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Author Topic: Diagnostic issue w/ pics  (Read 5367 times)

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Offline upstatenybowyer

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Diagnostic issue w/ pics
« on: July 23, 2018, 07:13:08 am »
I changed the title.

So here's the problem:

I keep braking these highly reflexed wood-backed bows.  >:( I get them braced with a pretty even bend, then begin removing wood equally on both limbs to bring them to the target draw length. Somewhere between brace and full draw they just explode.  :o

What am I doing wrong? Grain runoff? The breaks appear to be happening mid-limb on the back where most of the reflex is. Am I trying to glue in too much reflex and therefore over stressing the wood?

The first 5 pics are of a maple-backed BL. The last 3 are from a maple-backed lilac.

I need to figure out why this is happening!

« Last Edit: July 23, 2018, 07:48:22 am by upstatenybowyer »
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

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Offline Ryan Jacob

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Re: Grain runoff on wood backing
« Reply #1 on: July 23, 2018, 07:30:35 am »
From what I heard, very. How bad is it?
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Offline PEARL DRUMS

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Re: Grain runoff on wood backing
« Reply #2 on: July 23, 2018, 07:33:05 am »
Run off is inevitable as the width profile tapers. Its the sharp run offs that will peel up or blow. Take a picture.
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Offline upstatenybowyer

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Re: Diagnostic issue w/ pics
« Reply #3 on: July 23, 2018, 07:49:18 am »
last ones
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline PEARL DRUMS

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Re: Diagnostic issue w/ pics
« Reply #4 on: July 23, 2018, 07:51:50 am »
Notice the breaks are nearly in the same areas? That's clue #1 your tiller isn't matching your design.
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Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline upstatenybowyer

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Re: Diagnostic issue w/ pics
« Reply #5 on: July 23, 2018, 07:57:06 am »
Could you elaborate a bit Pearly? Do you mean that the wood isn't working enough or too much in the wrong places?
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline PEARL DRUMS

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Re: Diagnostic issue w/ pics
« Reply #6 on: July 23, 2018, 07:57:53 am »
Its working too much where it broke. If you had grain or run off issues the areas that break would be all over, nit in the same place every time.
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Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline upstatenybowyer

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Re: Diagnostic issue w/ pics
« Reply #7 on: July 23, 2018, 08:03:24 am »
That makes sense. The problem is the thickness is even through out the limbs w/ the width tapering. Do you think the limbs are too narrow or not thick enough?
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline PEARL DRUMS

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Re: Diagnostic issue w/ pics
« Reply #8 on: July 23, 2018, 08:15:57 am »
Hard to say without seeing it pre-break. The 3rd to last pic. Your reflex start just off the fade and stays straight after that. That whole limb needs to bend, if you tillered that to predetermined shape you had in mind and not to what that limb needs, it will break, like it did, every time.
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Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline bushboy

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Re: Diagnostic issue w/ pics
« Reply #9 on: July 23, 2018, 08:16:25 am »
What type of glue?
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Offline upstatenybowyer

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Re: Diagnostic issue w/ pics
« Reply #10 on: July 23, 2018, 08:28:24 am »
Smooth on bushy.

I think I understand what your saying pearl. Thanks a bunch for your thoughts.
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline PEARL DRUMS

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Re: Diagnostic issue w/ pics
« Reply #11 on: July 23, 2018, 08:32:12 am »
I could explain it easily in two sentences if I was looking at you and the bow.
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Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline Pat B

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Re: Diagnostic issue w/ pics
« Reply #12 on: July 23, 2018, 08:33:26 am »
They look like tension breaks to me. Where are you getting the maple backing from? are you cutting it yourself? Was it cared for properly from the stump?
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Offline upstatenybowyer

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Re: Diagnostic issue w/ pics
« Reply #13 on: July 23, 2018, 08:38:21 am »
Quote from: Pat B on July 23, 2018, 08:33:26 am
They look like tension breaks to me. Where are you getting the maple backing from? are you cutting it yourself? Was it cared for properly from the stump?

I know what you mean Pat. I've been questioning the quality of the backing. It's quarter-sawn maple I got from a local lumber store. I cut them from a board I bought there. I'm sure it's kiln-dried. No way to know how it was cared for I guess.
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline bushboy

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Re: Diagnostic issue w/ pics
« Reply #14 on: July 23, 2018, 08:39:45 am »
My best guess is a combo of what was stated and to much pressure at glue causing a staved joint.oh my I have broken so many backed bows!
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Some like motorboats,I like kayaks,some like guns,I like bows,but not the wheelie type.
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