Not sure what happened...

[bowmad]

Had probably at least 100 arrows through the new bow. Took it out today to shoot a few, then on the third arrow... POW! The sound of the bow and my heart breaking.        I had been keeping an eye on the belly for fractures but there were none, and the back seemed like it was holding up well.  Anyway, here are some pictures for critiquing.  My bow making career is dangerously close to bankruptcy if I can't get a decent bow! So HELP!

This is from the belly side.
   
 
The other limb.
 

[Echatham]

Need lots more info.  Type of wood.  Dimensions.  Full draw or tillering pics would help.

[Dan Landis]

Did both limbs break at the same time?  

Looks like a crack on the bottom pic below the break.

[Wolftrail]

What the others say.   But just guessing I would say maybe very dry wood or tillering issues. I had an oak bow break the same way, wood was on the brittle side.
Don't give up I broke a few before I had a keeper. Using mostly maple now, very forgiving. And all the stuff I get is very consistent for dryness.

[Pat B]

Will you post pics of the back. I think explosive breaks like this are tension failures or bad grain with too steep of runoffs.

[monterey]

The belly pic looks like grain runoff.

[Bowjunkie]

Too dry is a distinct possibility.

[takefive]

Sorry to hear it.  What kind of wood was it?

[LittleBen]

Sorry to see that.

I assume this is the maple backed walnut you posted recently.

I think the evidence shows, and the consensis is that this is a TENSION failure.

Splinter lifted on the back at the edge of the limb and propogated through the whole limb.

Why? could be too dry, could be excessive grain runout, could be the edges of th elimb were not rounded over enough. Sometimes if you get fretting, and slight hinging it can fail in tension at that spot. Probably a combination of those factors.

Sometimes theres just a flaw in the wood you can't see and the bow is doomed and you just don't know it.


If you want to go with the most bulletproof approach, I'd recommend doing a hickory or bamboo backed bow, mayeb ipe, or osage belly.
Or just asimple hickory board can be very durable, and not likely to have a tension failure if the grain is straight. I know some have had success with maple backing, but I can say from experience that I've never had a hickory backing fail when the grain was straight.

[bubby]

cant see the backer but the belly needed the edges rounded a lot more than shows, round all edges good, I pretty bullet proof design, and nothing is bullet proof, is 68"ttt pyramid layout, I would use hard maple, 1 3/4" wide at the fades straight taper to 1/2" tips, 4" grip with 2" long fades, even limb thickness to start of 1/2" be picky about grain, and round all edges well, I have built maybe 30 bows with this layout and material with one failure so I know you can do it, white oak will work to and it breaks after hickory in bend tests

[bowmad]

Thanks for the input guys. On further investigation it does appear that a) there was a tension failure in the maple on the upper limb, b) the walnut was too dry. I think the tension failure could have originated from a small nick torn out by the planer that I didn't catch. The bow was 68" ttt, 1&3\\4" to mid limb tapering to half inch nocks.
I have enough wood to do a 65" bow the same width. I also have a 65" red oak board I could use.
So question 1. Is there anything I can do for the walnut to help the dryness problem e.i. Sticking it in the shower?
2. Should I try the maple backing again just paying extra attention to the back?
3. Should I set the walnut and maple aside and go back to the red oak? (I hope not)
4. Would a tri lam of all three woods be something to consider?

unfortunately I don't have any tiller or full draw pics for y'all to look at to further dissect. It's a little late at this point

[bowmad]

Haha. I will try to post a picture of the back this evening though.

[bubby]

what is your draw length, 65 is a little short with you trying to get your first shooter unless you go with a bendy handle bow, the only problem with maple is sometimes you get a little figure in the wood then I wont use it for a backer, for a bendy go 1 1/4" wide and parallel for the middle 16" then straight taper to 1/2" tips find center and go 2" both sides for the grip, 1 1/2" from there for fades and start your taper from there to the tips

[bowmad]

Here's the back.
I've made a few shootable bows so far that ended up given away to friends for Christmas and one that was underweight, but this was my first attempt at backing with wood. It was nearly impossible to find a "perfect" piece of maple. I'm not sure it can even be found from what I've seen! Anyway, I'll look into the bendy handle design for sure.

[bowmad]

Bubby, my draw length is 28"

[LittleBen]

I haven't used walnut as a belly, but I know that walnut is not very dense wood. Maybe .55SG, and hard maple also is not that dense.

I beliueve that red oak is quite a bit more dense than either of those two, and so for a given length and width, should be a better choice. than a maple-walnut combo.

For 28" draw and 50# with a 65" red oak board, I'd probably go like 2.5" wide at the fades, 2" at midlimb, and .5" tips. Or maybe 2" wide for 2/3 or the limb then taper to .5" tips.

Thats probably wider than absolutely necessary, but better to go a little wide than a little narrow IMO.

The real answer is probably to use whatever has the straightest grian.

[bubby]

at 28" that bendy will work fine, and I think once you shoot one you will like it