Osage Blow Up

[bentstick54]

Well my luck finally ran out. I posted earlier this month on my 15th bow under “ tillering a reflexed stave”. It had 1 limb with some knots that I was worried about, and 1 clean limb. I tillered it out to 50# @ 28”. I put the knotty limb to the top thinking less stain. Tiller was not perfect but I thought pretty close. After about 200+ arrows the bottom limb, ( the clean limb) exploded. No warning tic, snap crackle, pop, nothing. Just as I hit full draw, BANG, it exploded.

I’ve had several that had splinters lift that I superglued down and wrapped, that have 1000 arrows through since. But this is the 1st total blowup I had.

This bow came from some old well weathered Osage that I had to go deep to get to good wood, and had multiple side checks that I finally got past any visible signs of just as I reached final width.

Would like opinions on whether it might have been bad tillering, possibly bad stave to start with, or some other defect that more experienced eyes might see.

[bentstick54]

More pics

[Digital Caveman]

Hate it when that happens, I had a very nice Maple/Purpleheart blow like that this spring   It had a highly strained back and a grain curl in one limb. 

Was there a nicked ring on your bow? What is the grain like at the extreme ends of the break? I think that would be where the fracture started.  How moist was the wood? I feel that dry wood shatters more.

A high definition closeup of the back side of the fracture would help, thanks.

[bradsmith2010]

lately bows have been blowing cause keeping them inside in very dry climate,, with wood stove etc, any chance you moisture content got to low on this one,,

[bentstick54]

I have stored all my staves in my basement as soon as I get them. I work on them in the basement also. No wood heat, gas heat with thermostat set at a constant 70dg. Basement runs 6dg to 8dg less year around in the basement, and I have no moisture meter. I did do some minor heat corrections, and let set for a week after to rehydrate before working on. Everytime I removed wood I exercised 30 times before scraping again. All shooting up to this point has been in the basement under same conditions.

[bentstick54]

Here is what I started with.

[bentstick54]

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[bradsmith2010]

  I think it is hard for a bow to re hydrate,, in low humidity,, but I am just guessing and that might not be what happened,, dont ask me how I know about this,, but I will say when mine blew up,, it was inside in the heat,, and I stuck the moisture meter in the blown up part and it was below 6%,, I had been shooting it all summer,just fine,, this was cold winter ,, when it blew,, so I am just paranoid,, and have noticed some bows blowing lately,, after heat treating etc,, I think spritzing with water after a heat treat might help,, but I am just guessing,,also  bow slightly overbuilt would be less likely to blow in questionable conditions,, that being said,, it might not be the cause of your blow up,, but something to consider in the future,, you didnt say how long the bow was,,

[bentstick54]

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[bradsmith2010]

how long was bow

[bentstick54]

Full draw

[bentstick54]

Brad, 66” ntn, 50# @ 28”, 1-1/2” at fades straight taper to 1/2” at nocks. 4” stiff handle with 3” fades.

[bentstick54]

Pics of work up on tillering on original thread last posted on Jan 7th.

[bentstick54]

Now that I think about it, the clean lower limb that blew was the limb that had the most natural reflex in it. I used dry heat on the end only for a little better tip alignment. I made a caul matching the reflex of that limb to use on the upper knotty limb to even the two out.

[RyanY]

Given that it lost all that reflex and the design, I think it was probably close to its limit. That lower limb should have been working more in the inner limb for that pyramid profile. It broke where it was bending the most. Even getting a bit too dry or a small imperfection could have pushed it over the edge.