Primitive Archer
Main Discussion Area => Bows => Topic started by: richardzane on October 29, 2015, 05:56:06 pm
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would appreciate a little advice
while heatgun reflexing a roughed out osage bow (stave seasoned 2 yrs) I find this parallel crack down the edge.
does this mean the bow is not worth messing with? kindling? or could it be packed with super glue clamped and saved?
any suggestions would be appreciated!
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Richard,
Open the crack... add super glue and clamp. I think you'll have a bow if the final design is not real aggressive. Meaning a little longer than ideal.
DBar
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fortunately it IS a 6 footer, but i was going to flip the tips...hmm, maybe not?
whattda ya think....back off and keep it simple?
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What draw length and poundage are you looking for?
DBafr
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While that crack may be repairable with glue and sinew, et al, if I had other wood available to me to use now, I would hold off on spending too much time with that one.
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Danzn Bar, I'm aiming to make it a 55#
RBLusthaus, I do have a mess of staves to choose from...it's just THIS one was turning out so beautifully :-)
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Richard,
It's good to see you back on PA...it's been a while, I remember a very nice persimmon bow you posted a couple of years back.
What draw are you looking for? 55# at 28"? IMHO I would glue and clamp, and make the bow 68" with an 8" static handle and flip the last 6" of the tips up a bit. With a good glue joint I think you will be fine. Remember it's osage.
DBar
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That is one strange crack. I don't think Ive seen one like that occur while doing what your doing. Makes me think your wood isn't dry enough for heat yet. The years matter not, its all about what RH its been stored in and for how long.
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Oh, and it looks like your trying to shape an 80-90# bow. Get that baby bending nice and even on the floor at about 60-70#, then put the coals to it. It will hold more shape, straighten and bend easier, i.e. less cracks.
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it looks like the wood may have been a little thick,,?
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That is one strange crack. I don't think Ive seen one like that occur while doing what your doing. Makes me think your wood isn't dry enough for heat yet. The years matter not, its all about what RH its been stored in and for how long.
Chris I think your on to something....
Richard,
The more I look at your pic's I have questions on how your doing your reflexing. Are you heating a section close to the riser bending it and then moving slowly towards the tips?
Worst thing I have done is got in a hurry and put too much pressure on the wood with the clamps before the temperature of the wood was right.
Just asking???
DBar
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Thanks everyone for the thoughts and insights here
Dbar, thanks...yeah that old persimmon bow you saw is still a great shooter at 60#. It about all the weight I can handle!
on this osage I was heating up and down that limb and just keeping my hand weight closer to the tip to feel it almost bend by itself so I don't think THAT was the problem.
But maybe it IS a problem?...maybe i should be bending a little at a time from the riser...just don't want to scorch the wood I guess
Pearl , yeah, it might be that it is a bit too thick still to deflex....and the dryness ..never even thought about that. I keep my staves in the rafters in an uninsulated shed
so normally everything seems ultra dry....but we did have a wet summer here in Oklahoma.
You're an expert on flipping tips, how thin do you shave the ends before steam bending em? mine are about 1/2" at the present.
I'm also glad you think its a strange crack, because I have a number of fair staves I got from the log of osage someone was selling for fence posts out here. $12 a log!
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At first look I thought it might be related to still having too much moisture, and the cells rupturing out from the side, though I don't think it was a major cause(though it still could factor in somewhere in the problem).
Definitely an unusual crack. I think there are a lot of factors involved. That clamp is right above a knot, which turns it into a real stress point, when you crank down on the next clamp in sequence. Kind of like using your knee as a fulcrum when breaking a branch for firewood.
Combine that with not enough time with heating to penetrate right into the centre of the stave.
Easy enough thing to do, especially if you haven't done many staves.
I found since using cooking oil to heat in a reflex or straighten I have had less problems. Somehow seems to help the heat penetrate deeper, or trap it in better.
Also wait for the wood to relax. If you tighten the clamp and still get resistance at that spot you need to heat it for longer.
Like the other guys have said super glue and clamp. Just make sure to pad the back with a thick piece of leather so you don't bruise the back with a clamp. Don't reheat the wood as the superglue will vaporize, and the crack will open up again.
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I have tried to make several bows that had side cracks, all failed. I believe side cracks indicate faulty, weak, wood, this has been my experience, others may have had some luck with the stuff but I haven't.
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Hamish ,yeah....I've been avoiding cooking oil only because once its soaked in it gums up sandpaper when finishing it
but I'm sure it would help get the heat distributed deeper. do you de-gum yours after oiling?
I'm thinking more and more its a moisture problem because it started as a very thick stave just a few says ago
and the crack seemed VERY difficult to clamp shut which makes me think it was actually tearing away in a shrinking action.
and Eric, the crack does seem to be opening along a slightly darker ring in the wood....which makes sense that any shrinking away would find the weakest ring
glued it and have decided to set it aside to cure for awhile, to dry, tackle it at a later date.
probably oughta whittle down a lot of my staves
well, for now I have a couple dogwood staves waiting to be experimented on.
appreciate everybodies thoughts...its likely a combination of being too thick, to much moisture and uneven heating with the gun.
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just wash the cooking oil off with hot water and soap
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That's what I do, Brad. I use Dawn dish soap and warm water to wash and rinse with boiling water. That's how I prep for sinew backing too.
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next one I'll definitely give that dish soap a try!
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This stave showed some checking on the side before i started a bow. The picture shows what happened when I applied sinew, the bow pulled apart as the sinew dried, weak wood for sure.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/crackedsinewbow.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/crackedsinewbow.jpg.html)
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I have to say I would not be able to trust that bow, even if I got it shooting. Happy to have you prove me wrong. :)
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now its kind of a challenge. >:D
I dripped super glue down the crack and scraped that edge till there's barely a detectable crack line at all showing.
for osage it needed thinning down anyway... been so used to making flatter wider fade bows,
but i've set it aside to cure for awhile and dry through...i'll let y'all know when(or if) i get her flinging arrows
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If that crack developed while using dry heat then it is a moisture issue. I have had that happen to me several times when shaping blanks that were too thick for making Warbows, primarily when using HHB. I believe what happens is that moisture inside the wood gets pushed ahead of the heat-gun making the wood swell to the point of it splitting on the sides. I've never had a bow fail from this. Unless you are making a Warbow then you should thin the wood before using dry heat. If you are making a Warbow then the only solution I have found is to do the heat-treating/shaping in short sections letting the wood rest for a day or more in between
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Thanks Marc
I'm thinkn that's exactly what it was...moisture deep inside the stave being heat-forced out , finding the weakest ring available to exit.
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if Marc has not had a failure,,,, then I would be encouraged to proceed and see if I could get the bow to shoot,,if you are worried then maybe make the bow a little lighter,,, but I definitely think it is worth a try,, :)
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I know I'm late here, but the only times I had cracks that looked like that were when I got too aggressive trying to take twists or lateral wobbles out of staves and left them too thick. So, torsion. I mentioned because I see a raised knot in the pic just left of the crack, and near the clamp.
I had this really cool BL stave like that once with side to side wobbles, like banked hairpin curves on a motorcycle track. Well one went right through the handle, so the faces of the limbs right off the fades were about 10-15 degrees off of parallel. I cranked them around a lot on a form and tried to cook them in place with the heatgun, but immediately a crack like that opened on the top fade on one side, and the bottom fade on the other. Ruined it.
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yeah, I've had mixed luck with Black Locust for that very reason
and some of the dark grain rings just seem to open up but my experience with BL is little.
...we'll see how this one holds up after i let it cure a while !