Primitive Archer
Main Discussion Area => Bows => Topic started by: wizardgoat on April 11, 2015, 01:52:44 am
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Been messing around lots with ocean spray, 3 OS bows so far.
On all the bows so far, Ive been getting weird little belly "cracks".
They're not actual cracks, they're there even before the bow starts bending.
They're always where a branch or twig is/was coming in from the side, also on little side knots, almost seems like there's some kind of ripple effect through the wood. It's only 1" diam
I know what a compression fracture looks like, and these are not them.
Like when you scrape over them, your scraper skips a little, and theyre tough to sand smooth
Anyone have any experiences like this? I'll be shooting lots of arrows out of it regardless.
I'll post pics tommorow
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Ive had them. They are annoying, and causes the draw knife to skip or dig deeper. Gotta rasp em and carefully sand. Using the finger-feel method of tillering on OS isn't always the way to go. (IMO)
I think they may be from the pith that forms on the smaller side branches, or the tangent rays/vascular bundles that are feeding the little side branches.
I worry about hinges near them.
I also discovered that OS sinks in fresh and salt water, even when fully cured. Not many woods in Canada with a SG over 1.0.
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I've had them too. I've always assumed it was me bouncing my scraper or something. Because I've done mostly OS (10 out of 15)I've assumed wood was just that way. I made a sanding stick with a piece of an 80 grit belt that I use to work them out. I pencil the area dark and then sand until the pencil mark is gone, Then continue scraping. I've never noticed that they were always by a knot but that makes sense. Probably just a little bend in the grain.
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Thanks for your input guys. This bows all finished, so I don't want to sand it.
I'm not worried about hinges on this one, I'll shoot the snot out of it to be sure.
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Sorry about changing direction guys but I was wondering to what degree the bark can stay on or if it needs to be completely removed?
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You can try to leave it on, I've had mixed success. A lot better bowyers than I have said that it's not if but when the bark will pop off. I think it depends on how much you bend it. If you make an 80" bow with a 24" draw length, the bark will probably stay on. :-\
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Well if you know anything about me they will BEND :D I really like the wood so far.
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Happy your liking the wood Jon, I forget when I cut your wood, but I'm 99% sure it was not the winter. Your bark will pop off as soon as you start bending it
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Ive only worked one OS bow, it had what your talking about. I used a sanding block and 50 grit to take the last pounds off so I would tear anymore out. Worked just dandy.
Jon my bark was looking just sweet!................right up to low brace. I pulled it 10-12" and CRACK! Ended up spending a good hour scraping it all off. Glad I did, now.
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here a couple photos. the pin knot/cracks really showed up after the stain job and finish, arghhhhh
some of these photos are of the same knot, just a different angle, tried to get as close as i could.
bow is rawhide backed now
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3816_zpslhdybcmd.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3816_zpslhdybcmd.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3818_zpsaoxgxlch.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3818_zpsaoxgxlch.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3819_zpstinghpr5.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3819_zpstinghpr5.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3821_zpsymxqh49l.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3821_zpsymxqh49l.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3826_zpsnreuwhys.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3826_zpsnreuwhys.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3815_zps4ssvetwz.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3815_zps4ssvetwz.jpg.html)
(http://i1370.photobucket.com/albums/ag255/wizardgoat/IMG_3823_zps1lu6msvm.jpg) (http://s1370.photobucket.com/user/wizardgoat/media/IMG_3823_zps1lu6msvm.jpg.html)
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Its a little tough to tell what is back, what is belly, and whether the belly is rounded slightly. Because you might have a couple things going on there. I haven't seen a pin on the belly that was an issue unless it is running across the grain and out the side of the bow. Those will often crack when heated or when the bow is eventually bent.
Often there will be a couple of pins that are spaced just far enough apart that a crack will develop between them. Depending on where those pins are it will be a show stopper for me.
The bottom line is that pins are a weakness, period. The question is, whether they are ideally located so not being over stressed.
Pins on the back or belly will often crack when the bow is heat bent either reflex or deflex, the heat basically is speeding up the inevitable. But depending on the situation it might not be a big deal or sinew or superglue take care of it no problem. I've had splinters lift at the pins on the back and so I always back any decrowned bow and some crowned bows depending on how clean.
You have to consider how deep a particular pin is and what direction, because you have to assume any crack that you can see eminating from it could be running the depth of the pin.
No one is going to know whether such and such crack is going to be a problem for that bow so I always assume the worse and over build, slightly. I don't finish the bow with a crack and I mark and watch it over time as I shoot it, then make a judgement.
I'm not sure what the results are of rounding the belly but my instinct is to flatten, at least. The bow I'm working right now is getting a concave belly, matching the crown.
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Steve, these are all belly shots and some belly side shots. Back is rawhide.
It's pretty flat belly, rounded corners. In a PM I mentioned I looked at them through a magnifying glass, and the cracks follow a little pith and disrupts the grain. Hmmmmm
I'll just keep shooting it!
Just curious. How many OS bows have you broke and why do you think?
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Steve, you making a Hollow limb bow?! Cant wait to see it.
Wizardgoat, I have had that same type of crack develop on an OS bow. I dint get out the magnifyling glass, and inspect it, but just assumed it was bad and did a patch with horn.
Looking back, I might just let it be and see how it handles over time if I did it again.
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WG, again, I don't want to sound like I have all this experience with OS or anything else, other than I've spent the last six months working diligently with OS in everyway and before that I made a half dozen bows, some being kid bows. I abandoned my OS longbow tradebow because of pin knots simply because I don't want to take any chances. I laterally wrapped those pins in 5 different places, with sinew, and I have no fear that the bow will never break.
I've never broke an actual bow that I felt was safe. I've never broke an OS bow or stave. I've only done some extreme bending tests, with billet type material, where splinters lifted in tension or extreme heat or quick drying caused pin knots to open or grain cracks to open. I fill them with superglue and ignore them, normally, or I laminate over them or back the bow or whatever. The only actual bow that I've I had a problem with was a rawhide backed OS longbow that lifted a splinter at a pin when the rawhide popped off in that exact spot. I would have had no problem laying that splinter down and rebacking it but instead I threw it in the fire.
I have a takedown molle OS bow that is decrowned and rawhide backed and it takes quite a bend and has been shot quite a bit and has no prolbems despite the pins.
But my point about the pins being weakness is that my bending test showed that cracks USUALLY develop at the pins first, sometimes quickly, long before the roughed up wood that is under tension begins to lift a splinter. And during the bending or, later, during the shooting, pins that are close enough together will share a crack. IF you try to work down through that crack you'll see it can go deep or that it will reappear during subsquent shooting.
The bottom line is that the pins are a weakness, just like any defect or knot or bug damage or rot is a weakness in any wood. I welcome that as it just makes the challenge to develop a successful bow even greater.
But as Carson said, in retrospect I might just let some of those defects alone and pretend they don't exist. For me it depends on the stress level in that area of the limb or whether I'm going to be 5 miles back in a wilderness on a the trip of a lifetime elk hunt.
So the bottom line is, I don't know. I'm just sharing my experience and thoughts. Its hard to argue with someone who has a violated bow that has shot 2000 arrows without issue. I'd rather not consider that the norm and instead go with the obvious--that pins break open in tension quicker than the wood, and then deal with them accordingly.
The defects in your pics are not as familiar to me. I'm a little concerned about the fish/football shaped ones. I can't really tell what is going on there.
We all need to break a few OS bows to really know.
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CMB,
Technically not really a hollow limb but just following the crown on the belly--concave. I did it with a rhody bow recently and liked it. Just makes sense. You end up with a lot more square footage of belly that way and, if you do it right, more even stresses across the limb, IMO. I'm in the the embryonic stages of experiment. But when I see where the stresses develop on high crown, flat bellies, I feel like dishing out the belly might be better.
But unless you use an electric router, god help you if you try to dish out a seasoned OS stave--do it when it is green.
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Thats where a limb came in from the belly side and the pressure from you bending the bow did a little seperating. I'll bet that all of your'lls bows that had this have been in the belly. All of mind were on the belly. Stress cracks where a limb came in from the belly.
I made 4 bows all had these. They never hurt any of my bows. Thats what I found out.
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It scares me only because it creeps up the side and that leads to the back. Id hang it up before it blows in my hands.
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Wizard, I've been in touch through about 50+ emails with Steve b. and have been invited to comment here though at first I was just going to watch because of my lack of experience with OS. I have worked 2 bows and can see and feel these weird wavy knots. I also believe that these are not compression failures that you have but believe they are expanding from heat and that's why they are there as you said before tillering...The 2 that I've worked and reported back to Steve had zero cracks in these areas but both staves never had any heat tempering or bending...Rich "half eye" has been shooting one of the OS bows I made and maybe he will examine it and chime in...I have mentioned to Steve b. that I think heat is the root cause for these little wavy areas that we call pins to expand and crack...So far so good with no heat...Just my 2 cent sir
Don
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Thanks guys. Yes heat has done that on another stave, but I used no heat on the bow. Pearly yes some of the pins went through to the back, that's why I backed it with rawhide.
I haven't blown a bow up in hand yet, gotta sooner or later. I'm up to a bit over 100 arrows out of this thing, I'll keep going.
This was supposed to be a gift for a friend, but maybe I should just make him a yew bow.
It seems like nearly everyone who has made an OS bow has noticed these marks, but no one has admitted to ever breaking an OS bow because of them. Hmmmmm
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I'm going to back up now that I've seen the pictures. I have not seen anything like that in the 10 or so bows I've made. Maybe I don't stress them as much as you guys. I am still a bit of a coward :D I'll try harder.
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over stressed don? i suppose. ;) its 60" 50# @ 28", stiff handle and less than an 1" wide... like i said though, these marks were in the wood before i started bending it. have they grown? its possible.
the only way to know is to put a bunch of arrows out of it.
i know theres not alot of documenting done on this wood, at least that i have found.
I'll keep track of my arrows, and let you guys know how she holds up,
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Just a thought....but is it that because ocean spray saplings are not split, it is the end of the grain where the wood spirals?
VMB
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Just to add another voice, I had an OS stave from four years back, develop what I thought was a typical chrysl during tillering and so I set it aside. But it looked and felt exactly like you've described. I may have to check it out again... I think its still in the shop somewhere.
Gabe
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I've had that happen a couple of times, haven't had any failures. Any bend tests on os for me tend to break in tension at knots while the belly wood remains intact, so I haven't worried about it. Interested to see if anyone else has had problems
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WG,
I haven't seen that before ( on OS anyway).
It's my theory that OS is weaker in tension than compression.
All my OS bows that failed during tillering had tension failure. Rawhide on the back should help.
Nice dye job btw. Due to the size of the OS stave I almost said it was rot. I still think they are vascular bundles that you have revealed by sanding. They seem to line up with the wavy grain/growth rings. The fact that they didn't take the stain/dye (water based I assume? ) further reinforces the Idea. I think they are Sclerenchyma tissues which are typically hydrophobic, hence no stain.
Anyhow, if you end up punching yourself in the face post the bloody bose pic. 😈