Just Busted Another One!!%#%$##

[Easternarcher]

P.S. just did a sacrificial bend test on a strip that I'm 99% positive came from the same batch(2" board re-sawn).
the full length strip bent almost completely double before failing into popped splinters. I had to force it to fold over to separate the two pieces.
So.....I need to examine and test every piece I have to be somewhat sure it is sound I guess. Might even do a hick backed ipe or bloodwood etc. to test it again. I'm still confused by it all.LOL.

[mikekeswick]

Well thats a clean tension break.
The hickory was the problem.
It's impossible that the osage was at fault. If the osage had some sort of fault it would either have chrysalled or taken set here.
Doing bend tests on thin backing strips is pretty much a waste of time. You need to glue some scrap belly wood onto it so that it's at the same sort of thickness as a limb (back and belly) then bend to the same degree as a bow limb.

[Easternarcher]

Well thats a clean tension break.
The hickory was the problem.
It's impossible that the osage was at fault. If the osage had some sort of fault it would either have chrysalled or taken set here.
Doing bend tests on thin backing strips is pretty much a waste of time. You need to glue some scrap belly wood onto it so that it's at the same sort of thickness as a limb (back and belly) then bend to the same degree as a bow limb.

OK, thats the next move then.
Set or chrysalis????it never had the chance to get that far. LOL.

[adb]

That hickory looks like heartwood, not sapwood. You want the sapwood for backing strips. It should be very white if it's sapwood. I had the same problem with hickory when I tried to use heartwood.

[Easternarcher]

That hickory looks like heartwood, not sapwood. You want the sapwood for backing strips. It should be very white if it's sapwood. I had the same problem with hickory when I tried to use heartwood.

ADB, this was quite white in colour, mqaybe alittle creamy looking.. the pic may be off...
The bend test strip I used last night in contrast was darker and it bent like crazy! and splintered alot when it failed. I dunno what to do here.

[Pappy]

Looks like the Hickory to me,I do the bend test also and I have found it very useful, I just use a short sliver, maybe 5 or 6 inches long and thin it down even so it will bend pretty even,not a long piece and if the Hickory has dry rot it will break across the back just like that one did.  if it break I scrap the wood that it came from.
   Pappy

[JackCrafty]

Breaks on the tension side of the wood break cleanly.  The splintering occurs in the neutral plane area.

That limb was overstressed.  Try making the limbs wider.

[Easternarcher]

Breaks on the tension side of the wood break cleanly.  The splintering occurs in the neutral plane area.

That limb was overstressed.  Try making the limbs wider.

Limbs were 1 7/16" or so already.

[JackCrafty]

Too narrow.  And not because they are 1-7/16 in wide.  They are too narrow because the limb broke.  If the limb breaks when the limb is 2" wide, then the limb is STILL too narrow.  Eventually you will find the width that will work.

[DarkSoul]

They are too narrow because the limb broke. 

I have to disagree with you. There are dozens of reasons why a bow can break. The limbs being too narrow is just one of them. Concluding that a wrong design (limb width) was used, just because the bow broke, is simply wrong.

I've never worked with osage, so I can't say for sure if a width of 1  7/16" was too narrow for the desired draw weight Easternarcher was after. It depends on the length of the bow, the draw weight and the draw length. But I think that width can't be that far off. Judging from the pictures, I'm pretty confident the hickory is the culprit - not the limb width. Yeah, maybe this particular piece of hickory was so lousy that a limb width of 4" may have been enough to give you a bow, but that would have been stupid. Hickory should not break like that, not even if the bow were underbuilt. If it does break like that, there's something wrong with the hickory itself. Don't use any more wood from this particular board. I'm not sure you should blame it on the hickory supplier; it could just be one faulty board in the batch.

[Easternarcher]

I have to disagree with you. There are dozens of reasons why a bow can break. The limbs being too narrow is just one of them. Concluding that a wrong design (limb width) was used, just because the bow broke, is simply wrong.

I've never worked with osage, so I can't say for sure if a width of 1  7/16" was too narrow for the desired draw weight Easternarcher was after. It depends on the length of the bow, the draw weight and the draw length. But I think that width can't be that far off. Judging from the pictures, I'm pretty confident the hickory is the culprit - not the limb width. Yeah, maybe this particular piece of hickory was so lousy that a limb width of 4" may have been enough to give you a bow, but that would have been stupid. Hickory should not break like that, not even if the bow were underbuilt. If it does break like that, there's something wrong with the hickory itself. Don't use any more wood from this particular board. I'm not sure you should blame it on the hickory supplier; it could just be one faulty board in the batch.
[/quote]

I agree wholeheartedly.
This hickory board came from the only local supplier that carries it. Can't blame them....the osage came from a bowyer supply place.
As for the design, I actually build most of my osage bows to around 1 3/8" width and 62-66" length...this one was at 68" overall. the osage was overly thick, maybe 9/16", the hickory was 3/16" thick. I planned on having lots of room to play with tiller etc. I was only shooting for a 40-45lb bow in the end. When it blew at only about 4" flex on the tree.
Did I overstress the limbs in exercizing them in floor tiller?....man if I did, it was doomed to fail anyhow in my opinion.

[JackCrafty]

If the limbs need to be 4" wide when using this batch of wood, then you know for sure that the wood is brittle.  But brittle wood is not the problem.  The problem is that the design you are using does not match the material.  If you want to keep trying until the material you obtain works well with your design, then expect to keep breaking bows.  It's not a bad approach, just and expensive one.

I'll be interested in seeing the final verdict.   

[adb]

Rubbish. Sorry... I have to disagree too. 1 7/16" wide hickory backed osage will give you whatever weight you want in a flatbow. That is PLENTY wide for this wood combo. I've made 100# hickory backed osage warbows, and 80# flatbows which were narrower. But yes, the tiller needs to match the design.

It's either the wood, or the tiller job. I seriously doubt this is purely a design flaw.

[JackCrafty]

It's either the wood, or the tiller job.

Which one do you think it is?  What method would you use to find out?

[adb]

No idea without seeing the bow or the tiller. If I had to guess... I'd say it's faulty wood. Making the limbs wider would not change the result IMHO.