Board Bow Help

[allpowerfulguru]

Well first off, hello to all! I have been lurking for a while but finally got around to joining. I love this forum and have already learned a lot from everyone's conversations. I am new to bow building, but have done a lot of research and am currently following a red oak board bow build along for my first bow.
I have the bow tillered to a low brace and it is pulling about 25# at 20 inches. The limbs are bending nice and even with no perceptible hinges or flat spots. The problem is that when I pull it past about 18 inches it starts crackling and I can hear fibers breaking. I have been exercising the limbs before each trip to the tillering tree, but it still feels like it is going to blow anywhere past 18 in.
The bow is designed to pull 45-50# at 28 inches and I don't know why there seems to be so much stress in the limbs when they are not pulling near the final draw weight and I am getting close to the final draw length.
Any insight or wisdom would be greatly appreciated. Thanks for any help.

[PEARL DRUMS]

Pics, pics pics. Crackling sounds are never good.

[Roy from Pa]

Start another bow..

[allpowerfulguru]

Any idea what the problem could be? If I have ruined the bow, then I have no idea what I did wrong. I never strained it over its draw weight, exercised the limbs, there is currently less than an inch of set in each limb, and although I am an amateur tillerer I really don't see any major flaws in the limbs. It is red oak board, 70in ntn, a 2in back, and backed with fiberglass tape. There are no visible cracks or frets that I can detect.

I know that its not a big deal in the scheme of things since I will be building another bow but I was really trying to not screw this one up, not to mention that it has taken me months to get to this point. Here is the link to some pics.
    http://s1199.photobucket.com/albums/aa475/allpowerfulguru/
Thanks for any help.

[fujimo]

how did you attach the fiberglass tape?

[allpowerfulguru]

titebond 2, then tape and let dry. repeat 3 times

[4est trekker]

If I had to guess, I'd say it's the multiple layers of tape causing the cracking sounds.  You should only apply one layer of most any backing, save for sinew.  Not the best news, but I hope that helps.

[allpowerfulguru]

That makes sense, guess I will just carry on and see what happens. Thanks

[allpowerfulguru]

And this is what happened. I was hoping it was just the backing, but I had an ominous feeling. I got to 30# at 22in and the right limb collapsed. Still don't know what happened. Could anybody see a problem with the tiller, or could it have been a flaw in the wood? Critiques welcome. Thanks

 

[vanillabear?]

[PEARL DRUMS]

You over powered your oak core with a ton of fiberglass on the back. On that note, I have no use for oak boards. Just my opinion. I see more oak failures on multiple sites than I do any other board by a mile. Im sure its because more oak boards are used than any other. Doesnt matter to me; I still hate oak boards. Get some hickory boards and skip the backing. Just build a bow. Menards carries a great selection of hickory if you have one near by.

[wildbill001]

I'd vote for internal flaw and/or pin-knot.  Sort of the same thing happened on my son's first bow.  It was not backed however.  

On his, the pin-knot showed up when he was cutting/shaping the handle and arrow-shelf.  At that point we figured, "what could go wrong".  Well after about 20 arrows through, CRAAACK.

Oh well, only thing lost was about an $8 board and about 8 hours work.

Bill

[allpowerfulguru]

I was kinda hoping it was the board ( a little easier on the ego). Anyway, I might be done with board bows for a while. Think I am going to attempt a selfbow. That is what really fascinates me about bow making anyway. Starting with a tree and crafting it into a functional bow.
Well thanks for all the input from everyone. I am sure I will be asking more questions in the near future. See ya'll around.

[George Tsoukalas]

That stave looks awfully thick to be bending much.  There are buidalongs on my site . There is a buidalong for a red oak board that bends in the handle. There is info on silk and burlap backings too. Nothing on FG backings. Jawge