Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on February 25, 2015, 08:45:52 pm
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This never showed itself until the second coat of tung oil. It's on the belly. Unfortunately being freshly sanded I can't feel any lump. I'm hoping that it's a leftover crack from bending the recurves. The little knot above the crack is the same knot in the other picture. The crack is just outboard of the knot. After I saw it I put it on the tree and pulled it 40-50 times and still can't feel a lump. Any prognosis? Is it a wall hanger?
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Looks like a chrysal to me. Sorry! Most likely the "beginning of the end" - but I have a couple that I have shot for quite a while with a belly chrysal.
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I'm of the opposite opinion; chrysalis are usually a lighter color than the surrounding wood.
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What was your heat source?
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DC,
Looks like the knot is on the inside radius of your recurve, I surmise that you have a fracture cause on the belly when you bent in your recurved tips. Even though it's on the belly it looks like a tension fracture to me. just one guys opinion though
rich
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Stress crack from reflexing imho
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Steam when I bent it but the limbs were at least 3/4" thick when I did it. I know now that that was a mistake. It did crack and split quite a bit, I thought I had tillered most of it off. It's been fairly heavily heat treated since to get the recurves to stay in. I knew I was in over my head but it turned out great but for this.
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The red arrow points at the crack. I'm optomistic, I'll call it a crack :D
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It kinda looks like the hairline Crack I got from bending my tips back,
although a bit longer. I think I know what I did wrong because my
last bow went smoothly. I don't think the first one i did was steamed well enough.
The wood cools on the exterior much quicker than the inside of the limb
and if I took a little too long on the form than it was just too
much for the cooled section. .. when I did my second bow,
my new steam setup was much more effective...
I inspected my hairline cracks with the limb un strung and again at 29"
on the tiller tree.. there was zero movement at it, I still call it a bow...
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I believe that if you clean it a little and flood with thin superglue you MAY be good. Thats because it will be in compression for the rest of it's life. If you do it now you might save the bow in the long run. Again just my opinion
rich
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Not likely to be a chrysal in that part of the limb. Most likely a tension fracture during bending. Do what Half Eye suggests and then wrap it.
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Here is a picture of a chrysal on one of the first bows I made as a comparison. It looked to me like the "crack" was below the area that you recurved. Could be a crack - but if it below where you recurved the tip, you can't feel it, and it doesn't open up when you stress it, I am sticking with chrysal. BWTH do I know? ???
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I would pint to the dry heat as the cause. Did you have the bow on a caul when you heated it?
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Looks like the same Crack I got when I heated and bent mine too fast. Not saying you did this but looks identical to mine.
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looks like a crack to me , not a chrysall.
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Looks like a lunar ring to me >:D
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That's a crack no doubt in my mind. The spot the crack is in is hardly doing much bending so I highly doubt it's a chrysal
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I would pint to the dry heat as the cause. Did you have the bow on a caul when you heated it?
Yes. The bow is 1" wide at that point and the caul is a 2x8, so 1 1/2".
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Thats a shame she cracked. I think that steaming could cause some issues as well, after all you are stretching the fibers either way.
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Ah, ship happens. I will try another one. I'll get it a little thinner before I steam in the recurves. I might use dry heat. When I steamed the tips on this one they pulled out quite a bit. When I heat treated them they stayed in a lot better.
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I believe that if you clean it a little and flood with thin superglue you MAY be good. Thats because it will be in compression for the rest of it's life. If you do it now you might save the bow in the long run. Again just my opinion
rich
I tried to flood it with CA but I think the tung oil has already filled the crack, it didn't look like any CA went in. I'll shoot it til it gets worse.
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Chrysals are usually straight and at an angle, look more like hairs, less obvious than that. I'd say that's a crack.
IMO a pathc would fix it, clean cracks on the belly aren't too bad as long as they are not buckling up.
Del
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Here is a picture of a chrysal on one of the first bows I made as a comparison. It looked to me like the "crack" was below the area that you recurved. Could be a crack - but if it below where you recurved the tip, you can't feel it, and it doesn't open up when you stress it, I am sticking with chrysal. BWTH do I know? ???
That's not a chrysal either ;)
That's a crack. Chrysals always run diagonally because of what they are, and are always lighter in colour. They also don't wiggle about and zig zag like that. Both images are cracks, not chrysals.
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Looks like a crack from the bending, if it's not to deep it will most likely be fine. As Gordon said, not likely to Chrystal in that are of the limb. Super glue and maybe a wrap ,not even sure that is necessary ,the pressure is pulling it together not apart if it is just a crack and I think it is. :)
Pappy
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That knot acted as a fulcrum and stretched her right out until it tore. That's a tough bend for anybody to make with any type of heat. I doubt it will go anywhere based on where it is located.
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I would pint to the dry heat as the cause. Did you have the bow on a caul when you heated it?
Yes. The bow is 1" wide at that point and the caul is a 2x8, so 1 1/2".
Steamed wood that is held under tension and then hit with dry heat does not like that. It's OK to just support the curve but not to try to get a bit more curve.
Personally I would skim off a bit of belly thickness on both curves and lay down a layer or two of thinner wood to replace it and then blend everything smooth.
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I'd learn from my mistakes, as I've made more than my share, and make another one. I wish I took my advice.
But...when I first started I'd try to rescue these problem bows with varying degrees of success.
Lay down some epoxy and wrap it with thread. Put more epoxy over the thread. hope for the best.
Jawge
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Thank everyone for the advice.
Jawge I have definitely learned something,"Don't try to bend big hooks in thick wood"
PatM I was seriously considering a patch as Del suggested but I like your idea better. It would look like I did it on purpose. You'll all have to keep a secret.
PD I did notch the caul to make room for the knot but maybe not enough. I do believe the knot had a bearing on this.
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Unless proven different by breaking news, THAT is a crack resulting from the recurving process. 3/4" is too thick, with any wood I know of. I have done this exact thing two dozen times, and it's an easy fix.
Get a plane, sandpaper, double cut flat file, and/ or scraper, and flatten the belly of the limb for a couple inches each side, flat LATERALLY, even, and long enough to matter. Then cut a 1/8" slat of something beatiful and strong, prebend it to the original curve with boiling, steam, or microwave. Glue it on and blend it with the limb./ Presto, beautiful overlay, and durable recurves.
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PatM mentioned a layer or 'two'. The crack looks like it's less than 1/16" where it comes to the edge. Could I use two layers of veneer or am I better off with one thickness. With one thickness I only have one glue line to screw up :-[
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I just mentioned multiple layers so that you could avoid having to heat bend a single layer. If you have a woodworking store that sells veneer scraps you can use those with little prep work.
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The tips and arrow pass are what was sold to me as Brazilian Walnut. I'll try and match that. At least in color.
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Here is a picture of a chrysal on one of the first bows I made as a comparison. It looked to me like the "crack" was below the area that you recurved. Could be a crack - but if it below where you recurved the tip, you can't feel it, and it doesn't open up when you stress it, I am sticking with chrysal. BWTH do I know? ???
That's not a chrysal either ;)
That's a crack. Chrysals always run diagonally because of what they are, and are always lighter in colour. They also don't wiggle about and zig zag like that. Both images are cracks, not chrysals.
Thanks for the lesson! Always learning ;D
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Most likely a crack and unfortunately it looks like the bow is working at that point so the glue won't work. You would be better to do as Pat says and to use an elastic wood
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Most likely a crack and unfortunately it looks like the bow is working at that point so the glue won't work. You would be better to do as Pat says and to use an elastic wood
This is a good question. I might have assumed it wasn't working, or wasn't working much there. My answer was based on assuming that this was a static or barely working recurve. Just glue, or too thin a laminate here is not going to fix it well. So, I guess you can make it static, but that takes out a lot of working limb. Hmmmmmm....
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You can use a long feathered out laminate in a working area safely. You're just mimicking putting down a few extra growth rings.
Here's a pic of a belly laminate covering a v-splice that feathers well out into the working limb.
(http://i399.photobucket.com/albums/pp78/pat_05/013.jpg)
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Most likely a crack and unfortunately it looks like the bow is working at that point so the glue won't work. You would be better to do as Pat says and to use an elastic wood
This is a good question. I might have assumed it wasn't working, or wasn't working much there. My answer was based on assuming that this was a static or barely working recurve. Just glue, or too thin a laminate here is not going to fix it well. So, I guess you can make it static, but that takes out a lot of working limb. Hmmmmmm....
It is a dilemma. As I said, I don't believe crazy glue will work, it never has for me in the past. It just doesn't have the compression strength of wood or the elasticity. It may be a static but that section of the limb seems to be working a bit to me.
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I have steam bent underlays? of Peruvian Walnut(it wasn't Brazilian) and will start to fix them in a few days. I found a Hardwood Distributors Association Webside and it says this about Peruvian Walnut
"Physical Properties: Medium bending strength and resistance to shock loads. High crush strength and low stiffness. Very good steam bending characteristics. A compact, elastic wood with good strength properties."
Sounded like what I was looking for and they are right about steaming. I like low, medium and high instead of a bunch of numbers.
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Peruvian Walnut is one of the only "tropical" woods that actually is what its name suggests rather than just being named for appearing like a more well known wood.
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The dust sure gets up my nose.
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You can use a long feathered out laminate in a working area safely. You're just mimicking putting down a few extra growth rings.
PatM, could you also mimick adding growth rings by reinforcing the back rather than the belly? For example with a good coat of strong flax feathering out on both sides? That would be a lot easier, and could keep the limb working.
Just asking your opinion.
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You can use a long feathered out laminate in a working area safely. You're just mimicking putting down a few extra growth rings.
PatM, could you also mimick adding growth rings by reinforcing the back rather than the belly? For example with a good coat of strong flax feathering out on both sides? That would be a lot easier, and could keep the limb working.
Just asking your opinion.
But then your "growth ring" would be violated at both ends
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You can use a long feathered out laminate in a working area safely. You're just mimicking putting down a few extra growth rings.
PatM, could you also mimick adding growth rings by reinforcing the back rather than the belly? For example with a good coat of strong flax feathering out on both sides? That would be a lot easier, and could keep the limb working.
Just asking your opinion.
The crack is on the belly.
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I got that it was on the belly. Rings are continuously violated on the belly so in itself that's not an issue. The point of mimicking a growth ring on the belly is to reinforce the bow and restore the balance between tension and compression. If the belly was weakened due to a crack, my reasoning is that you could make the intact belly wood interior of the crack take the compression load if you reinforce the back (you locally but gradually shift the neutral plane with a fiber backing). The net result should be the same as adding intact belly wood, but the procedure would be simpler.
As for violation of rings: it aint the violation per sé, but the angle of violation that matters according to Tim Baker. And glued flax threads aren't growth rings either. So its a bit weird to compare these.
You may or may not know: individual cellulose fibers are at most 25 mm long, even in wood. Wood fibers are merely bundles of stacked cellulose fibers held together by friction (and hydrogen bonds) in the lignin-hemicellulose matrix. So wood fibers, even on the back of a baby-bottom smooth growth ring, are continuously "violated" or terminated. The stacking holds it together. Just like with fiber backings, be they animal (sinew) or vegetal.
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You can't lay them down like mother nature though.
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Pat, that is good to know about P. Walnut. I bought some off ebay once and liked it a lot. It was like slightly lighter ipe.
Marc and Pat, Re: glueing fibers on the back. I don't think this is the answer either, and I wouldn't do it like joachimM is suggesting, but T.Baker did it in TBB, and I have used linen cloth patches just like this before. Once to arrest a fret, and a couple times to "put wood back". It works. I have even built up low spot by applying a 1" long patch with TB III, blending it with a scraper, attaching a 2" patch, blending, and then a 3" patch, which I combed out at the edges while wet. Then, I wrapped the whole patch with glued on linen thread. Those two bows are still shooting.
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This bow broke today. Not because of the crack on the recurve. I was having trouble with the bowyers knot slipping so I twisted a loop to replace it. I got the string a little short and the brace height went to about 8"(maybe) I thought I would pull it anyway. Stupid me. Big mistake. It popped a splinter about a half inch wide. My wife heard it in the next room. I tried to take a pic but it won't show. It was a good bow. I got 500 or more shots through it. I will definitely make another like it.
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i thought you were talking about meth and crack lol ;D