 50% heartwood.
Del
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Thanx a lot Del, you are confirming my worries....
What do you think about my decrowning reflections?
cheers
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I've made primitive Yew bows with a little decrowning, but you want to keep some sapwood right across the back, ideally follow a ring, but you can compromise.
Here's a pic of the back of my go to field bow "twister" (1 5/8" wide ) you can see I've decrowned it a little, but haven't gone through to heart wood.
Del
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Thanx again Del, I will follow your expertise and for sure I will supervise the thickness of lasting sapwood by continous measuring the amount of decrowning. have a lot of work to do...better start right now...first measure and note thickness all over the stave... cheers
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I am not very experienced with yew, but if the bending limbs have enough heartwood thickness on the belly, maybe the tips won't need much. If it is recurved and maybe treated with heat to hold the static recurve, as long as it is stiff enough, does it need the compression strength of the heartwood there?
Just something to think about...
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Most of my yew bows are about 7/16-1/2" thick (10-12 mm) for the last 7-8-9". Those are guesstimates. They are all about 40#. If you're in that range you won't have much(if any) heartwood left without reducing the sapwood.
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thanx for your opinions...already 3 rings (and only 1mm) decrowned, ring by ring, couldn't wait :BB
almost completly flattend there will be enough (5mm) of sapwood. lets see. cheers
springbuck: if i did not reduce i would end with 2 or maybe 4mm of heartwood, of what i had a bad feeling and it also didnt look too nice, imho
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Hi Folks
May I bother you again?
This is another stave im currently working on - it will be a bow for my wife - about 64" long and 30# strong/weak
Theres a knot...nicely centered and healthy wood it seems. I think the knot can take the compression and the grain on the back is nicely going around it on both sides.That's why I decided to more or less ignore it.
Was that a good idea or do I have to...
A) take out the knot an fill it with epoxy?
B) let this spot a bit stiffer?
Thanx for your advice.
Cheers and have a nice day!
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In the pic with the bark on it looks just fine. I'd have left the flow of sapwood round it just as nature had done. (If you needed to de-crown, maybe take the sapwood down a tad but try and maintain the flow).
Just pic out any many wood and use varnish or wax to stop moisture getting in. No point plugging it on the back as tension will just open it up round the plug, unless you do it for cosmetic reasons. If you want to strengthen it, you need to over lay a patch say about 3-4" long over the area... just like backing a bow.
Del
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Hi Del, thanx for you relaxed statement - i had only slight concerns about the belly, the back sure is strong enough for a mum's yew O:)
but what exactely does this knot in the back physically cause? does it make the belly stiffer? does it affect the ability to bend in a negative way? can I completly tiller it away? or will it overstress the back if i let it bend like the rest? ist the knot-wood harder and has less compression ability than the surrounding wood? questions over questions...cheers
PS: no need to decrown this one thickness of sapwood is just fine...
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The sapwood back is just there to stop it breaking. If you have a sufficient width of clean sapwood it's fine. Excess thickness will make it stiff there.
My pet hate is people who leave a knot proud on the back and then make it proud on the belly too, the end up with a series of stiff spots with weak spots in between.
I'd rather add extra width than extra thickness.
(On the belly side I try to make sure there is no weak material which will compress and cause a pinch.)
Del
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thanx for your guidelines - that helps a lot. i will keep it slightly wider in the process and let it just bend...love you all!
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I try and measure the width of the knot and add that to the width of the bow. If you look at the first picture you can see on the left hand side that you've cut off a bit of the wood that was swelling around the knot. If you are going to narrow the limb, narrow everywhere but around the knot. I soak the knot with the thinnest CA I can get. And be liberal with the glue. If you can get a little bubble of glue over the area it will stay liquid longer and hopefully soak in more. If you just put a little on it will harden right away and then no more will soak in.
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thanx for your sharp eye DC! the interesting thing is, that this is the stave from the very first pic of this thread; after narrowing to 1 1/4 and thinnening the ugly knot completely fell away - and yes, once again worked a bit too fast - just wanted to take another look at the stave to ensure if it's really a crappy one - therefore worked a bit careless and almost ruined it myself - good for my wife, she is getting a new bow now. cheers
Last question, assistance please: i've got my other yew stave prepared for steaming recurves. is 5/8" (14/15 mm) a reasonable thickness for bending? i never steamed yew before..
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Yew bends reasonably easy. If you have some scrap pieces it's probably a good idea to do some practice bends. 1/2" would be easier than 5/8". Round off any sharp corners to about pea size, steam for at least 30 min. 45 would be better.
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So, the knot-situation turned to a hole-situation (-; ialready had prepared the epoxy when remarked that it didn't change tiller despite the hole. So im not sure anymore if I should fill it. Filled with epoxy it would maybe safer and easier to tiller, Thoughts?
The bending job on the other project was easy and successful.
cheers
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Some people would kill for a bow with a hole in it. :D Need some measurements
Width at the knot and width 2" above and 2" below the knot.
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Not any expertise, but a "hole in the bow" would be neat! The other guys can give the expertise, but at 30-35#, it shouldn't cause any problems. Keep posting, I'm curious how it turns out!
Hawkdancer
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Yeah, a hole in the bow would be nice. But: I cannot follow anymore the rule, that the bow in that spot has to be wider the diameter of the hole...alredy narrowed it to much at the hole :-\
I still could do it - thicker - with an uneven thickness taper - in that spot. But: Del's pet wouldn't like that!
Will post measurmets for DC tonight, after work!
Cheers
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Dig out all the black manky stuff. clean up the knot (or shape a Yew peg) and glue it back in with the surrounding gap filled with epoxy/Yew dust mix. (Mix it with plenty of Yew dust, a bit drier than you think, as it gets wetter when compacted in.
If you make a peg you can have a nice rounded end protruding through the back if you want that sort of look :)
You do have some extra width there, so you don't need to go mad with extra thickness.
Del
(BTW.. when you run out of problems, that's when the bow is finished ;) )
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So, my unfinished bows are still causing problems O:)
Bow no 1 measurments for DC are (width/thickness in mm): 2" before knot: 38/21, @ knot 37/22, 2" after knot 35/18.
On the following pic you clearly see the extra wood @ the knot - obviously didn't follow the grain there...
As far as I understood Del's pet would go for a yew-plug. My decision-making is not clear at the moment but I still think it would be easier and safer to tiller with the hole filled (with a steady thickness taper). Therefore I feel a slight tendency to follow Del's advice. Altough I like the idea of a bow with a hole. Thoughts?
On bow no 2 I've remarked 2 bad pressure marks from the leather gloves I used as cushions between wood and clamps while steaming (pic 2). Next time I have to take clean leather pads without stitches and folds...Can I make them dissappear with steaming again?
And a basic quastion about bow no 2: I'm a little concerned because it seems to have become a rather stressed design with these recurves and with a bow length of 63". Do I have to worry about it(Edit: If I aim for 50"@27)? It's a perfect piece of yew, wide and flat, planned slightly working recurves... (pic 3 - with my coppices in the background )W()
Cheers, thanks and have a very nice day!
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I've made lots of 40# yew bows with 30mm wide limbs so I was thinking you could narrow the rest of the bow and leave the knot as is but now I see how short your working limb is it's making me re-think a bit. Del has way, way more experience than me.
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DC - hope I didnt confuse you with pics and questions from different bows in one post... the hole bow is pic 1 which is 37mm narrow - whereas pics 2 and 3 belong to the other, recurved bow -the recurved one is wide and without irregularities, 48mm-30mm...but indeed has quite short working limbs...let's see what happens.
But further narrowing could really be an option to consider for the hole stave, which has classic longbow design.
by the way: does anyone have a good www.adress for a metric/inch converter?